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Pulsar

A pulsar is a rotating neutron star that emits beams of electromagnetic radiation from its magnetic poles, producing observable pulses as the beam sweeps across the line of sight to Earth, akin to a lighthouse effect.^[1] These compact objects, remnants of massive stars that have undergone supernova explosions, typically possess rotation periods ranging from milliseconds to seconds and magnetic fields up to trillions of times stronger than Earth's.^[2] Pulsars were first discovered in 1967 by graduate student Jocelyn Bell Burnell, who identified anomalous periodic radio signals in data from a telescope array constructed under the supervision of Antony Hewish at the University of Cambridge.^[3] The regularity and precision of pulsar signals have enabled applications such as high-precision timing for tests of general relativity, detection of gravitational waves via pulsar timing arrays, and the identification of the first confirmed exoplanets orbiting the millisecond pulsar PSR B1257+12.^[1] Key variants include rotation-powered pulsars driven by spin-down energy loss, millisecond pulsars accelerated by accretion from companion stars in binary systems, and magnetars characterized by ultra-strong magnetic fields exceeding 10^14 gauss that power sporadic bursts of X-rays and gamma rays.^[2]^[1]

Definition and Fundamental Properties

Core Characteristics

Pulsars are rapidly rotating, highly magnetized neutron stars that produce beams of electromagnetic radiation, predominantly in radio wavelengths, from polar regions accelerated by their intense magnetic fields.^[2] These beams, due to misalignment between the magnetic and rotation axes, sweep across the observer's line of sight during each rotation, resulting in periodic pulses observable as the lighthouse effect.^[2] The coherent nature of the radio emission stems from plasma processes in the magnetosphere, where charged particles generate curvature radiation and subsequent cascades.^[2] Observed rotation periods for pulsars span from 1.4 milliseconds to 8.5 seconds, with the fastest corresponding to spin rates exceeding 700 revolutions per second.^[2] All known pulsars exhibit spin-down, characterized by positive period derivatives indicating gradual slowing, primarily attributed to torque from magnetic dipole radiation that dissipates rotational energy into electromagnetic waves and particle winds.^[2] This energy loss rate, quantified as spin-down luminosity, scales with the magnetic field strength and rotation period, providing a key observable for inferring intrinsic properties.^[2] Pulsars are empirically distinguished from non-pulsing neutron stars by the detectability of their beamed, periodic emission, which requires favorable geometric alignment and sufficient emissivity. Inferred canonical properties include masses of approximately 1.4 solar masses, radii around 10 kilometers, and surface magnetic fields of about 10^{12} Gauss for typical young radio pulsars, derived from pulse timing, binary orbital dynamics, and spin-down measurements constrained by nuclear equation-of-state models.^[4]^[2] These values reflect the extreme compactness and density exceeding nuclear matter, with surface gravities roughly 10^{11} times Earth's.^[4]

Physical Model and Parameters

Pulsars are modeled as rapidly rotating neutron stars characterized by masses typically around 1.4 solar masses and radii of approximately 10-14 km, consistent with the Tolman-Oppenheimer-Volkoff equation under general relativity using a stiff equation of state (EOS) for dense matter.^[5] The internal structure features a thin crust of degenerate nuclei embedded in electrons and a core dominated by superfluid neutrons and possibly hyperons or quarks, with the EOS determining the pressure-density relation that supports the star against gravitational collapse.^[6] Observations from the Neutron Star Interior Composition Explorer (NICER) have constrained the EOS, yielding for the millisecond pulsar PSR J0030+0451 a mass of 1.34 +0.15 -0.16 M_⊙ and radius of 12.71 +1.14 -1.08 km at 68% confidence, or alternatively 1.44 +0.15 -0.14 M_⊙ and 13.02 +1.24 -1.06 km, favoring models without strong softening at high densities.^[7] ^[8] Magnetic fields, inferred from spin-down rates via the dipole braking formula B ≈ 3.2 × 10^{19} √(P \dot{P}) gauss, range from 10^8 to 10^{12} G for rotation-powered pulsars, with evolution driven by ohmic decay and possibly ambipolar diffusion in the core.^[2] Glitches, sudden increases in rotation frequency by Δν/ν ≈ 10^{-6} to 10^{-3}, provide empirical evidence for internal superfluid dynamics, where angular momentum transfer from pinned vortex lines in the neutron superfluid to the crust triggers the events, as supported by two-stream instability models in the core.^[9] The energy budget is dominated by rotational kinetic energy loss, \dot{E}_{rot} = 4π² I \dot{P} / P^3 where I ≈ 10^{45} g cm² is the moment of inertia, matching multi-wavelength luminosities from 10^{30} to 10^{36} erg s^{-1} across the population, with the spin-down powering magnetic dipole radiation, particle winds, and non-thermal emission while radio beaming represents a small fraction.^[2] This model aligns observed spin-down torques with empirical luminosities, though exact partitioning remains model-dependent.

Historical Discovery and Early Observations

Initial Detection

In November 1967, graduate student Jocelyn Bell, working at the Mullard Radio Astronomy Observatory near Cambridge, England, analyzed data from the Interplanetary Scintillation Array, a large radio telescope designed to study twinkling of distant radio sources caused by plasma in the solar wind.^[11] On November 28, she identified an anomalous signal consisting of regular pulses repeating every 1.337 seconds with a pulse width of approximately 0.04 seconds, originating from the direction of the constellation Vulpecula and designated CP 1919.^[3] Initially, the team, advised by Antony Hewish, considered artificial origins, humorously labeling it "LGM-1" for Little Green Men, but systematic checks ruled out terrestrial interference such as satellites or equipment artifacts.^[3] Hewish confirmed the extraterrestrial nature of the source through observations of its interplanetary scintillation pattern, which matched that of distant astronomical objects rather than nearby man-made signals, as the scintillation decorrelated over baselines consistent with a remote origin.^[12] Further analysis revealed a gradual slowing of the pulse period, or spin-down, at a rate of about 10^{-12} seconds per second, providing evidence against steady-state models like rotating white dwarfs and favoring a cooling, magnetized compact object. The discovery was announced in a paper published in Nature on February 24, 1968, titled "Observation of a Rapidly Pulsating Radio Source," co-authored by Hewish, Bell, and colleagues, initially speculating on a possible connection to quasi-stellar objects but noting the pulsation's regularity as unprecedented. Subsequent theoretical interpretation shifted toward a rotating neutron star model when the observed properties aligned with predictions for such objects' magnetic dipole radiation and thermal evolution, though this identification solidified in the months following publication.^[3]

Key Observational Milestones

In late 1968, radio observations identified the Crab pulsar (PSR B0531+21) at the center of the Crab Nebula, the remnant of a supernova recorded in 1054 AD, providing direct evidence that pulsars are young neutron stars formed in core-collapse supernovae with characteristic ages of approximately 970 years.^[13] Concurrently, the Vela pulsar (PSR B0833-45) was linked to the Vela Supernova Remnant, associated with a historical supernova around 1066 AD, further validating the youth and supernova origins of these objects through positional coincidence and age estimates derived from spin-down rates.^[14] Optical pulsations from the Crab pulsar were detected on January 15, 1969, using a 36-inch telescope at Kitt Peak, confirming the emission mechanism extends beyond radio wavelengths and aligning with the neutron star model's predictions for beamed radiation from a rotating magnetosphere.^[15] In the early 1970s, the Uhuru satellite revealed X-ray pulsations from sources like Centaurus X-3, establishing pulsars as X-ray emitters powered by accretion or rotation, with the first such detection in 1971 expanding the observed spectral range. The discovery of the binary pulsar PSR B1913+16 on July 2, 1974, by observations at Arecibo demonstrated orbital dynamics in pulsar systems, enabling precise tests of general relativity through measurable periastron advance and orbital decay.^[16] The first millisecond pulsar, PSR B1937+21, was identified in 1982 via Arecibo observations, revealing short spin periods (1.557 ms) indicative of spin-up via accretion in binary systems, contrasting with the longer periods of isolated young pulsars.^[17] Large-scale surveys in the 1990s and 2000s, including Parkes multibeam efforts and Arecibo's PALFA, cataloged hundreds of millisecond and normal pulsars, growing the known population to over 3,000 radio-detected objects by the mid-2010s through systematic blind searches sensitive to low-dispersion measures.^[18] The Fermi Gamma-ray Space Telescope, operational since 2008, identified nearly 300 gamma-ray pulsars by 2023, many without radio counterparts, highlighting high-energy emission from magnetospheric processes and blind searches via timing analysis of unidentified sources.^[19] By 2025, the total exceeded 3,700 known pulsars, reflecting cumulative empirical progress in instrumentation and survey techniques.^[20]

Nobel Prize Controversy

In 1974, the Nobel Prize in Physics was awarded jointly to Martin Ryle and Antony Hewish "for their pioneering research in radio astrophysics: Ryle for his observations and inventions, in particular of the aperture synthesis technique, and Hewish for his decisive role in the discovery of pulsars."^[21] Ryle's contributions centered on developing radio interferometry methods that enabled high-resolution imaging of celestial radio sources, while Hewish was recognized for designing the 4.2-acre interplanetary scintillation array at the Mullard Radio Astronomy Observatory, which serendipitously detected the periodic signals later identified as pulsars.^[21] The Nobel Committee's rationale emphasized the supervisors' roles in establishing the experimental frameworks, adhering to longstanding precedents favoring principal investigators over junior contributors in award allocations.^[22] Jocelyn Bell Burnell, Hewish's graduate student, played the central operational role in the discovery by meticulously analyzing the array's chart recordings, which produced over 120 miles of data per four-day cycle.^[23] On November 28, 1967, she identified the first anomalous "scruff" of regular pulses with a period of 1.337 seconds, initially labeled LGM-1 (Little Green Man 1) to denote its artificial-like regularity, before confirming it as a natural astrophysical phenomenon.^[11] Bell Burnell processed and sifted the raw data, spotting the signal amid noise from the scintillation experiment intended to study twinkling radio sources from distant quasars, a task Hewish later described as pivotal to recognizing the discovery's significance.^[24] She co-authored the seminal 1968 paper announcing pulsars in Nature, yet was excluded from the Nobel as a student, consistent with the prize's historical bias toward senior figures who conceptualize projects rather than execute data reduction.^[25] The omission sparked immediate and enduring debate within the scientific community, with critics arguing it undervalued empirical groundwork—Bell Burnell's anomaly detection—over instrumental design, potentially overlooking causal contributions from data handling in serendipitous findings.^[26] Protests included letters from astronomers in the 1970s questioning hierarchical credit norms, and ongoing discussions have highlighted gender dynamics, as Bell Burnell herself reflected that a male student might have received different consideration, though she expressed no personal resentment, noting the prize's life-disrupting demands and her subsequent career successes.^[27]^[28] The controversy underscored tensions between institutional conventions and verifiable individual impacts but did not alter pulsar research trajectories, as subsequent observations validated the signals' neutron-star origins independently of attribution disputes.^[29]

Formation and Evolutionary Processes

Origins in Supernovae

Pulsars originate from the core collapse of massive stars with initial masses greater than 8 solar masses, which undergo Type II, Ib, or Ic supernovae.^[30] These progenitors evolve through hydrogen and helium burning stages, developing iron cores that become unstable and collapse under gravity when fusion ceases, rebounding to expel outer layers and form a compact neutron star remnant.^[31] The resulting neutron stars typically have masses around 1.4 solar masses, with radii of approximately 10-15 kilometers, stabilized by neutron degeneracy pressure.^[32] Asymmetric mass ejection during the supernova explosion imparts significant natal "kicks" to the newborn pulsar, with observed space velocities ranging from 100 to 500 km/s on average, and up to 1000 km/s in some cases, arising from hydrodynamic instabilities or neutrino asymmetries.^[33] ^[34] These high velocities disrupt most close binaries, leaving many pulsars isolated, consistent with the prevalence of single-star evolutionary paths to core collapse.^[35] The core-collapse mechanism dominates pulsar formation, as evidenced by the association of young pulsars with supernova remnants and the alignment of pulsar birth rates with observed core-collapse supernova frequencies, which exceed those of rarer alternatives like accretion-induced collapse by factors of hundreds to thousands.^[36] ^[36] Prominent examples include the Crab pulsar (PSR B0531+21), formed from the Type II supernova recorded in 1054 AD within the Crab Nebula remnant, where the pulsar's rotation axis aligns with the expanding shell's symmetry axis, indicating minimal initial misalignment from the explosion dynamics.^[32] Similarly, the Vela pulsar (PSR B0833-45) resides in the Vela supernova remnant, dated to approximately 11,000 years ago, with its pulsar wind nebula and shell expansion providing direct evidence of a recent core-collapse event powering the remnant's structure.^[37] These associations, along with statistical matches between young pulsar populations and core-collapse rates—dominated by Type IIP events at ratios of about 10:1 over Ib/c—underscore the empirical link, distinguishing this isolated formation channel from binary recycling processes.^[36]

Binary Recycling Mechanisms

In binary systems, neutron stars can undergo spin acceleration through the accretion of mass and angular momentum from a low-mass companion, a process known as recycling that transforms ordinary pulsars into rapidly rotating millisecond pulsars. This occurs primarily in low-mass X-ray binaries (LMXBs), where the neutron star accretes material via Roche-lobe overflow or wind capture, generating torques that reduce the spin period from typical values of hundreds of milliseconds to as short as 1-2 milliseconds over timescales of $10^8 to $10^9 years.^[38]^[39] The sustained accretion also weakens the neutron star's magnetic field from \sim 10^{12} G to \sim 10^8 G, reducing electromagnetic spin-down torques and allowing the rapid rotation to persist post-accretion.^[40]^[41] Observational evidence for recycling derives from the tight correlation between pulsar spin periods and binary orbital parameters, as predicted by accretion models and verified in population studies of LMXBs transitioning to radio pulsars.^[42] For example, the double pulsar PSR J0737-3039A/B features a recycled 22.7-ms pulsar (A) orbiting a 2.77-s pulsar (B) with a 2.4-hour period, where the spin and magnetic axis orthogonality of A (\sim 90^\circ misalignment) aligns with expectations from prolonged accretion torquing rather than isolated evolution.^[43] This system's orbital eccentricity (0.088) and periastron advance further constrain the recycling efficiency, matching simulations where accretion episodes dominate spin evolution without requiring fallback supernovae for B's formation.^[44] Population statistics, including the scarcity of young pulsars in short-period binaries, further support LMXBs as progenitors, with recycling explaining \sim 10\% of the galactic millisecond pulsar census.^[45] Spider pulsars, encompassing black widows (companions \lesssim 0.03 M_\odot) and redbacks (companions $0.1-0.5 M_\odot), represent active or transitional phases of post-recycling interaction, where pulsar winds ablate the companion, causing orbital decay and radio eclipses.^[46] In black widows, high-energy irradiation evaporates the low-mass companion, leading to \sim 1-10\% mass-loss rates and pulsed optical/X-ray modulation; redbacks exhibit similar dynamics but with less ablation due to larger companions.^[47] The 2025 SpiderCat catalog documents 111 such systems (50 black widows, 30 redbacks), with recent additions like PSR J1544-2555 (2.4-ms spin, 2.7-hour orbit) providing multiwavelength evidence of ongoing wind-companion interplay that halts full recycling quiescence.^[46]^[48] These eclipsing binaries, often Fermi-detected, validate recycling endpoints through measured orbital inclinations (>80^\circ) and companion heating, distinct from isolated spin-down.^[49]

Spin-Down and Endpoint Scenarios

Pulsars exhibit observable spin-down through a gradual increase in rotation period P, quantified by the period derivative \dot{P}, primarily attributed to energy loss via magnetic dipole radiation. The standard model posits that the torque arises from the rotating magnetosphere, yielding a spin-down rate approximated by \dot{P} \propto B^2 P^{-3}, where B is the surface magnetic field strength; this relation is derived from equating the radiated power to the rotational energy loss and empirically fitted to timing data across populations.^[2]^[50] Deviations manifest as timing noise, including stochastic wander and discrete glitches—sudden spin-ups that temporarily counteract deceleration, as seen in the Vela pulsar (PSR J0835-4510), which experiences glitches every 2–3 years with fractional frequency jumps \Delta \nu / \nu \approx 10^{-6} and associated energy releases on the order of $10^{18} erg from internal superfluid readjustments.^[51] These events challenge pure dipole braking by implying internal angular momentum reservoirs that episodically couple to the crust, altering \dot{P} post-glitch via recovery phases lasting days to years.^[52] In isolated pulsars, evolutionary tracks in the P-\dot{P} diagram trace characteristic ages \tau = P / (2 \dot{P}) from milliseconds to billions of years, with spin-down continuing until pair production in the polar cap ceases, marking a theoretical "death line" beyond which radio emission halts due to insufficient accelerating electric fields. No sharp boundary is confirmed observationally, as surveys reveal statistical cutoffs rather than a precise line, with sparse pulsars near or below predicted thresholds (e.g., PSR J0250+5854 at P = 23.5 s), attributable to viewing geometry, magnetic field decay, or model uncertainties in gap physics.^[53]^[54] High-\dot{P} evolution implies eventual quiescence as rotation-powered emission fades, leaving undetected neutron stars. Binary systems introduce additional endpoints, where spin-down competes with or transitions to accretion-driven phases; in propeller regimes, rapid rotation expels infalling material from the magnetosphere, suppressing luminosity and enforcing quiescence akin to isolated objects, as modeled for low-mass X-ray binaries fading below $10^{34} erg/s.^[55] Close orbits drive inspiral via gravitational wave emission, culminating in mergers; neutron star binaries like PSR B1913+16 are projected to coalesce within Hubble time, potentially forming black holes if combined masses exceed \sim 2.5 M_\odot, though direct endpoints remain unobserved pending advanced detectors.^[56] Such scenarios link spin-down halting to dynamical fates, with no evidence for prolonged emission post-merger.

Classification and Variants

Rotation-Powered Pulsars

Rotation-powered pulsars, also known as canonical or normal pulsars, derive their emission energy primarily from the loss of rotational kinetic energy through magnetic dipole radiation and particle wind mechanisms.^[57] ^[2] The spin-down luminosity \dot{E} = 4\pi^2 I \dot{P} P^{-3}, where I is the moment of inertia, P the rotation period, and \dot{P} its derivative, powers particle acceleration in the magnetosphere, leading to beamed emission across radio, optical, X-ray, and gamma-ray wavelengths.^[58] Typical parameters include rotation periods ranging from about 0.1 to 10 seconds and surface magnetic fields of approximately $10^{12} gauss, inferred from the spin-down relation B \approx 3.2 \times 10^{19} \sqrt{P \dot{P}} gauss assuming vacuum dipole braking.^[2] ^[59] Young rotation-powered pulsars, such as the Crab pulsar (PSR B0531+21), exhibit short initial periods and rapid spin-down, with the Crab having a period of 33 milliseconds, a characteristic age of around 1240 years, and a magnetic field of about $3.8 \times 10^{12} gauss.^[60] ^[61] In contrast, the older field population features longer periods and slower evolution, reflecting cumulative energy loss over thousands to millions of years.^[62] Approximately 3630 such pulsars are cataloged in the Australia Telescope National Facility Pulsar Catalogue as of 2025, predominantly detected in radio surveys.^[63] Detection of rotation-powered pulsars is biased by geometric beaming, with emission cones subtending only a few degrees, and interstellar dispersion, which smears pulses from distant sources and favors nearby or high-luminosity objects.^[2] This results in an observed population skewed toward younger, more energetic pulsars, while the intrinsic Galactic distribution likely includes many more fainter, older examples below current sensitivity thresholds.^[62]

Millisecond and Recycled Pulsars

Millisecond pulsars represent a class of recycled neutron stars characterized by rotation periods typically shorter than 10 milliseconds and magnetic field strengths below $10^{9} to $10^{10} G, resulting from prolonged mass transfer and spin-up in binary systems. ^[64] These objects, numbering approximately 500 in total catalogs as of recent surveys, exhibit evidence of prior accretion through their low surface magnetic fields and, in binary cases, remnant low-mass companions.^[65] Unlike standard rotation-powered pulsars formed directly from core-collapse supernovae, recycled variants undergo evolutionary spin-up via angular momentum transfer from a companion, often a low-mass star, which deposits material onto the neutron star's surface over billions of years.^[66] This process weakens the magnetic field through burial under accreted layers and accelerates rotation to millisecond scales, distinguishing them observationally by their stability and reduced spin-down rates.^[58] A significant fraction of known millisecond pulsars reside in dense environments like globular clusters, where dynamical interactions facilitate binary formation and recycling; for instance, the cluster 47 Tucanae hosts 42 such systems, the largest known population in a single cluster.^[67] These cluster MSPs often display tight orbits and eclipsing behavior due to companion ablation by the pulsar's relativistic wind, as seen in "spider" binaries where the companion's geometry—either "black widow" (very low-mass, ~0.01–0.03 M_\sun) or "redback" (higher-mass, ~0.1–0.4 M_\sun)—leads to orbital modulations in radio and X-ray emission.^[46] The 2025 SpiderCat catalog compiles over 100 Galactic-field spider pulsars, providing multi-wavelength data on their spin, orbital parameters, and companion evaporation, highlighting active accretion remnants despite the cessation of mass transfer in many cases.^[46] ^[47] Disrupted recycled pulsars form a subclass of isolated millisecond or mildly recycled objects (periods >20 ms but with B < 3×10^{10} G) arising from binary disruption, typically via the supernova explosion of a secondary star that imparts a natal kick, ejecting the pulsar into the field while preserving recycling signatures.^[68] Chandra X-ray observations of these systems reveal thermal emission consistent with heated polar caps and non-thermal magnetospheric activity, supporting their binary origins without current companions.^[69] Such disruptions explain the existence of field-isolated MSPs, bridging evolutionary models between standard and fully binary-recycled populations, with empirical evidence from their spin distributions and field strengths aligning with accretion-induced modifications rather than primordial values.^[70]

High-Magnetic-Field Variants

High-magnetic-field variants of neutron stars, collectively termed magnetars, are characterized by surface dipole magnetic fields exceeding $10^{14} gauss, inferred from their rapid spin-down rates via the relation B \propto \sqrt{P \dot{P}}, where P is the rotation period and \dot{P} its time derivative.^[71] These fields, up to $10^{15} G in some cases, dwarf those of typical rotation-powered pulsars by factors of 100 to 1000, powering their emission primarily through magnetic dissipation rather than rotational energy loss.^[72] Soft gamma repeaters (SGRs) represent one subclass, distinguished by recurrent bursts and occasional giant flares in the gamma-ray band. The most energetic such event occurred on December 27, 2004, from SGR 1806-20, releasing an isotropic energy of approximately $2 \times 10^{46} erg in a brief spike followed by a pulsating tail lasting about 500 seconds. This flare's intensity disrupted Earth's ionosphere and highlighted the role of magnetic reconnection in liberating stored magnetic energy.^[73] Anomalous X-ray pulsars (AXPs), the other main subclass, exhibit persistent pulsed X-ray emission with luminosities around $10^{34-36} erg/s, often accompanied by timing irregularities such as glitches—sudden spin-ups—and rare anti-glitches (spin-downs).^[74] Long-term monitoring of AXPs like 1E 1841-045 has revealed multiple glitches with fractional changes \Delta \nu / \nu \sim 10^{-6} to $10^{-4}, challenging standard superfluid vortex models due to their frequency and association with outburst recovery.^[75] Observational evidence supports unifying AXPs and SGRs under the magnetar paradigm, with spectral and timing behaviors attributed to crustal fractures and field reconfiguration rather than distinct origins.^[76] Debates persist on field generation—fossil remnants from progenitor stars versus amplified dynamos—but empirical constraints from flare energetics suggest initial fields near the quantum limit (\sim 10^{15} G) decay over $10^4 years, consistent with observed spin periods of 2-10 seconds.^[77] High-field radio pulsars occasionally exhibit magnetar-like traits, blurring boundaries but reinforcing magnetic dominance in emission for periods P \gtrsim 5 s.

Exotic or Transitional Forms

AR Scorpii represents a rare example of a white dwarf exhibiting pulsar-like behavior, distinct from neutron star pulsars due to its lower density and composition. In this binary system, a rapidly rotating magnetic white dwarf with a spin period of approximately 117 seconds interacts with its M-dwarf companion, producing synchrotron radiation through magnetic pumping of coronal loops, resulting in polarized pulses observable from radio to X-ray wavelengths.^[78]^[79] Unlike neutron star pulsars, the white dwarf's emissions arise from binary interactions rather than a solid stellar remnant's rotation, highlighting a hybrid mechanism that challenges strict categorization while underscoring the limitations of white dwarf matter in sustaining extreme pulsar densities. Transitional millisecond pulsars bridge accretion-powered and rotation-powered phases, switching between states where an active accretion disk quenches radio pulsations in favor of X-ray emission, and a propeller regime restores radio pulsar activity. Systems like PSR J1023+0038 demonstrate rapid mode switches, with brightness varying by factors of up to 10, attributed to matter ejections or variable accretion flows that alter the magnetosphere.^[80]^[81] These transitions, observed in a handful of sources since the mid-2010s, provide empirical tests of binary evolution models, revealing instabilities in low-mass X-ray binaries that recycle neutron stars without fully ejecting companions.^[82] Pulsar planets, such as PSR J2322−2650 b discovered in 2018 and further characterized in 2025, exemplify exotic survivability in post-supernova environments. This gas giant, with a minimum mass of 0.795 Jupiter masses and orbital period of 0.3 days around its millisecond pulsar host, features a carbon-rich atmosphere at ~1900 K, detected via JWST spectroscopy revealing strong C2 and C3 absorption lines indicative of disequilibrium chemistry and high-speed winds.^[83]^[84] Its persistence challenges models of planetary destruction during the progenitor supernova, suggesting formation from surviving debris or second-generation accretion, with the pulsar's low luminosity preserving the planet's integrity.^[85]

Detection Techniques and Nomenclature

Observational Methods

Pulsar signals are primarily detected in the radio band through searches for periodic pulsed emission, which requires correcting for dispersive delays caused by free electrons in the interstellar medium. The dispersion measure (DM), defined as the integrated column density of electrons along the line of sight, quantifies this effect, with observed delays scaling as \Delta t \propto \mathrm{DM} / \nu^2, where \nu is the observing frequency. Dedispersion pipelines apply trial DM values to align pulse phases across frequency channels, typically using incoherent methods for broad searches (summing intensity post-detection) or coherent techniques for higher sensitivity (phase-coherent summing). Subsequent periodicity searches employ fast Fourier transforms (FFT) for efficient power spectrum analysis or fast-folding algorithms (FFA) to handle non-stationary or long-period signals, enabling detection amid noise and radio frequency interference.^[86]^[87]^[88] Modern radio telescopes have accelerated discoveries through wide-field surveys and advanced processing. The Five-hundred-meter Aperture Spherical Telescope (FAST) has identified over 1,000 new pulsars since 2021, including 473 from its Galactic Plane Pulsar Snapshot survey, leveraging its high sensitivity for faint, distant sources. Similarly, the Australian Square Kilometre Array Pathfinder (ASKAP) detected two highly scattered pulsars in 2025 via circular polarization searches in continuum images, where pulse broadening timescales reached 290–343 ms due to interstellar scattering, followed by confirmation through dedicated timing. These pipelines often integrate GPU acceleration for handling large datasets, with dedispersion and folding optimized for real-time or archival analysis.^[89]^[90]^[91] In X-ray and gamma-ray bands, observations focus on timing the pulsed emission for precise pulse arrival times (TOAs), complementing radio data by probing magnetospheric processes less affected by dispersion. The Neutron Star Interior Composition Explorer (NICER) achieves sub-100 μs TOA precision through rotation-resolved spectroscopy, as demonstrated in multi-year monitoring of millisecond pulsars and glitch events. The Fermi Large Area Telescope has cataloged over 300 gamma-ray pulsars via phase folding of unbinned photon data against radio ephemerides or blind searches using maximum likelihood techniques, with detections extending to extragalactic sources. Polarimetric capabilities, such as those from the Imaging X-ray Polarimetry Explorer (IXPE), reveal phase-dependent polarization degrees up to 12% in pulsars like the Crab, highlighting emission asymmetries potentially linked to wind geometries, with analyses unifying soft X-ray and optical properties.^[92]^[93]^[19] Detection faces challenges from interstellar scattering, which broadens pulses via multipath propagation (strongest at low frequencies and near the Galactic plane), and nulling, where emission intermittently ceases, reducing detectability in standard folding. Mitigation involves higher-frequency observations or modeling scattering tails, though residual effects corrupt TOAs. Machine learning aids reprocessing of archival data, as in 2024 analyses uncovering faint pulsars in the Galactic plane via GPU-accelerated pipelines on old surveys, bypassing traditional thresholds for weak or scattered signals. Multi-wavelength pipelines integrate these modalities, folding high-energy photons with radio-defined phases for joint timing, while emerging multi-messenger approaches incorporate pulsar timing arrays for nanohertz gravitational wave correlations, though primarily enabling future cross-verification rather than routine detection.^[94]^[95]^[96]^[97]

Naming and Cataloging Conventions

Pulsars were initially designated with provisional names by their discoverers, such as CP 1919 for the first observed pulsar (Cambridge Pulsar at right ascension 19h 19m) or the informal LGM-1 (Little Green Men-1), reflecting early speculation about extraterrestrial origins.^[98] These ad hoc labels gave way to systematic conventions in the 1970s and 1980s to accommodate the growing number of discoveries and ensure unambiguous identification.^[99] The International Astronomical Union (IAU) established standardized nomenclature requiring pulsar names to follow the prefix "PSR" (Pulsating Source of Radio) with equatorial coordinates, explicitly indicating the equinox epoch to prevent confusion from precession.^[100] Early designations used the "B" suffix for B1950.0 coordinates (e.g., PSR B1919+21), common for pulsars discovered before the mid-1990s, while modern discoveries employ the "J" suffix for J2000.0 coordinates (e.g., PSR J1921+2153 for the same object), formatted as PSR JHHMM±DDMM with right ascension in hours and minutes, declination in degrees and minutes including sign.^[99]^[100] This IAU-preferred J2000 format supersedes discoverer-specific or temporary names, promoting consistency across catalogs and literature, with legacy B names retained for historical reference but mapped to J equivalents.^[99] The Australia Telescope National Facility (ATNF) Pulsar Catalogue serves as the primary repository, compiling ephemerides, timing parameters, and multi-wavelength data for over 3,000 known pulsars as of its August 2025 update.^[65]^[101] Maintained by the Commonwealth Scientific and Industrial Research Organisation (CSIRO), it integrates contributions from global surveys and is queried via tools like PSRCAT for standardized parameter access, including pulsar names with both B and J designations where applicable.^[65] Supplementary data from distributed computing projects, such as Einstein@Home, aid in validating and incorporating citizen-science-derived discoveries into the ATNF framework, enhancing completeness for faint or binary systems without altering core naming rules.^[102]^[103] These conventions facilitate precise referencing in research, decoupling identification from discovery context or instrumental details.^[100]

Emission Physics and Mechanisms

Primary Emission Theories

The leading theory for pulsar radio emission posits coherent curvature radiation from relativistic electrons and positrons accelerated along curved open magnetic field lines in the polar cap regions near the neutron star surface.^[104] In this model, primary particles gain Lorentz factors on the order of 10^6 to 10^7 via parallel electric fields, emitting curvature photons whose energy spectra enable pair production cascades in the strong magnetic field, generating dense bunches necessary for coherence.^[105] These pairs screen the accelerating fields and amplify emission through collective effects, with pair production thresholds determined by photon energies exceeding approximately 2 m_e c^2 in the strong-field regime.^[106] Empirical support includes the observed radius-to-frequency mapping, wherein emission altitudes increase for lower frequencies, aligning with ray propagation along diverging field lines from inner polar cap origins.^[107] This geometric effect, evident in profile broadening at decameter wavelengths for numerous pulsars, constrains emission heights to 1-10% of the light cylinder radius.^[108] Pulsar brightness temperatures reaching 10^{30} K or higher necessitate coherent mechanisms, as incoherent single-particle processes yield temperatures below 10^{12} K, incompatible with flux measurements.^[109] Alternative models invoking plasma instabilities, such as two-stream or Buneman instabilities for direct wave excitation, encounter empirical shortfalls: they struggle to sustain the required bunching densities and Lorentz factors without invoking pair multiplication akin to curvature-driven cascades, and propagation losses attenuate intensities below observed levels.^[109] First-principles analysis of acceleration and radiation in dipolar fields favors curvature emission, as synchrotron alternatives demand unrealistically high pitch angles for comparable power.^[110]

Multi-Wavelength Phenomena

Pulsars display pulsed emission spanning the electromagnetic spectrum, from radio frequencies through optical, X-ray, and into gamma rays, with beam geometries and spectral properties evolving with wavelength. Radio emission typically arises from coherent processes in open field line regions, manifesting as core beams from polar caps or hollow-cone beams from outer gaps, with pulse profiles shaped by viewing geometry relative to the magnetic axis.^[111] At higher energies, non-thermal mechanisms dominate, linking to particle acceleration in the magnetosphere or pulsar winds, though the transition lacks a fully coherent unified model.^[112] X-ray observations reveal both thermal blackbody components from heated polar caps on the neutron star surface and non-thermal power-law spectra from synchrotron or inverse Compton processes in the magnetosphere. Imaging X-ray Polarimetry Explorer (IXPE) data from 2025 on transitional pulsars indicate that relativistic pulsar winds power dominant energy outputs, with polarization revealing ordered magnetic fields and asymmetries in wind structures, consistent with shock-accelerated electrons.^[113]^[114] Gamma-ray spectra, surveyed extensively by the Fermi Large Area Telescope, peak in the 0.1–10 GeV range for most rotation-powered pulsars, with phase-aligned pulses tracing high-altitude curvature radiation or pair cascades, though spectral cutoffs vary sharply between objects.^[115]^[116] In binary pulsars, optical and ultraviolet emission often stems from non-thermal synchrotron radiation at intra-binary shocks, where the relativistic pulsar wind collides with the companion's stellar outflow, producing pulsed or modulated fluxes distinct from isolated pulsar emission.^[117] Across wavelengths, the pulsed fraction—quantified as (maximum - minimum)/(maximum + minimum) flux—generally rises with photon energy, from 10–50% in radio bands to approaching 100% in GeV gamma rays, implying emission from progressively higher altitudes or broader beam openings that evade single-altitude models.^[111]^[118] This energy-dependent variation empirically extends primary emission frameworks, necessitating multi-zone acceleration or wind contributions to reconcile observed spectral energy distributions without assuming uniform coherence.^[112]^[117]

Debates and Empirical Challenges

A 2017 study of pulsar PSR B1828-11 revealed inconsistencies between established models for glitching—sudden spin-ups attributed to superfluid vortex unpinning in the neutron star crust—and precession or wobbling, where the spin axis traces a cone, as gravitational influences from companions fail to reconcile both phenomena simultaneously.^[119] These timing irregularities, including glitches and stochastic noise, remain unexplained by standard magnetospheric models, with proposals like superfluid turbulence or unresolved microglitches offering partial but unverified resolutions, as recoveries in high-magnetic-field pulsars deviate from predictions.^[120] ^[121] Slot gap and polar cap models for high-energy emission face empirical challenges from phase lags between radio and gamma-ray pulses observed in Fermi-LAT data, where predicted alignments from accelerated particle gaps do not match the observed off-pulse emission or light curve asymmetries in many systems.^[122] Coherent curvature emission (CCE), invoked for radio production via bunched charges along curved field lines, struggles with polarization mismatches, as simulated linear polarization fractions and position angle swings fail to reproduce the high degrees (~50-100%) and S-shaped variations seen in observations without ad hoc adjustments.^[123] Unification of radio and X-ray emission mechanisms remains unresolved, with phase misalignments—such as X-ray pulses lagging radio by 0.1-0.3 cycles in PSR 1509-58—indicating distinct origins, contradicting models assuming co-spatial non-thermal processes in the magnetosphere.^[124] Force-free magnetosphere approximations, which neglect plasma inertia to simplify electrodynamics, encounter causal violations beyond the light cylinder and require local breakdowns for equilibrium, favoring empirical constraints on luminosities over such idealized constructs lacking direct validation.^[125] ^[126]

Scientific Applications

Precision Timing and Clocks

Pulsars, especially millisecond variants, function as extraordinarily stable rotational clocks, with their pulse arrival times enabling precision comparable to terrestrial atomic standards. The fractional frequency stability of select millisecond pulsars reaches approximately $10^{-15} over integration times of months to years, surpassing many hydrogen maser clocks in long-term performance.^[127] This stability arises from the pulsars' spin-down rates, which are modeled through polynomial fits to pulse phase, allowing residuals as low as tens of nanoseconds after accounting for astrometric, relativistic, and instrumental effects.^[128] A prominent example is PSR J1713+0747, whose timing residuals over two decades demonstrate root-mean-square (RMS) deviations of around 200 nanoseconds, supporting phase-connected solutions that track every rotation without ambiguity.^[127]^[129] These solutions rely on empirical modeling of pulse profile variations and interstellar effects to maintain coherence, yielding predictive ephemerides for pulse times-of-arrival (TOAs) with sub-microsecond accuracy over extended baselines.^[130] Such metrology underpins pulsar-based timekeeping, distinct from applications probing gravitational effects, by prioritizing raw rotational predictability. In pulsar timing arrays (PTAs), arrays of 20–100 millisecond pulsars, coordinated by efforts like the International Pulsar Timing Array (IPTA), aggregate TOAs to achieve ensemble stability for detecting nanohertz-scale gravitational wave backgrounds.^[131] The IPTA's joint analyses reveal correlated residuals at levels below 100 nanoseconds RMS per pulsar, limited by red noise from spin irregularities and profile fluctuations rather than white noise from measurement errors.^[132] Glitches, though rare in millisecond pulsars, introduce phase discontinuities— as observed in PSR J1713+0747 in 2021—necessitating re-phasing or multi-component models to restore long-term coherence.^[133] These arrays thus serve as interstellar clocks, with ongoing refinements in fitting algorithms enhancing ephemeris precision for future nHz detections.^[134] Pulsar-based navigation utilizes the precise timing of X-ray pulsar pulses to determine spacecraft position through triangulation, analogous to GPS but employing celestial sources. The Station Explorer for X-ray Timing and Navigation Technology (SEXTANT), integrated with the Neutron Star Interior Composition Explorer (NICER) instrument on the International Space Station, conducted the first in-space demonstration of autonomous X-ray pulsar navigation (XNAV) in November 2017.^[135]^[136] During the SEXTANT demonstration, real-time onboard processing of signals from four millisecond pulsars achieved navigation position accuracy of approximately 10 km in the worst direction, marking a shift from prior ground-based simulations to empirical, flight-validated unfolding of pulsar phase data.^[135]^[137] NICER, launched to the ISS on June 3, 2017, provided the X-ray detection capability, leveraging pulsars' microsecond-level pulse predictability for positioning without reliance on spacecraft ephemeris updates.^[138] This approach offers advantages over traditional GPS, including operation over galactic scales independent of artificial infrastructure, enabling autonomous deep-space navigation where satellite networks are infeasible.^[139]^[136] However, challenges persist, such as pulsar signal occultation by solar system bodies or interstellar material, which can interrupt observations, and the need for sufficient photon collection time due to low X-ray flux, limiting real-time updates in obscured fields.^[140]^[141] Ongoing developments emphasize multi-pulsar observation strategies to mitigate these issues for future missions beyond low Earth orbit.^[139]

Probes of Interstellar Medium

Pulsars enable detailed probing of the interstellar medium (ISM) through dispersive and scattering effects on their radio signals, which primarily reflect plasma properties along the line of sight rather than intrinsic pulsar emission characteristics. The dispersion measure (DM), defined as the integrated free electron column density DM = ∫ n_e dl from the pulsar to the observer, is determined from the quadratic frequency dependence of pulse arrival times, Δt ∝ DM / ν², where ν is the observing frequency.^[142] ^[143] This quantity facilitates tomographic reconstructions of Galactic electron density n_e, with models like YMW16 incorporating thousands of DM measurements to predict spatial variations, including enhancements from H II regions contributing up to hundreds of pc cm⁻³ along certain sightlines.^[144] ^[145] Interstellar scattering broadens pulses via multipath propagation in turbulent ionized plasma, with the scattering timescale τ_sc ∝ ν^{-4} for a Kolmogorov turbulence spectrum (power-law index β = 11/3), allowing inference of density fluctuation scales decoupled from pulsar distances.^[146] ^[147] Analysis of dynamic spectra and secondary spectra constrains inner and outer scales of turbulence, revealing a mix of Kolmogorov-like diffuse ISM scattering and steeper spectra near dense structures. In 2025, the Australian Square Kilometre Array Pathfinder (ASKAP) discovered two highly scattered pulsars, PSR J1646−4451 and PSR J1837−0616, with τ_sc values of 290 ms and 343 ms at ~1 GHz, respectively, among the most extreme known, indicating localized turbulent enhancements in the southern Galactic plane.^[148] ^[91] Rotation measures (RM = ∫ n_e B_∥ dl, with B_∥ the line-of-sight magnetic field) from pulsar polarization yield ISM magnetic field maps, with surveys of over 400 pulsars showing disk strengths of ~1–2 μG and spiral arm reversals.^[149] ^[150] HI 21-cm absorption spectra against pulsars probe cold neutral gas kinematics, establishing distance brackets via velocity crowding and detecting AU-scale structure through multi-epoch variability, as in recent Murriyang observations of PSR J1644−4559.^[151] Modern interferometric arrays like MeerKAT and ASKAP resolve scattering substructure and mitigate confusion in DM surveys, enabling precise n_e mapping across the Galaxy while isolating ISM effects from source-intrinsic dispersion.^[152]

Tests of General Relativity

Binary pulsar systems, where a pulsar orbits a compact companion, enable precise tests of general relativity (GR) through measurements of post-Keplerian orbital parameters that deviate from Newtonian predictions. These parameters include the rate of periastron advance (\dot{\omega}), the orbital period decay (\dot{P_b}) due to gravitational wave emission, and the Shapiro delay in pulse arrival times caused by gravitational time dilation and deflection. Pulsar timing achieves sub-microsecond precision, allowing empirical verification of GR's predictions against alternatives like scalar-tensor theories. The Hulse-Taylor binary pulsar PSR B1913+16, discovered in 1974, provided the first such test. Observations over decades measured the periastron advance at $2.828^\circ per year, matching GR's prediction within measurement uncertainties. The orbital decay rate \dot{P_b} was found to agree with GR's quadrupole formula for gravitational wave energy loss to within 0.2%, confirming the emission of gravitational waves as predicted by Einstein's theory. This measurement, based on timing data spanning more than 40 years, remains one of the cleanest verifications of GR in the strong-field regime, with no significant deviations observed. The double pulsar system PSR J0737-3039A/B, identified in 2003, offers even tighter constraints due to its relativistic orbit with a 2.4-hour period. Timing observations confirmed geodetic spin precession of the pulsars' axes, with pulsar B's spin vector precessing at a rate consistent with GR's prediction of 4.77 degrees per year, verified through changes in the eclipse duration and pulse polarization. Shapiro delay measurements in pulsar A's signals, delayed by the companion's gravitational field, yielded a shape parameter s and range r aligning with GR to within 0.1% after 16 years of data. These results rule out certain modified gravity theories at high confidence.^[153] In the triple system PSR J0337+1715, discovered in 2013 and comprising a millisecond pulsar with two white dwarf companions, timing data test the strong equivalence principle under strong self-gravitation. The inner 0.36-day orbit and outer 327-day orbit show no differential acceleration between the pulsar-white dwarf inner pair and the outer companion, constraining violations of the equivalence principle to less than $2 \times 10^{-6}, far tighter than solar-system tests. This limits alternative gravity models, such as those with strong scalar fields, by requiring any fifth force to be weaker than $10^{-5} times gravity's strength.^[154]^[154]

Gravitational Wave Astronomy

Pulsar timing arrays (PTAs), consisting of precisely timed millisecond pulsars, detect nanohertz-frequency gravitational waves (GWs) through correlated residuals in pulse arrival times, as predicted by general relativity's Hellings-Downs spatial correlation curve.^[155] In June 2023, the North American Nanohertz Observatory for Gravitational Waves (NANOGrav) reported evidence for an isotropic stochastic GW background using a 15-year dataset from 67 pulsars, with a Bayesian odds ratio exceeding 10^3 in favor of the GW signal over noise-only models.^[156] This signal, characterized by a power-law strain amplitude of h_c(f) \approx 2 \times 10^{-15} at 3 nHz and a spectral index near -2/3, aligns with expectations from a cosmic population of supermassive black hole binaries (SMBHBs) at galactic centers.^[157] Independent analyses from the International Pulsar Timing Array (IPTA), incorporating data from NANOGrav, the European PTA (EPTA), and others, corroborated this evidence in 2023, strengthening the case for a common low-frequency GW spectrum while ruling out certain alternative origins like cosmic strings at high confidence.^[158] ^[159] Ground-based detectors like LIGO and Virgo have searched for continuous, quasi-monochromatic GWs from rapidly rotating, asymmetric neutron stars hosting known pulsars, where emission arises from quadrupole deformations (ellipsoidal or "mountain" asymmetries).^[160] In the third observing run (O3, 2019-2020), targeted searches of 236 pulsars yielded no detections but set stringent upper limits on the GW strain amplitude h_0, such as h_0^{95\%} < 4.2 \times 10^{-26} for the Crab pulsar at 123 Hz, implying maximum equatorial ellipticities \epsilon < 10^{-8} for typical neutron star equations of state.^[160] These limits, derived from semi-coherent and hierarchical methods on O3 data, constrain internal magnetic field strengths and crust superfluid dynamics, tightening models of neutron star structure beyond electromagnetic observations alone.^[161] For accreting millisecond X-ray pulsars, O3 searches excluded GW luminosities exceeding 10^{-7} of rotational energy loss for 20 targets, challenging spin-up torque interpretations.^[162] Future space-based observatories like the Laser Interferometer Space Antenna (LISA), scheduled for launch in the 2030s, are projected to detect chirp signals from inspiraling compact binaries involving neutron stars, including those observable as pulsar systems in wider orbits.^[163] Simulations predict LISA could resolve thousands of galactic NS-NS binaries emitting in the millihertz band, with verification sources like low-eccentricity pulsar binaries providing templates for signal extraction and tests of inspiral waveforms against general relativity.^[163] These detections would extend pulsar-based GR verifications—such as orbital decay rates in systems like PSR B1913+16—to the strong-field regime, while multi-messenger follow-up with radio telescopes could confirm pulsar identities and measure post-inspiral remnants. Empirical upper bounds from ongoing PTA and CW searches continue to refine source population models, excluding overly efficient GW emitters and favoring astrophysical over exotic origins for the observed stochastic background.^[164]

Recent Surveys and Mapping

The Five-hundred-meter Aperture Spherical Telescope (FAST) Galactic Plane Pulsar Snapshot (GPPS) survey has significantly expanded the known pulsar population through targeted observations of the Galactic plane, with discoveries reported up to 2025 encompassing approximately 25% of the planned survey area. This effort yielded 107 rotating radio transients (RRATs) and 177 millisecond pulsars, providing insights into the distribution and demographics of transient and recycled neutron stars in dense interstellar environments.^[165] In a 2024 update, the survey identified 473 additional pulsars, including 137 millisecond pulsars and 30 RRATs, enhancing statistical models of Galactic pulsar luminosity and evolution.^[90] MeerKAT-based initiatives, such as the Transients and Pulsars with MeerKAT (TRAPUM) project, have complemented these findings by focusing on globular clusters and the Galactic bulge. In Terzan 5, a densely packed globular cluster, TRAPUM discovered 10 new millisecond pulsars in 2024, nearly doubling the cluster's known population and enabling refined constraints on cluster dynamics and binary formation rates.^[166] MeerKAT's high sensitivity has also facilitated reprocessing of archival data, uncovering transient pulsars in the Galactic plane and supporting population synthesis models for short-period sources. The Canadian Hydrogen Intensity Mapping Experiment (CHIME) has advanced all-sky pulsar detection via its All-sky Multiday Pulsar Stacking Search (CHAMPSS), initiated in 2025, which stacks multi-day observations to identify intermittent emitters across the northern sky. This approach targets faint, highly variable signals overlooked in single-epoch surveys, yielding preliminary discoveries of long-period transients and contributing to mappings of pulsar intermittency distributions.^[167] Concurrently, the Australian Square Kilometre Array Pathfinder (ASKAP) incoherent-sum transient survey has detected scattered pulsar-like signals in the Galactic plane, with 2024-2025 reanalyses of prior data revealing additional periodic sources through enhanced de-dispersion techniques. Polarization measurements from recent FAST and MeerKAT datasets have constrained emission beam geometries for hundreds of newly discovered pulsars, with 2024-2025 analyses of over 100 sources revealing orthogonal polarization modes and testing models of magnetospheric emission. These observations, spanning low to mid-frequencies, indicate a prevalence of nearly aligned rotator geometries in millisecond pulsars, informing evolutionary pathways from normal to recycled populations.^[168] Such surveys collectively map pulsar spatial distributions, highlighting concentrations in the inner Galaxy and enabling empirical tests of birth rates and selection effects in biased samples.^[169]

Notable Examples and Recent Discoveries

Archetypal Pulsars

The Crab Pulsar (PSR B0531+21), central engine of the Crab Nebula supernova remnant from the guest star observed in 1054 AD, exemplifies a young, rapidly rotating neutron star with a spin period of 33 milliseconds and a characteristic age of approximately 10,000 years, though its true dynamical age is about 970 years based on historical records.^[170] Its high spin-down luminosity, exceeding 10^31 erg/s, powers a bright pulsar wind nebula observable across radio to gamma-ray wavelengths, serving as a benchmark for models of magnetospheric particle acceleration and pair production in young pulsars.^[171] Observations confirm pulsed emission in X-rays and gamma rays, with the pulsar's non-thermal spectrum providing empirical constraints on acceleration mechanisms near the light cylinder.^[172] The Vela Pulsar (PSR J0835-4510 or PSR B0833-45), with a spin period of 89 milliseconds and characteristic age of around 11,000 years, represents an archetypal middle-aged pulsar known for its frequent rotational glitches—sudden spin-ups attributed to superfluid vortex dynamics in the stellar interior.^[173] These glitches, first noted in the 1970s and recurring irregularly every few years, offer key tests for neutron star interior models, with post-glitch recovery phases revealing exponential relaxation timescales of days to months.^[174] As one of the brightest gamma-ray sources among pulsars, Vela's emission spans over 80% of its period in high-energy bands, highlighting efficient magnetospheric gamma-ray production and bridging radio and high-energy pulse profiles for alignment studies.^[175] PSR B1919+21, the first pulsar discovered on November 28, 1967, by Jocelyn Bell Burnell using a Cambridge radio telescope, features a period of 1.337 seconds and narrow pulse width of about 0.04 seconds, establishing the prototype for periodic, lighthouse-like radio emission from rotating neutron stars.^[176] Its long-term stability, with minimal timing noise, has provided a foundational benchmark for pulsar timing techniques and early validations of neutron star models, despite its isolation and lack of associated supernova remnant.^[176] These canonical pulsars collectively anchor theoretical frameworks, from emission geometry to spin evolution, by offering datasets with precise periods, dispersion measures, and multi-wavelength profiles that calibrate population synthesis and evolutionary simulations.^[177]

Binary and Extreme Systems

Binary pulsar systems consisting of two neutron stars provide exceptional laboratories for testing general relativity due to their compact orbits and measurable orbital decay from gravitational wave emission. The first such system discovered, PSR B1913+16 (also known as the Hulse-Taylor binary), was identified in 1974 and features a 7.75-hour orbital period with high eccentricity of approximately 0.617. Observations of its pulse timing revealed an orbital shrinkage rate of 2.4 × 10^{-12} per year, precisely matching general relativity's prediction of energy loss via quadrupole gravitational radiation to within 0.2%, providing the first indirect evidence of gravitational waves.^[178]^[179] This system's parameters, including periastron advance and geodetic precession, further confirm relativistic effects, earning Russell Hulse and Joseph Taylor the 1993 Nobel Prize in Physics.^[180] The double pulsar PSR J0737−3039A/B, discovered in 2003, represents an even tighter extreme with a 2.45-hour orbital period and both components observable as radio pulsars, enabling precise measurements of phenomena like spin-orbit coupling and Shapiro delay. Timing data over 16 years have validated general relativity to better than 0.05% precision, including the prediction of orbital decay at a rate of 1.25 × 10^{-12} per year.^[181]^[153] The system's rapid orbital evolution projects a merger in approximately 85 million years, offering insights into neutron star equation-of-state constraints and gravitational wave progenitors.^[182] Magnetars, a subclass of pulsars characterized by magnetic fields typically exceeding 10^{14} gauss that power sporadic gamma-ray bursts and quiescent X-ray emission, exemplify extreme field strengths but face challenges from outliers like SGR 0418+5729. Discovered in 2009 via bursts akin to other soft gamma repeaters, this object exhibits a dipole magnetic field inferred below 7.5 × 10^{12} gauss from long-term X-ray monitoring, far lower than standard magnetar models requiring ultra-high fields for crustal cracking and burst triggering.^[183]^[184] This discrepancy suggests alternative mechanisms, such as multipolar field configurations or rapid rotator origins, may sustain magnetar-like activity without extreme dipolar fields, prompting revisions to formation theories linking high magnetism to dynamo amplification in proto-neutron stars.^[185] Spider pulsar systems, comprising black widows (with companions under 0.1 solar masses) and redbacks (0.1–1 solar mass companions), probe extreme mass-transfer and ablation in tight binaries where the pulsar's relativistic wind erodes the low-mass donor. These millisecond pulsars, recycled via accretion, exhibit eclipsing and variable pulses due to intrabinary shocks and companion geometry. The 2025 SpiderCat catalog compiles 111 such systems, including 50 black widows and 30 redbacks, facilitating statistical studies of evolutionary pathways from low-mass X-ray binaries and gamma-ray emission correlations.^[46] These interactions highlight causal dynamics of angular momentum transfer and orbital modulation, distinct from neutron star binaries' gravitational focus.^[47]

Discoveries from 2023-2025

In 2024, the Transients and Pulsars with MeerKAT (TRAPUM) survey discovered ten new millisecond pulsars in the globular cluster Terzan 5 using MeerKAT and Green Bank Telescope data, bringing the total known in this cluster to over 50 and highlighting its exceptional density of recycled neutron stars formed via dynamical interactions.^[186] These pulsars exhibit spin periods ranging from 2.5 to 33 milliseconds and low dispersions, consistent with origins in low-mass X-ray binaries, thereby refining models of pulsar recycling efficiency in core-collapsed globular clusters.^[166] The Five-hundred-meter Aperture Spherical Telescope (FAST) Galactic Plane Pulsar Snapshot survey, through reprocessing and targeted observations completed by November 2024, identified 473 new pulsars, including 137 millisecond pulsars and 30 rotating radio transients (RRATs), expanding the Galactic catalog and revealing a higher incidence of transients in the inner Milky Way than previously modeled.^[90] Earlier phases of the survey had already uncovered 107 RRATs and 177 millisecond pulsars by early 2025, with these sporadic emitters challenging detection thresholds and indicating bursty emission mechanisms driven by magnetospheric instabilities.^[165] In October 2025, the Australian Square Kilometre Array Pathfinder (ASKAP) Variables and Slow Transients survey detected two highly scattered pulsars, PSR J1646−4451 and PSR J1837−0616, via image-based searches that mitigated interstellar scattering effects, enabling identification of faint, broadened pulses at distances of approximately 5–10 kpc.^[91]^[148] These findings underscore ASKAP's sensitivity to dispersed populations obscured by multipath propagation, contributing to updated scattering models and population estimates for pulsars in the Galactic disk.^[91] NASA's Imaging X-ray Polarimetry Explorer (IXPE) in 2025 observed pulse-phase-dependent polarization asymmetries in accreting X-ray pulsars like 4U 1538−52, revealing non-uniform magnetic field geometries and unexpected off-pulse emission components inconsistent with simple dipole models.^[187] Such asymmetries, measured across multiple epochs totaling over 360 ks, imply complex accretion flows and cyclotron resonant scattering, providing empirical constraints on neutron star surface topologies. In September 2025, James Webb Space Telescope spectroscopy of the pulsar planet PSR B1257+12 b uncovered a carbon-dominated atmosphere (rich in C₂ and C₃ molecules) with evidence of strong westward winds, the first such characterization for a circumpulsar world and suggesting ablation-driven enrichment from the host neutron star's radiation.^[188] This observation updates survival models for planets in extreme radiation environments, indicating carbon fractionation enhances atmospheric retention against sputtering.^[189] These survey-driven advances collectively revise pulsar demographics, with FAST and ASKAP detections emphasizing transient and scattered subpopulations that comprise up to 10–20% of undiscovered Galactic sources, while globular and planetary system studies inform evolutionary pathways in dense or irradiated settings.^[90]^[91]

Open Questions and Future Directions

Unresolved Theoretical Issues

The precise mechanism responsible for the coherent radio emission from pulsars remains unresolved after over five decades of study, with leading models invoking curvature radiation or synchrotron maser processes in the magnetosphere failing to fully reproduce observed properties such as the high brightness temperatures exceeding 10^{25} K and the linear polarization characteristics.^[190] Theoretical frameworks struggle to explain the emission's origin without invoking poorly constrained plasma conditions or unverified wave-particle interactions that amplify incoherent radiation to coherent levels.^[191] Pulsar glitches, sudden spin-ups by fractions of 10^{-6} to 10^{-9} in rotation frequency, exhibit diverse behaviors across pulsars, but the triggering mechanisms—whether crustal starquakes releasing stored strain or sudden unpinning of superfluid vortices leading to angular momentum transfer—lack consensus, as neither fully accounts for the observed glitch sizes, recovery timescales, or rarity in young pulsars.^[192] Vortex avalanche models predict clustered glitches inconsistent with long-term Vela pulsar data, while starquake theories underestimate energy release without ad hoc adjustments to crustal rigidity.^[193] The equation of state (EOS) for supranuclear matter in neutron stars, probed via pulsar mass-radius relations, remains indeterminate beyond nuclear saturation density, with tensions between stiff EOS supporting 2 M_\sun pulsars like PSR J0740+6620 and softer models required for compatibility with gravitational wave constraints from binary mergers.^[5] Empirical data from pulsar timing yield only indirect bounds, leaving ambiguities in phase transitions to quark matter or hyperonic phases untested, as no unique EOS fits all multi-messenger observations without invoking hybrid compositions.^[194] Inconsistencies in pulsar magnetic field evolution challenge monotonic decay models, as observed braking indices deviating from the dipole value of 3 imply time-varying field strengths or geometries not captured by standard ohmic dissipation or Hall drift simulations.^[195] Long-term timing data reveal irregular spin-down rates uncorrelated with age, suggesting episodic field reconfiguration or burial by fallback accretion, yet simulations fail to predict the scatter in inferred surface fields from 10^{12} to 10^{14} G across populations.^[196] Pair production processes in pulsar magnetospheres, essential for populating accelerating gaps, operate near thresholds where attenuation lengths exceed polar cap sizes, but laboratory unverifiable quantum electrodynamic effects in curved fields lead to model-dependent multiplicities that underpredict gamma-ray efficiencies in young pulsars.^[197] Recent analyses derive lower limits on pair multiplicities from wind nebula spectra but cannot distinguish one-photon magnetic absorption from two-photon collisions without resolved spectral cutoffs.^[198] Hints of dark matter candidates from pulsar timing residuals, including 12 potential signals interpreted as compact objects modulating pulse arrivals in 2024 analyses, remain tentative due to insufficient distinction from instrumental noise or foregrounds, prioritizing further verification over causal attribution.^[199] These perturbations, if astrophysical, challenge halo models but lack corroboration from multi-pulsar baselines.^[200]

Prospects for New Observations

The Square Kilometre Array (SKA), with early operations anticipated in the late 2020s, is forecasted to expand the catalog of known pulsars by a factor of up to 10, potentially identifying over 20,000 new sources through wide-field, high-sensitivity radio surveys that prioritize millisecond and faint objects previously below detection thresholds.^[201] This influx would enable denser pulsar timing arrays for nanohertz gravitational wave detection and improved statistical constraints on galactic populations, though realization depends on commissioning timelines and data processing efficacy.^[202] In the very-high-energy regime, the Large High Altitude Air Shower Observatory (LHAASO) has demonstrated capability for pulsed detections, with projections for confirming signals from the Crab Pulsar within six years of sustained observation, while the Southern Wide-field Gamma-ray Observatory (SWGO), targeting deployment in the 2030s, could achieve pulsed detection of the Vela Pulsar in roughly one year due to its wide-field design optimized for southern hemisphere sources.^[203] These instruments may illuminate particle acceleration mechanisms in pulsar magnetospheres, extending spectra beyond current limits set by space-based telescopes like Fermi-LAT. Synergies in multi-messenger astronomy, such as rapid radio follow-up to gravitational wave alerts from upgraded LIGO/Virgo or future Einstein Telescope, hold potential for localizing pulsar-involved mergers and refining dispersion measure distances via joint timing.^[204] Machine learning techniques, including convolutional vision transformers and anomaly detection for single-pulse searches, are poised to sift vast SKA datasets for transients and weak candidates, accelerating identification amid rising data volumes.^[205] Collectively, these capabilities could sharpen interstellar medium mapping and general relativistic tests through larger, more precise samples, albeit with yields contingent on algorithmic robustness and instrumental performance.^[206]

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1974: the discovery of the first binary pulsar - IOPscience
Jun 1, 2015 · When Russell Hulse discovered PSR B1913+16 on 2 July 1974, he inscribed the comment 'fantastic!' on the discovery form because its 59 ms period ...
[18]
[PDF] The Discovery of the First Millisecond Pulsar: Personal Recollections
This article provides a first-hand account of the 1982 Arecibo observations that led to the discovery of PSR ... Arecibo Search of Pulsar Candidates for Pulses ...
[19]
Discovery of 10 pulsars in an Arecibo drift-scan survey
Abstract. We present the results of a 430-MHz survey for pulsars conducted during the upgrade to the 305-m Arecibo radio telescope. Our survey covered a to.
[20]
NASA's Fermi Mission Nets 300 Gamma-Ray Pulsars … and Counting
Nov 28, 2023 · NASA's Fermi Gamma-ray Space Telescope has discovered 294 gamma-ray-emitting pulsars, while another 34 suspects await confirmation.
[21]
Chiming In on the Pulsar Search: Searching for Pulsars with CHIME
Sep 12, 2025 · While more than 3,700 pulsars have been discovered to date, increasing this number will enable further exciting science.
[22]
The Nobel Prize in Physics 1974 - NobelPrize.org
The Nobel Prize in Physics 1974 was awarded jointly to Sir Martin Ryle and Antony Hewish for their pioneering research in radio astrophysics.
[23]
New Tools (Cosmology - American Institute of Physics.
Hewish received the Nobel Prize for his discovery of pulsating radio sources, called pulsars, although it was his student Jocelyn Bell who made the actual ...
[24]
Jocelyn Bell Burnell - StarChild - NASA
The telescope that Bell Burnell used to discover the first pulsar generated 121.8 meters of data every 4 days. How much information was generated on chart ...
[25]
The First Pulsar | astrobites
Sep 15, 2017 · Title: Observation of a Rapidly Pulsating Radio Source. Authors: A. Hewish, S. J. Bell, J. Pilkington, P. Scott, and R. Collins.Missing: confirmation | Show results with:confirmation
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Jocelyn Bell Burnell – Discovered Pulsars - Frontiers
Sep 22, 2022 · Jocelyn Bell Burnell discovered pulsars in 1967 while still a graduate student in radio astronomy at Cambridge. Her discovery became one of the ...
[27]
7 Nobel Prize Scandals | Britannica
Oct 13, 2025 · One of the perhaps best-known alleged slights concerned Jocelyn Bell Burnell, who discovered pulsars in 1967 and later published a paper with ...
[28]
Dame Jocelyn Bell Burnell: 'Did I feel cheated over the Nobel Prize ...
May 7, 2018 · Dame Jocelyn Bell Burnell: 'Did I feel cheated over the Nobel Prize? No. I know from another pulsar astronomer who won it that you get no peace.
[29]
In 1974, They Gave The Nobel To Her Supervisor. Now She's Won A ...
Sep 6, 2018 · "I feel I've done very well out of not getting a Nobel prize," she told the Guardian. "If you get a Nobel prize you have this fantastic week and ...
[30]
Q&A: Pulsar pioneer Jocelyn Bell Burnell - AIP Publishing
Jan 30, 2019 · She, however, says she doesn't hold a grudge against the Nobel committee. Last year, a half century after her first publication on pulsars, she ...Missing: controversy | Show results with:controversy
[31]
The different types of supernovae explained - Astronomy Magazine
Nov 8, 2023 · The progenitor stars of type II supernovae are massive enough to fuse elements up to iron. But once iron is reached, fusion ceases and the star ...
[32]
[PDF] Lecture 17: Supernovae and Neutron Stars - Lick Observatory
Progenitors heavier than 20 solar masses excluded at the. 95% confidence level. Presupernova stars – Type IIp and II-L. The solid line is for a Salpeter IMF ...
[33]
[PDF] Neutron Stars in Supernovae and Their Remnants - arXiv
Nov 16, 2010 · In the late 1960's, pulsars were discovered in the Crab Nebula and the Vela supernova remnant, proving the relationship between neutron star ...<|separator|>
[34]
Theoretical support for the hydrodynamic mechanism of pulsar kicks
Typical birth velocities range from ∼ 200 – 500 km s - 1 , with some reaching upwards of ∼ 1000 km s - 1 [2] . While the observed pulsar velocities may hint at ...
[35]
Pulsar Kick: Status and Perspective - MDPI
Monte Carlo simulations estimate the average birth velocity of pulsars to be around ∼(250–300) km/s, following a Maxwellian distribution with a dispersion of ...
[36]
Calibration of neutron star natal kick velocities to isolated pulsar ...
The associated supernova (SN) explosions eject matter at velocities of ∼ 10 000 km s−1 with a significant degree of asymmetry. Conservation of momentum implies ...
[37]
YOUNG CORE-COLLAPSE SUPERNOVA REMNANTS AND THEIR ...
The discovery of the pulsar in the Crab Nebula showed that neutron stars are born in core-collapse supernovae and that the. PWN (pulsar wind nebula) is ...
[38]
Pulsars: Three Years into a Mystery - NASA ADS
Pulsar in Crab Nebula; position is listed for the 16th magnitude optical pulsar. 0833. Pulsar associated with Vela-X supernova remnant. 1119. Radio emission ...
[39]
[astro-ph/0408004] Millisecond Pulsars in X-Ray Binaries - arXiv
Jul 30, 2004 · Despite considerable evidence verifying that millisecond pulsars are spun up through sustained accretion in low-mass X-ray binaries (LMXBs), it ...
[40]
Long-term evolution of spin and other properties of neutron star low ...
A neutron star (NS) accreting matter from a companion star in a low-mass X-ray binary (LMXB) system can spin up to become a millisecond pulsar (MSP).
[41]
Testing the accretion-induced field-decay and spin-up model for ...
Millisecond radio pulsars have long been proposed to form from a spin-up recycling process in a binary system. In this paper, we demonstrate that the ...
[42]
The Origin of Millisecond Pulsars - NASA ADS
... binary system (Radhakrishnan and Srinivasan 1982). The spin-up process (also called recycling) can achieve a very short spin period if the stellar magnetic ...
[43]
Cosmic Recycling of Millisecond Pulsars - NASA/ADS
We compare the rotation rate of neutron stars in low-mass X-ray binaries (LMXBs) with the orbital period of the binaries.Missing: mechanisms | Show results with:mechanisms
[44]
[1302.2914] The double pulsar: evidence for neutron star formation ...
Feb 12, 2013 · We find the recycled pulsar in this system, PSR J0737-3039A, to be a near-orthogonal rotator, with an average separation between its spin and ...
[45]
THE DOUBLE PULSAR: EVIDENCE FOR NEUTRON STAR ...
ABSTRACT. The double pulsar system PSR J0737−3039A/B is a double neutron star binary, with a 2.4 hr orbital period, which has allowed measurement of ...
[46]
Spin period evolution of a recycled pulsar in an accreting binary
We investigate the spin period evolutions of recycled pulsars in binary accreting systems. Taking both the accretion induced field decay and spin-up into ...
[47]
SpiderCat: A Catalog of Compact Binary Millisecond Pulsars - arXiv
May 16, 2025 · As of this initial release, SpiderCat contains 111 entries: 30 redbacks, 50 black widows, 2 huntsmans, 23 redback candidates, 5 black widow ...
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New catalog compiles more than 100 'spider' pulsars that consume ...
Sep 25, 2025 · In an article published on the arXiv preprint server, they present more than 100 of them in a database. This database is called SpiderCat, which ...
[49]
Astronomers detect a new black-widow pulsar - Phys.org
Sep 18, 2025 · An international team of astronomers reports the discovery of a new "spider" millisecond pulsar, which received designation PSR J1544−2555.
[50]
4FGL J1544.2−2554: A new spider pulsar candidate
A considerable number of the MSPs are so-called spider pulsars, which are divided into the 'redback' (RB) and 'black widow' (BW) subclasses (Roberts 2013; ...
[51]
[PDF] Pulsar Spin Down Luminosity
The magnetic dipole radiation of known pulsars, based on observed rotational rates, has relatively low frequency. This frequency is not high enough to be ...
[52]
Small glitches and other rotational irregularities of the Vela pulsar
Glitches are sudden increases in the rotation rate ν of neutron stars, which are thought to be driven by the neutron superfluid inside the star. The Vela pulsar ...3. Pulsar Timing · 5. Results · 6. Timing Noise
[53]
[2011.07927] Flickering of the Vela pulsar during its 2016 glitch - arXiv
Nov 16, 2020 · This implies the energy reservoir built up between glitches is not released suddenly, but over a period of minutes to hours around the time of ...
[54]
[2207.04723] Pulsar death line revisited -- II. 'The death valley' - arXiv
Jul 11, 2022 · In this paper, which is the second in a series of papers, we analyse what parameters can determine the width of the radio pulsar 'death valley' in the P-{\dot ...Missing: statistical cutoffs
[55]
[PDF] Luminosity of a radio pulsar and its new emission death line
1). However, from Figure 1, we find that 37 pulsars are observed below the death line, including the long- period pulsar J0250+5854 (P = 23.5 s, Tan et al.Missing: dot | Show results with:dot
[56]
Young pre-low-mass X-ray binaries in the propeller phase
During this propeller phase, the disk matter at the magnetospheric boundary is shock-heated as the ``vanes'' of the supersonic propeller (IS75) hit it, and the ...
[57]
https://www.sciencedirect.com/topics/physics-and-astronomy/rotation-powered-pulsars
[58]
Rotation Powered Pulsars - an overview | ScienceDirect Topics
Rotation powered pulsars lose a large amount of energy with rotational deceleration, and part of the energy is used for the acceleration of radiating particles.
[59]
New insights into Pulsar Physics
Feb 17, 2016 · Pulsar periods and period derivatives can be used to estimate physical parameters such as characteristic age, magnetic field, and rate of energy ...
[60]
[PDF] Rotation-powered pulsars
For example, these formulae imply that the pulsar in the Crab Nebula has a magnetic field Bp ≈ 5 × 1012 G (for sin α = 1) and a characteristic age of ∼ 1200 yr.
[61]
[PDF] Evolution of Spin Period and Magnetic Field of the Crab Pulsar - arXiv
Dec 9, 2022 · Note: The Crab pulsar real B-field B = 3.3 × 1012 G and maximum characteristic age Tcmax = Tco/ fo = b−1 ≃ 10 kyr. The pulsar observable ...
[62]
Pulsar Characteristic Age | COSMOS
In 2007 the Crab pulsar had a period of 0.0331 sec and a period derivative of 4.22×10-13s/s. The characteristic age is around 1240 years. The supernova that ...
[63]
The Galactic population of canonical pulsars
In this paper, we aim to constrain the observed population of the canonical neutron star period, its magnetic field, and its spatial distribution at birth.
[64]
A New X-Ray Census of Rotation Powered Pulsars - IOP Science
Mar 3, 2025 · There are currently ∼3630 RPPs in the Australia Telescope. National Facility (ATNF) Pulsar Catalogue (version 2.3.0,. R. N. Manchester et al.
[65]
Binary and Millisecond Pulsars - PMC - PubMed Central
A growing fraction of the observed sample are the so-called “millisecond pulsars”, which have spin periods primarily in the range 1.5 and 30 ms and have rates ...
[66]
The ATNF Pulsar Catalogue
This section contains a set of checkboxes representing each pulsar parameter that you wish to display when querying the catalogue.Download · Glitch table · History · Feedback
[67]
Recycled pulsar - Oxford Reference
Recycled pulsars are believed to be ordinary pulsars which have lost energy and faded out, and then been spun up again by accretion of gas from a companion star ...Missing: characteristics | Show results with:characteristics
[68]
The 42 millisecond radio pulsars in 47 Tucanae - MPIFR Bonn
The total number of pulsars known in 47 Tuc is now 42. Here are the pulse profiles of the first 25. Fig. 1: Pulse profiles for 25 pulsars in 47 Tuc at 20 cm.
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[1307.2146] X-ray Observations of Disrupted Recycled Pulsars - arXiv
Jul 8, 2013 · Abstract:We present a Chandra X-ray survey of the disrupted recycled pulsars (DRPs), isolated radio pulsars with P > 20 ms and B_s < 3E10 G.
[70]
X-RAY OBSERVATIONS OF DISRUPTED RECYCLED PULSARS
We present a Chandra X-ray survey of the disrupted recycled pulsars (DRPs), isolated radio pulsars with P > 20 ms and Bs < 3 × 1010 G.
[71]
Double and single recycled pulsars: an evolutionary puzzle?
Since recycled pulsars are believed to form through accretion and spin-up in close binaries, the isolated objects presumably originate from disrupted ...
[72]
[1304.4825] Pulsars and magnetars - arXiv
Apr 17, 2013 · The high-energy sources known as anomalous X-ray pulsars (AXPs) and soft gamma-ray repeaters (SGRs) are well explained as magnetars: isolated neutron stars.
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A new theory of magnetar formation - MPA Garching
Feb 29, 2020 · We thus infer that magnetars have a dipole magnetic field of the order of 1015 Gauss (G), i.e. up to 1000 times stronger than typical neutron ...
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RXTE Observations of SGR 1806-20 Giant Flare December 27, 2004
The oscillations began three minutes after a titanic explosion on SGR 1806-20 that, for only a tenth of a second, released more energy than the Sun emits in ...
[75]
[0706.4156] Glitches in Anomalous X-ray Pulsars - arXiv
Jun 28, 2007 · These observations are challenging to interpret in standard glitch models, as is the frequent occurence of large glitches given AXPs' high ...Missing: characteristics | Show results with:characteristics
[76]
glitch and an anti-glitch in the anomalous X-ray pulsar 1E 1841–045
In addition, sudden increases in the angular velocity (i.e. glitches) have been observed in several AXPs. However, the properties of glitch events in AXPs are ...
[77]
MAGNETARS VERSUS HIGH MAGNETIC FIELD PULSARS
Our results allowed us to establish that there is no fundamental difference among apparently different manifestations of the objects (such as “AXPs” and “SGRs”) ...
[78]
Magnetars from magnetized cores - Oxford Academic
If magnetars are born with their high-surface magnetic fields, then, after a flare, one would expect a decrease in the magnetic field and energy of the magnetar ...
[79]
Polarimetric evidence of a white dwarf pulsar in the binary system ...
Dec 9, 2016 · ... white dwarf, power the observed polarized and non-polarized emission. AR Scorpii is therefore the first example of a white dwarf pulsar.
[80]
Mysterious white dwarf pulsar discovered - NASA Science
Feb 6, 2017 · The white dwarf in AR Sco is the size of Earth but 200,000 times more massive, and is in a 3.6 hour orbit with a cool star one third the mass of ...
[81]
Matter ejections behind the highs and lows of the transitional ...
Transitional millisecond pulsars are an emerging class of sources that link low-mass X-ray binaries to millisecond radio pulsars in binary systems. These ...
[82]
Matter Ejections Explain Peculiar High-Low Mode Switches in ...
Aug 30, 2023 · The millisecond pulsar PSR J1023+0038 is known to switch between two brightness modes almost constantly, something that until now has been an enigma.
[83]
New insights into rare pulsar - Oxford Physics
Jul 15, 2025 · 'Transitional millisecond pulsars are natural laboratories for studying how neutron stars evolve in binary systems,' said Dr Maria Cristina ...
[84]
[2509.04558] A carbon-rich atmosphere on a windy pulsar planet
Sep 4, 2025 · One such object, PSR J2322-2650b, uniquely resembles a hot Jupiter exoplanet due to its minimum density of 1.8 g/cm^3 and its ~1900 K ...
[85]
PSR J2322-2650 b - NASA Science
PSR J2322-2650 b is a gas giant exoplanet that orbits an unknown-type star. Its mass is 0.7949 Jupiters, it takes 0.3 days to complete one orbit of its star.
[86]
JWST Finds An Exoplanet Around A Pulsar Whose Atmosphere Is ...
Sep 11, 2025 · Circulation models predict that rapidly rotating planets, like PSR J2322-2650b, would have strong westerly winds, which is different from the ...
[87]
A new pulsar searching package - I. A high performance folding ...
PulsarX is a high-performance folding program for pulsar surveys, optimizing candidate folding with efficient de-dispersion and parameter optimization.
[88]
[PDF] Pulsar Observations - NCRA-TIFR
There are two main methods used for dedispersion – incoherent dedispersion and co- herent dedispersion. In incoherent dedisperion, which is a post-detection ...
[89]
An investigation of pulsar searching techniques with the fast folding ...
We present an in-depth study of the behaviour of the fast folding algorithm (FFA), an alternative pulsar searching technique to the fast Fourier transform (FFT ...Missing: dedispersion | Show results with:dedispersion
[90]
China's FAST Telescope Identifies over 1000 Pulsars
Nov 27, 2024 · China's FAST Telescope Identifies over 1,000 Pulsars · An aerial drone photo taken on Sept. 25, 2024 shows China's Five-hundred-meter Aperture ...
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[2411.15961] The FAST Galactic Plane Pulsar Snapshot survey - arXiv
Nov 24, 2024 · Here we report the discovery of 473 new pulsars from the FAST GPPS survey, including 137 new millisecond pulsars and 30 new RRATs.
[92]
Two highly scattered pulsars discovered with ASKAP - Phys.org
Oct 2, 2025 · Astronomers report the discovery of two new highly scattered pulsars as part of the Australian SKA Pathfinder (ASKAP) Variables and Slow ...
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[2404.16263] New Timing Results of MSPs from NICER Observations
Apr 25, 2024 · Using six years of observations from the Neutron Star Interior Composition Explorer (NICER), we have conducted an in-depth analysis of the X-ray timing results ...
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The Neutron Star Interior Composition Explorer Mission - HEASARC
NICER studies neutron stars using soft X-ray timing, enabling rotation-resolved spectroscopy to probe interior structure and exotic matter.NICER Mission Overview · NICER Data Analysis · NICER Archive · NICER News
[95]
Scattering Study of Pulsars below 100 MHz Using LWA1 - IOPscience
Interstellar scattering causes pulsar profiles to grow asymmetrically, thus affecting the pulsar timing residuals, and is strongest at lower frequencies.Missing: challenges | Show results with:challenges
[96]
Pulsar nulling and mode changing - Oxford Academic
This pulsar has a high DM and the pulse profile is significantly affected by interstellar scattering (Kramer et al. 2003). It is quite weak, and 60 s ...Missing: challenges | Show results with:challenges
[97]
Old Data, New Tricks Discover Pulsar in Galactic Plane
Jul 3, 2024 · A team of astronomers has found a new tool to discover pulsars. Pulsars are rapidly rotating neutron stars that blast out pulses of radiation at regular ...Missing: AI machine learning
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[1903.07644] Multi-Messenger Astrophysics with Pulsar Timing Arrays
Mar 18, 2019 · Pulsar timing arrays (PTAs) are on the verge of detecting low-frequency gravitational waves (GWs) from supermassive black hole binaries (SMBHBs) ...
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On this date: The first pulsar - ABC27
Nov 28, 2023 · On November 28, 1967, astronomy graduate student Jocelyn Bell noticed a regular radio pulse picked up by the newly built Interplanetary Scintillation Array.
[100]
Catalog of 558 pulsars - Astrophysics Data System
We strongly recommend that for all new pulsar discoveries, J2000 names of the form PSR Jhhrnrn±ddmm should be used, as recommended by the International ...
[101]
THE AUSTRALIA TELESCOPE NATIONAL FACILITY PULSAR ...
In accordance with. IAU specifications,1 names must explicitly include the equinox letter, e.g., PSR B0833 45 or PSR J0835 4510. Note, however, that positions ...
[102]
ATNFPULSAR - ATNF Pulsar Catalog - HEASARC - NASA
The Australia Telescope National Facility (ATNF) Pulsar Catalog is a catalog of known pulsars compiled by R.N. Manchester et al. and is descended from pulsar ...
[103]
Radio Pulsar Searches | Einstein@Home
Radio pulsar searches use a "blind search" to find neutron stars with strong magnetic fields, using large telescopes and "dedispersion" to correct for radio ...
[104]
THE EINSTEIN@HOME SEARCH FOR RADIO PULSARS AND PSR ...
This paper presents a detailed description of the search for new radio pulsars using Pulsar ALFA survey data from the Arecibo Observatory. The enormous ...
[105]
High-energy emission from pulsars in polar-cap models with ...
For a subclass of polar-cap models based on electromagnetic cascades induced by curvature radiation (CR) we calculate broad-band high-energy spectra of pulsed ...
[106]
A Model for Pair Production Limit Cycles in Pulsar Magnetospheres
Jul 16, 2024 · We develop a simplified time-dependent kinetic model of e ± pair cascades in pulsar magnetospheres that can reproduce the limit-cycle behavior of pair ...
[107]
One-photon pair production in pulsars: non-relativistic and ...
There are thresholds at which the pair production rate is singular for every value of j, k. In the asymptotic limit j, k are treated as continuous numbers and ...
[108]
Radio emission regions in pulsars - Oxford Academic
We study the concept of radius-to-frequency mapping using a geometrical method for the estimation of pulsar emission altitudes. The semi-empirical ...
[109]
Wide-band, low-frequency pulse profiles of 100 radio pulsars with ...
Nonetheless, in general our observations confirm the widening of pulsar profiles at low frequencies, as expected from radius-to-frequency mapping or ...
[110]
Brightness Temperature Constraints on Coherent Processes in ...
Aug 26, 2021 · In case of pulsars and FRBs the brightness temperatures reach values in excess of 1035 K (e.g.,Manchester & Taylor 1977; Melrose 2000; Lorimer ...
[111]
Polarized curvature radiation in pulsar magnetosphere
The polarized waves are generated through curvature radiation from the relativistic particles streaming along curved magnetic field lines and corotating with ...Missing: theories | Show results with:theories
[112]
Frequency resolved radio and high-energy emission of pulsars - arXiv
Nov 30, 2020 · In this paper, we compute pulsars multi-wavelength phase-resolved light-curves and spectra assuming that curvature radiation operates from inside the ...
[113]
Modeling the Multi-wavelength Radiation Properties in Pulsar ... - arXiv
Mar 10, 2024 · The multiwavelength light curves and spectra are computed by using the multiple emission mechanisms of both the primary particles ...
[114]
NASA's IXPE Imager Reveals Mysteries of Rare Pulsar
Jul 15, 2025 · Astronomers with NASA's IXPE have uncovered new evidence to explain how pulsing remnants of exploded stars interact with surrounding matter ...<|separator|>
[115]
[2412.13260] Polarized multiwavelength emission from pulsar wind
Dec 17, 2024 · The study found polarized emission in a transitional millisecond pulsar, originating from synchrotron radiation at the shock where pulsar wind ...
[116]
The Third Fermi Large Area Telescope Catalog of Gamma-ray Pulsars
Jul 20, 2023 · Abstract:We present 294 pulsars found in GeV data from the Large Area Telescope (LAT) on the Fermi Gamma-ray Space Telescope.
[117]
[PDF] 3PC: The Third Fermi-LAT Catalog of Gamma-Ray Pulsars
As a consequence, pulsars emit most of their power in the. 0.1–10 GeV band, with sharply-peaked MSPs concentrated in the higher decade. • The majority of ...
[118]
[2505.08567] Modelling the multi-wavelength emission and ... - arXiv
May 13, 2025 · The main aim of this work was to develop a general emission code to concurrently model the emission maps, light curves, and spectra at various orbital phases ...
[119]
The X-ray pulsar A0535 + 26 - Pulse profile and its time variability in ...
Figure 3a shows that the pulsed fraction increases significantly with energy, reaching possibly 100% at 100 keV. To verify this result, a different approach was ...
[120]
Study calls into question theories on pulsar phenomena
Jul 4, 2017 · Researchers at the University of Southampton have cast doubt over established explanations for certain behaviours in pulsars.Missing: slot gap phase lags
[121]
Timing irregularities and glitches from the pulsar monitoring ...
Glitches are discrete events consisting of a sudden change in rotation frequency, most often accompanied by a sudden change in the frequency derivative, which ...2.2. Pulsar Timing · 4. Results · 4.2. Psr J0835--4510
[122]
[PDF] Pulsar glitches: observations and physical interpretation
Hence it is possible that at least some of the reported magnetar anti-glitches are due to timing noise, and likely of magnetospheric origin. Radiative.
[123]
Pulsar Polar Cap and Slot Gap Models: Confronting Fermi Data
I will review acceleration and gamma-ray emission from the pulsar polar cap and slot gap. Predictions of these models can be tested with the data set on pulsars ...Missing: 2017 Southampton phase lags
[124]
Coherent Curvature Radio Emission and Polarization from Pulsars
Apr 28, 2021 · The mystery of coherent radio emission from pulsars is worth solving, as it resolves one of the outstanding problems in pulsar astronomy.
[125]
X-ray and radio pulse phase comparison for PSR 1509 - 58
The alignment of the optical and X-ray pulses is unknown, and so far ... phases of the X-ray and radio pulses on emission from the pulsar. The X-ray ...Missing: misalignment | Show results with:misalignment
[126]
Some Limitations on the Force-free Approximation to the Physics of ...
It is shown that any solution of the force-free equations describing axisymmetric pulsar magnetospheres has, beyond the light cylinder, properties which bring ...Missing: criticisms | Show results with:criticisms
[127]
An idealized pulsar magnetosphere: the relativistic force-free ...
We conclude that, in all cases, the equilibrium conditions for this model will require at least a local breakdown in force-free conditions. In analogous non- ...Missing: challenges | Show results with:challenges
[128]
Timing stability of millisecond pulsars and prospects for gravitational ...
Specifically, Hotan, Bailes & Ord (2006) presented a timing rms of 200 ns over 2 years of timing on PSRs J1713+0747 and J1939+2134 (PSR B1937+21) and 300 ns ...
[129]
A CASE STUDY OF PSR J1713+0747 - IOPscience
We conclude that when pulse-shape changes dominate timing errors, the timing precision of PSR J1713+0747 can be only improved by averaging over a larger number ...
[130]
Pulse Intensity Modulation and the Timing Stability of Millisecond ...
We show that changes in amplitude, shape, and pulse phase for the millisecond pulsar J1713+0747 cause this excess error.
[131]
[PDF] From search data to phase-connected timing solution Emilie Parent
A timing solution that is phase- connected is a model that accounts for every pulsar rotation. The model solution can predict with high-precision when a pulse ...
[132]
International Pulsar Timing Array second data release: Search for an ...
Jan 19, 2022 · Future international data releases will deliver increased sensitivity to gravitational wave radiation, and significantly increase the detection ...
[133]
Long-term stability estimation of ensemble pulsar timescales with ...
The primary objective of IPTA is to detect and characterize low-frequency gravitational waves by timing approximately 100 millisecond pulsars (MSPs) ...
[134]
Ultra-Wideband Polarimetry of the April 2021 Profile Change Event ...
Sep 23, 2025 · The millisecond pulsar PSR J1713+0747 is a high-priority target for pulsar timing array experiments due to its long-term timing stability, and ...
[135]
Towards robust gravitational wave detection with pulsar timing arrays
Precision timing of highly stable millisecond pulsars is a promising technique for the detection of very low frequency sources of gravitational waves.
[136]
[PDF] SEXTANT X-ray Pulsar Navigation Demonstration
The primary performance goal of the SEXTANT mission is to achieve real-time, onboard, navigation position accuracy of 10 km worst-direction, using up to two ...
[137]
NASA Team First to Demonstrate X-ray Navigation in Space
Jan 11, 2018 · With these predictable pulsations, pulsars can provide high-precision timing information similar to the atomic-clock signals supplied through ...<|separator|>
[138]
NASA team first to demonstrate X-ray navigation in space - Phys.org
Jan 11, 2018 · In the SEXTANT demonstration that occurred over the Veteran's Day holiday in 2017, the SEXTANT team selected four millisecond pulsar targets— ...<|separator|>
[139]
ISS: NICER/SEXTANT (Neutron-star Interior Composition ExploreR ...
Feb 1, 2016 · SEXTANT will demonstrate pulsar-based navigation for the first time in space. • NICER was launched to the International Space Station on 3 June.
[140]
[PDF] A High-Fidelity Performance and Sensitivity Analysis of X-ray Pulsar ...
Feb 7, 2022 · • Studied XNAV-based nav and timing for three challenging scenarios. – ISS-like LEO, Highly Inclined GEO (HI-GEO), and Lunar-Gateway-like ...
[141]
Review of X-ray pulsar spacecraft autonomous navigation
This paper focuses on the advances of the key techniques supporting XNAV, including the navigation pulsar database, the X-ray detection system, and the pulse ...
[142]
A novel method for rapidly simulating X-ray pulsar signals at a ...
Jan 1, 2025 · This paper addresses the challenges posed by the low photon flux and limited atmospheric penetration capabilities of X-ray pulsar signals, which ...
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[PDF] 3. dispersion and scintillation - Pulsars and Supernovae II
DISPERSION AND SCINTILLATION. 9. Pulsars as probes of the interstellar medium. • The dispersion measure to pulsars can be used to help map the galactic ...
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The frequency evolution of interstellar pulse broadening from radio ...
The pulsar signal traversing the ISM suffers interstellar dispersion quantified in terms of dispersion measure, DM, which is the integrated electron column ...
[145]
Tomography of the Galactic free electron density with the Square ...
We present a new algorithm for reconstructing the Galactic free electron density from pulsar dispersion measures. The algorithm.
[146]
Implications for Galactic Electron Density Structure from Pulsar ...
Oct 1, 2024 · We show that H ii regions can contribute tens to hundreds of parsecs per cubic centimeter in electron column density along a pulsar line of sight.
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[1610.03011] Scatter broadening of pulsars and implications on the ...
Oct 10, 2016 · Observations reveal a uniform Kolmogorov turbulence throughout the diffuse ionized interstellar medium (ISM) and supersonic turbulence ...
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SCATTER BROADENING OF PULSARS AND IMPLICATIONS ON ...
We find that the pulsars with low DMs are primarily scattered by the Kolmogorov turbulence, while those at low Galactic latitudes with high DMs undergo more ...
[149]
Discovery of Two Highly Scattered Pulsars from Image-Based ... - arXiv
We report the discovery and timing of two pulsars from a sample of four circularly polarized sources identified in radio continuum images taken ...
[150]
https://iopscience.iop.org/article/10.1086/501444/pdf
[151]
PULSAR ROTATION MEASURES AND THE LARGE-SCALE ...
ABSTRACT. The large-scale magnetic field of our Galaxy can be probed in three dimensions using Faraday rotation of pulsar signals.
[152]
Tiny-Scale Properties within the Interstellar Medium towards PSR ...
Mar 12, 2025 · We investigated HI absorption toward a single pulsar, PSR J1644-4559, and its variability over timescales from days to years, using Murriyang, ...
[153]
The Thousand-Pulsar-Array programme on MeerKAT–XVI. Mapping ...
First, dispersion of the pulsar signal provides an independent estimate of the electron column density, so that the average magnetic field strength itself can ...
[154]
Strong-Field Gravity Tests with the Double Pulsar | Phys. Rev. X
Dec 13, 2021 · Continued timing observations of the double pulsar PSR J0737–3039A/B, which consists of two active radio pulsars (A and B) that orbit each ...
[155]
An improved test of the strong equivalence principle with the pulsar ...
The best limit on the validity of SEP under strong-field conditions was obtained with a unique pulsar in a triple stellar system, PSR J0337+1715.
[156]
Evidence for a Gravitational-Wave Background - NANOGrav
NANOGrav has found evidence for a distinctive pattern of correlated timing deviations, agreeing with the predictions of general relativity.
[157]
The NANOGrav 15-year Data Set: Evidence for a Gravitational-Wave ...
Jun 28, 2023 · We report multiple lines of evidence for a stochastic signal that is correlated among 67 pulsars from the 15-year pulsar-timing data set ...
[158]
Search for Gravitational Waves from Individual Supermassive Black ...
The gravitational wave background signature in the NANOGrav 15-year data set raises the question of what might be producing this signal.
[159]
[2309.00693] Comparing recent PTA results on the nanohertz ... - arXiv
Sep 1, 2023 · Abstract page for arXiv paper 2309.00693: Comparing recent PTA results on the nanohertz stochastic gravitational wave background.
[160]
The second data release from the European Pulsar Timing Array III ...
Jun 28, 2023 · We present the results of the search for an isotropic stochastic gravitational wave background (GWB) at nanohertz frequencies using the second data release of ...
[161]
Searches for Gravitational Waves from Known Pulsars at Two ...
We present a targeted search for continuous gravitational waves (GWs) from 236 pulsars using data from the third observing run of LIGO and Virgo (O3)
[162]
Deep search of the full O3 LIGO data for continuous gravitational ...
Section IV presents the results of the search, which are upper limits on the gravitational wave strain amplitude vs frequency, along with derived, model ...
[163]
Search for continuous gravitational waves from 20 accreting ... - arXiv
Sep 20, 2021 · Abstract page for arXiv paper 2109.09255: Search for continuous gravitational waves from 20 accreting millisecond X-ray pulsars in O3 LIGO data.
[164]
Predictions for BHBH, BHNS, and NSNS Binaries Detectable with LISA
Oct 4, 2022 · Each binary loses orbital energy to gravitational waves throughout its lifetime. ... The joint detection of a binary pulsar with LISA and the SKA ...
[165]
The NANOGrav 15-year Gravitational-Wave Background Methods
Jun 28, 2023 · Pulsar timing arrays (PTAs) use an array of millisecond pulsars to search for gravitational waves in the nanohertz regime in pulse time of ...
[166]
FAST and Furious: Pulsar Discoveries from the World's Largest ...
Feb 1, 2025 · To date, with just under 25% of the total survey area completed, the discoveries include 107 rotating radio transients (RRATs), 177 millisecond ...
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Discovery and timing of ten new millisecond pulsars in the globular ...
Mar 26, 2024 · We report the discovery of ten new pulsars in the globular cluster Terzan 5 as part of the Transients and Pulsars with MeerKAT (TRAPUM) Large Survey Project.
[168]
CHIME All-sky Multiday Pulsar Stacking Search (CHAMPSS) - arXiv
Apr 22, 2025 · We describe the CHIME All-sky Multiday Pulsar Stacking Search (CHAMPSS) project. This novel radio pulsar survey revisits the full Northern Sky ...Missing: ASKAP 2024
[169]
Data From FAST and MeerKAT Surveys As a Test of Radio Pulsar ...
The data from the FAST and MeerKAT surveys has significantly increased the number of radio pulsars for which the polarization characteristics of their mean ...Missing: 2023-2025 CHIME ASKAP
[170]
Millisecond Pulsar Discoveries in an Image-based MeerKAT Survey ...
Sep 24, 2025 · We report on the follow-up observations of circularly polarized sources identified in the MeerKAT image-based survey of the Galactic bulge.
[171]
[PDF] The Crab Pulsar from HE to VHE
Remnant of historic supernova in 1054 A.D.. ○. Distance 2 kpc. ○. One of the most energetic pulsars 4.6 ...
[172]
[PDF] £s3 F% /o
pulsar. (other than its age), however, its non-thermal nebular emission is a much smaller fraction of the pulsar spin-down luminosity than it is in the Crab.Missing: key | Show results with:key
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[PDF] 7-Ray Pulsars: Radiation Processes in the Outer Magnetosphere
We show how pair production on thermal surface flux can limit the acceleration zones; estimates for the efficiency of GeV photon production 77^ and the 7-ray ...
[174]
[PDF] 19830023297.pdf
It must be pointed out, however, that no observed pulsar .has a period as long as 8 s and if the 5 March burst is associated with N49, whose age is -10 4 years ...<|separator|>
[175]
Period Irregularities in Pulsars
I. INTRODUCTION The first indication that pulsar periods are subject to unpredictable variations was the abrupt spin-up observed in the Vela pulsar (PSR ...Missing: archetypal | Show results with:archetypal
[176]
[PDF] the vela-x pulsar wind nebula revisited with four years of fermi large ...
Previous analyses of its γ-ray properties using Fermi-LAT observations have shown that magnetospheric emission is observed over 80% of the pulsar period (Abdo ...
[177]
Gravity experiments with radio pulsars - arXiv
Jul 23, 2024 · The first radio pulsar, then known as CP 1919 (now known as PSR B1919+21) showed an extraordinarily stable pulsation period of 1.3372795 ± 0. ...
[178]
[PDF] The Crab and Vela Pulsars - Cambridge University Press
9.4 The Vela Pulsar, PSR B0833−45. 129 the pulsar were so strong that they immediately showed their periodicity of 89 ms on the pen chart recordings (Large ...
[179]
Press release: The 1993 Nobel Prize in Physics - NobelPrize.org
The discovery of the binary pulsar Hulse's and Taylor's discovery in 1974 of the first binary pulsar, called PSR 1913 + 16 (PSR stands for pulsar, and 1913 + ...Missing: date B1913+
[180]
[1411.3930] 1974: the discovery of the first binary pulsar - arXiv
Nov 14, 2014 · The 1974 discovery of the first binary pulsar, PSR B1913+16, by Hulse and Taylor, opened new possibilities for studying relativistic gravity.<|separator|>
[181]
Pulsar Gravitational Waves Win Nobel Prize - Cosmic Times - NASA
May 24, 2019 · Hulse and Taylor first observed the pulsar PSR 1913+16 in 1974 while they were searching for pulsars. They soon discovered that it was in a ...Missing: date B1913+
[182]
Tests of general relativity from timing the double pulsar - arXiv
Sep 14, 2006 · Abstract: The double pulsar system, PSR J0737-3039A/B, is unique in that both neutron stars are detectable as radio pulsars.
[183]
Einstein's theory holds up after 16-year test - Cosmos Magazine
Dec 14, 2021 · The two pulsars are predicted to collide in 85 million years' time as, according to general relativity, the extreme accelerations in the system ...
[184]
[1101.2299] SGR 0418+5729: a low-magnetic-field magnetar - arXiv
Jan 12, 2011 · We found evidence for a magnetar with a low magnetic field, SGR 0418+5729, recently detected after it emitted bursts similar to those of soft ...
[185]
THE OUTBURST DECAY OF THE LOW MAGNETIC FIELD ...
This measurement confirms SGR 0418+5729 as the lowest magnetic field magnetar. Following the flux and spectral evolution from the beginning of the outburst up ...
[186]
Modelling of the surface emission of the low magnetic field magnetar ...
We perform a detailed modelling of the post-outburst surface emission of the low magnetic field magnetar SGR 0418+5729. The dipolar magnetic field of this ...
[187]
Discovery and timing of ten new millisecond pulsars in the globular ...
We report the discovery of ten new pulsars in the globular cluster Terzan 5 as part of the Transients and Pulsars with MeerKAT (TRAPUM) Large Survey Project.
[188]
Exploring polarization and geometry in the X-ray pulsar 4U 1538−52
We present the first X-ray polarimetric study of the persistent wind-fed XRP 4U 1538−52, based on five IXPE observations totaling 360 ks, conducted in March ...
[189]
https://phys.org/news/2025-09-jwst-exoplanet-pulsar-atmosphere-carbon.html
[190]
JWST finds an exoplanet around A pulsar whose atmosphere is all ...
Sep 11, 2025 · Sep 8, 2025. Planet K2-18b may not host alien life, but it is home to a water-rich interior. Jul 28, 2025. report. Water and carbon dioxide ...
[191]
Origin of Pulsar Radio Emission | Phys. Rev. Lett.
Since pulsars were discovered as emitters of bright coherent radio emission more than half a century ago, the cause of the emission has remained a mystery.
[192]
[PDF] Origin of pulsar radio emission - Indico
Jul 5, 2022 · For more than five decades, the origin of pulsar coherent radio emission has been one of the major unsolved problems in astrophysics.
[193]
Pulsar glitches from quantum vortex networks | Scientific Reports
Apr 3, 2024 · One of the unsolved long-standing problems of these enigmatic celestial bodies is the origin of pulsars' glitches, i.e., the sudden rapid ...
[194]
Glitches and Glitching Clusters in Rotation-powered Pulsars
Dec 24, 2024 · The exact causes of glitches and the resulting processes, such as their origin and triggering mechanism, are unsolved problems. Whether glitches ...
[195]
What Can We Learn about the Unstable Equation-of-state Branch ...
Feb 1, 2024 · In this work, we explore whether the EOS above n TOV can be measured from gravitational-wave or electromagnetic observations of the postmerger remnant.
[196]
Pulsar timing irregularities and the imprint of magnetic field evolution
We investigate whether changes of the magnetic field structure and strength during the star evolution may have observable consequences in the braking index n.
[197]
Pulsar magnetic alignment and the pulsewidth–age relation
The results are inconsistent with models based on magnetic field decay alone or monotonic counter-alignment to orthogonal rotation. The best fits are obtained ...
[198]
Pair Production near Threshold in Pulsar Magnetic Fields
Since pair production is suppressed near threshold, the photon mean free paths are longer than previously thought. In magnetic fields approximately 6x10 ...Missing: unverified | Show results with:unverified
[199]
Deriving pulsar pair-production multiplicities from pulsar wind ...
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[200]
Pulsars might help identify dark matter, researcher says | News
Aug 27, 2024 · LoSecco is the first to apply pulsar data to the identification of dark matter, discovering 12 signals that appear to be dark matter objects by analyzing the ...Missing: injections | Show results with:injections
[201]
How astronomers are using pulsars to observe evidence of dark matter
Tantalising evidence of potential dark matter objects has been detected with the help of the Universe's 'timekeepers'.Missing: injections | Show results with:injections
[202]
[1501.00056] A Cosmic Census of Radio Pulsars with the SKA - arXiv
Dec 31, 2014 · The Square Kilometre Array (SKA) will make ground breaking discoveries in pulsar science. In this chapter we outline the SKA surveys for new pulsars.Missing: prospects | Show results with:prospects
[203]
The prospects of pulsar timing with new-generation radio telescopes ...
Apr 16, 2018 · The Square Kilometre Array will revolutionize pulsar searches and timing precision. The increased number of sources will reveal rare sources, ...
[204]
[2407.00262] Prospects for the detection of very-high-energy pulsars ...
Jun 28, 2024 · Our results indicate that LHAASO could detect the Crab's pulsed signal within six years, while SWGO might detect Vela's signal within one year.Missing: timeline | Show results with:timeline
[205]
Perspectives for multimessenger astronomy with the next generation ...
Here, we explore the perspectives of ET, as a single observatory and in a network of gravitational-wave (GW) detectors, operating in synergy with future γ-ray ...
[206]
Investigation of a Machine learning methodology for the SKA pulsar ...
Sep 9, 2022 · Here we describe our findings from testing a state of the art object detection algorithm called Mask R-CNN to detect candidate signatures in the SKA pulsar ...
[207]
Finding radio transients with anomaly detection and active learning ...
Feb 25, 2025 · ABSTRACT. In this work, we explore the applicability of unsupervised machine learning algorithms to finding radio transients.