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we present timing solutions for 12 pulsars discovered in the green bank north celestial cap 350 mhz pulsar survey, including six millisecond pulsars (msps), a double neutron star (dns) system, and a pulsar orbiting a massive white dwarf companion. timing solutions presented here include 350 and 820 mhz green bank teles... | the green bank north celestial cap survey. vii. 12 new pulsar timing solutions |
we report the discovery of absorption features in the x-ray spectrum of the transient x-ray pulsar gro j2058+42. the features are detected around ∼10, ∼20, and ∼30 kev in both nustar observations carried out during the source type ii outburst in spring 2019. the most intriguing property is that the deficit of photons a... | discovery of a pulse-phase-transient cyclotron line in the x-ray pulsar gro j2058+42 |
we report the discovery of diffuse x-ray emission around the supernova remnant (snr) g106.3+2.7, which is associated with ver j2227+608 and hawc j2227+610 and is known as a candidate for a pev cosmic-ray accelerator (pevatron). we analyze observational data of suzaku around the snr and the adjacent pulsar psr j2229+611... | x-ray emission from the pevatron-candidate supernova remnant g106.3+2.7 |
recently, the high altitude water cherenkov (hawc) collaboration reported the discovery of a tev halo around the geminga pulsar. the tev emission is believed to originate from the inverse compton scattering of pulsar-injected electrons/positrons off cosmic microwave background photons. during this time, these electrons... | constraining the magnetic field in the tev halo of geminga with x-ray observations |
we investigate the aperiodic variability for a relatively large sample of accreting neutron stars and intermediate polars, focusing on the properties of the characteristic break commonly observed in power spectra of accreting objects. in particular, we investigate the relation of the break frequency and the magnetic fi... | constraints on the magnetic field structure in accreting compact objects from aperiodic variability |
the opening of the gravitational wave window by ground-based laser interferometers has made possible many new tests of gravity, including the first constraints on polarization. it is hoped that, within the next decade, pulsar timing will extend the window by making the first detections in the nanohertz frequency regime... | constraining alternative theories of gravity using pulsar timing arrays |
observations by the high altitude water cherenkov (hawc) observatory indicate that many young pulsars (including geminga and monogem) are surrounded by spatially extended, multi-tev emitting regions. it is not currently known, however, whether tev emission is also produced by recycled, millisecond pulsars (msps). in th... | millisecond pulsars, tev halos, and implications for the galactic center gamma-ray excess |
we study the influence of strong magnetic fields in hybrid stars, composed by hadrons and a pure quark matter core, and analyse their structure and stability as well as some possible evolution channels due to the magnetic field decay. using an ad hoc parametrization of the magnetic field strength and taking into accoun... | magnetized hybrid stars: effects of slow and rapid phase transitions at the quark-hadron interface |
this chapter discusses the implications of x-ray binaries on our knowledge of type ibc and type ii supernovae. x-ray binaries contain accreting neutron stars and stellar-mass black holes which are the end points of massive star evolution. studying these remnants thus provides clues to understanding the evolutionary pro... | x-ray binaries |
in the last 20 years our understanding of the millisecond pulsar population changed dramatically. thanks to the large effective area and good time resolution of the nasa x-ray observatory rossi x-ray timing explorer, we discovered that neutron stars in low mass x-ray binaries (lmxbs) spins at frequencies between 200 an... | accreting pulsars: mixing-up accretion phases in transitional systems |
the fermi large area telescope has provided the most detailed view towards the galactic centre (gc) in high-energy gamma-rays. besides the interstellar emission and point source contributions, the data suggest a residual diffuse gamma-ray excess. the similarity of its spatial distribution with the expected profile of d... | disrupted globular clusters and the gamma-ray excess in the galactic centre |
we report the discovery of psr j2251-3711, a radio pulsar with a spin period of 12.1 s, the second longest currently known. its timing parameters imply a characteristic age of 15 myr, a surface magnetic field of 1.3 × 1013 g, and a spin-down luminosity of 2.9 × 1029 erg s-1. its dispersion measure of 12.12(1) pc cm-3 l... | the survey for pulsars and extragalactic radio bursts - iv. discovery and polarimetry of a 12.1-s radio pulsar |
low-frequency gravitational-wave experiments require the highest timing precision from an array of the most stable millisecond pulsars. several known sources of noise on short timescales in single radio pulsar observations are well described by a simple model of three components: template fitting from a finite signal-t... | the nanograv 12.5 yr data set: the frequency dependence of pulse jitter in precision millisecond pulsars |
we report on a series of spectroscopic observations of psr j1311-3430, an extreme black-widow gamma-ray pulsar with a helium-star companion. in a previous study we estimated the neutron star mass as {{m}ns}=2.68+/- 0.14 {{m}⊙ } (statistical error), based on limited spectroscopy and a basic (direct heating) light-curve ... | a spectroscopic study of the extreme black widow psr j1311-3430 |
black-holes are known to span at least 9 orders of magnitude in mass: from the stellar-mass objects observed by the laser interferometer gravitational-wave observatory scientific collaboration and virgo collaboration, to supermassive black-holes like the one observed by the event horizon telescope at the heart of m87. ... | sensitivity of present and future detectors across the black-hole binary gravitational wave spectrum |
we have conducted the meterwavelength single-pulse polarimetric emission survey to study the radio emission properties of normal pulsars. a total of 123 pulsars with periods between 0.1 and 8.5 s were observed in the survey at two different frequencies: 105 profiles at 333 mhz, 118 profiles at 618 mhz, and 100 pulsars ... | meterwavelength single-pulse polarimetric emission survey |
the detection of a stochastic gravitational-wave signal from the superposition of many inspiraling supermassive black holes with pulsar timing arrays (ptas) is likely to occur within the next decade. with this detection will come the opportunity to learn about the processes that drive black-hole-binary systems toward m... | constraining the solution to the last parsec problem with pulsar timing |
we investigate compact objects formed by dark matter admixed with ordinary matter made of neutron-star matter and white-dwarf material. we consider non-self annihilating dark matter with an equation of state given by an interacting fermi gas. we find new stable solutions, dark compact planets, with earth-like masses an... | dark compact planets |
understanding the average motion of a multitude of superfluid vortices in the interior of a neutron star is a key ingredient for most theories of pulsar glitches. in this paper, we propose a kinetic approach to compute the mutual friction force that is responsible for the momentum exchange between the normal and superf... | superfluid vortex-mediated mutual friction in non-homogeneous neutron star interiors |
in this paper we present a coherent timing analysis of the 401 hz pulsations of the accreting millisecond x-ray pulsar sax j1808.4-3658 during its 2019 outburst. using observations collected with the neutron star interior composition explorer (nicer), we establish the pulsar spin frequency and orbital phase during its ... | timing the pulsations of the accreting millisecond pulsar sax j1808.4-3658 during its 2019 outburst |
we present the spin frequency and profile evolution of the radio pulsar j1119 - 6127 following magnetar-like x-ray bursts from the system in 2016 july. using data from the parkes radio telescope, we observe a smooth and fast spin-down process subsequent to the x-ray bursts resulting in a net change in the pulsar rotati... | peculiar spin frequency and radio profile evolution of psr j1119-6127 following magnetar-like x-ray bursts |
understanding the evolution of the angle χ between a magnetar's rotation and magnetic axes sheds light on the star's birth properties. this evolution is coupled with that of the stellar rotation ω, and depends on the competing effects of internal viscous dissipation and external torques. we study this coupled evolution... | magnetar birth: rotation rates and gravitational-wave emission |
neutron stars are known to show accelerated spin-up of their rotational frequency called a glitch. highly magnetized rotating neutron stars (pulsars) are frequently observed by radio telescopes (and in other frequencies), where the glitch is observed as irregular arrival times of pulses which are otherwise very regular... | prospects for detecting and localizing short-duration transient gravitational waves from glitching neutron stars without electromagnetic counterparts |
we study the redshift-space fluctuations induced by a stochastic gravitational wave background (sgwb) via the sachs-wolfe effect. the redshift-space fluctuations can be encapsulated in a line-of-sight integral that is useful for studying the imprint of short-wavelength gravitational waves on the cosmic microwave backgr... | redshift-space fluctuations in stochastic gravitational wave background |
hawc j1826-128 is one of the brightest galactic tev γ-ray sources detected by the high altitude water cherenkov (hawc) observatory, with photon energies extending up to nearly ~100 tev. this hawc source spatially coincides with the h.e.s.s. tev source hess j1826-130 and the "eel" pulsar wind nebula (pwn), which is asso... | the eel pulsar wind nebula: a pevatron-candidate origin for hawc j1826-128 and hess j1826-130 |
we report four new pulsars discovered in the core-collapsed globular cluster (gc) ngc 6624 by the trapum large survey project with the meerkat telescope. all of the new pulsars found are isolated. psr j1823-3021i and psr j1823-3021k are millisecond pulsars with period of respectively 4.319 and 2.768 ms. psr j1823-3021j... | four pulsar discoveries in ngc 6624 by trapum using meerkat |
we perform three-dimensional (3d) hydrodynamical simulations of new-born neutron stars (nss) colliding with main-sequence binary companions after a supernova explosion. based on those hydrodynamical models, we construct a semi-analytical formula that describes the drag force inside stars with steep density gradients. w... | neutron stars colliding with binary companions: formation of hypervelocity stars, pulsar planets, bumpy superluminous supernovae and thorne-żytkow objects |
pulsar timing offers an independent avenue to test general relativity and alternative gravity theories. this requires an understanding of how metric polarizations beyond the familiar transverse tensor ones imprint as a stochastic gravitational wave background and correlate the arrival time of radio pulses from a pair o... | stochastic gravitational wave background phenomenology in a pulsar timing array |
we report results on the timing analysis of the 2020 giant outburst of 1a 0535+262, using broadband data from insight-hxmt. the analysis of the pulse profile evolution from the subcritical-luminosity to the supercritical-luminosity regime is presented for the first time. we found that the observed pulse profile exhibit... | timing properties of the x-ray accreting pulsar 1a 0535+262 studied with insight-hxmt |
we present 22 new (+3 confirmed) cataclysmic variables (cvs) in the non-core-collapsed globular cluster 47 tucanae (47 tuc). the total number of cvs in the cluster is now 43, the largest sample in any globular cluster so far. for the identifications we used near-ultraviolet (nuv) and optical images from the hubble spac... | new cataclysmic variables and other exotic binaries in the globular cluster 47 tucanae* |
we present results from observations of the galactic center magnetar, psr j1745-2900, at 2.3 and 8.4 ghz with the nasa deep space network 70 m antenna, dss-43. we study the magnetar’s radio profile shape, flux density, radio spectrum, and single pulse behavior over a ∼1 year period between mjds 57233 and 57621. in part... | pulse morphology of the galactic center magnetar psr j1745-2900 |
searching for gravitational waves in pulsar timing array data is computationally intensive. the data is unevenly sampled, and the noise is heteroscedastic, necessitating the use of a time-domain likelihood function with attendant expensive matrix operations. the computational cost is exacerbated when searching for indi... | fast bayesian analysis of individual binaries in pulsar timing array data |
many short gamma-ray bursts (grbs) originate from binary neutron star mergers, and there are several theories that predict the production of coherent, prompt radio signals either prior, during, or shortly following the merger, as well as persistent pulsar-like emission from the spin-down of a magnetar remnant. here we ... | early-time searches for coherent radio emission from short grbs with the murchison widefield array |
we describe the design of a gravitational wave timing array, a novel scheme that can be used to search for low-frequency gravitational waves by monitoring continuous gravitational waves at higher frequencies. we show that observations of gravitational waves produced by galactic binaries using a space-based detector lik... | gravitational wave timing array |
the state of supranuclear matter in compact stars remains puzzling, and it is argued that pulsars could be strangeon stars. what would happen if binary strangeon stars merge? this kind of merger could result in the formation of a hyper-massive strangeon star, accompanied by bursts of gravitational waves and electromagn... | merging strangeon stars |
in this work we introduce a novel approach to the pulsar classification problem in time-domain radio astronomy using a born machine, often referred to as a quantum neural network. using a single-qubit architecture, we show that the pulsar classification problem maps well to the bloch sphere and that comparable accuraci... | quantum machine learning for radio astronomy |
globular clusters (gcs) are the ideal environment for the formation of neutron stars (nss) and millisecond pulsars (msps). nss origin and evolution provide a useful information on stellar dynamics and evolution in star clusters. nss are among the most interesting astrophysical objects, being precursors of several high-... | neutron stars and millisecond pulsars in star clusters: implications for the diffuse gamma-radiation from the galactic centre |
the repeating frb 121102, the only fast radio burst (frb) with an accurately determined position, is associated with a variable persistent radio source. i suggest that an frb originates in the accretion disc funnels of black holes. narrowly collimated radiation is emitted along the wandering instantaneous angular momen... | frb as products of accretion disc funnels |
we consider the acceleration of leptons up to gev-tev energies in the bow shock wind nebula of psr j0437-4715 and their subsequent diffusion through the interstellar magnetic fields. the leptons accelerated at the pulsar wind termination surface are injected into re-acceleration in colliding shock flows. modeled spectr... | gev-tev cosmic-ray leptons in the solar system from the bow shock wind nebula of the nearest millisecond pulsar j0437-4715 |
force-free electrodynamics (ffe) is a closed set of equations for the electromagnetic field of a magnetically dominated plasma. there are strong arguments for the existence of force-free plasmas near pulsars and active black holes, but ffe alone cannot account for the observational signatures, such as coherent radio em... | effective field theory of force-free electrodynamics |
in this paper, we estimate the sensitivity of gravitational wave (gw) detection for future chinese pulsar timing array (pta) projects. the calculation of sensitivity is based on the well-known crámer-rao bound idea. the red noise and dispersion measure (dm) variation noise has be included in the modeling. we demonstrat... | prospects of gravitational wave detection using pulsar timing array for chinese future telescopes |
neutron stars are fascinating astrophysical objects immersed in strong gravitational and electromagnetic fields, at the edge of our current theories. these stars manifest themselves mostly as pulsars, emitting a timely very stable and regular electromagnetic signal. even though discovered almost fifty years ago, they s... | theory of pulsar magnetosphere and wind |
a detailed analysis of nulling was conducted for the pulsars studied in the meterwavelength single-pulse polarimetric emission survey. we characterized nulling in 36 pulsars including 17 pulsars where the phenomenon was reported for the first time. the most dominant nulls lasted for a short duration, less than five per... | meterwavelength single-pulse polarimetric emission survey. iii. the phenomenon of nulling in pulsars |
we investigate the possible scenario of deconfinement of hyperon rich hadronic matter to quark matter at high densities and the resulting hybrid star (hs) properties are analyzed. in the relativistic mean-field framework, we construct the equation of state (eos) of hadronic matter using the effective chiral model while... | effects of hadron-quark phase transition on properties of neutron stars |
the temporal stability of millisecond pulsars is remarkable, rivaling even some terrestrial atomic clocks at long timescales. using this property, we show that millisecond pulsars distributed in the galactic neighborhood form an ensemble of accelerometers from which we can directly extract the local galactic accelerati... | milky way accelerometry via millisecond pulsar timing |
in this paper, we consider the mimetic gravitational theory to derive a novel category of anisotropic star models. to end and to put the resulting differential equations into a closed system, the form of the metric potential grr as used by tolman is assumed, as well as a linear form of the equation of state. the result... | anisotropic compact stars in the mimetic gravitational theory |
here we present stringent low-frequency (185 mhz) limits on coherent radio emission associated with a short-duration gamma-ray burst (sgrb). our observations of the short gamma-ray burst (grb) 180805a were taken with the upgraded murchison widefield array (mwa) rapid-response system, which triggered within 20s of recei... | murchison widefield array rapid-response observations of the short grb 180805a |
context. accreting highly magnetized pulsars in binary systems are among the brightest x-ray emitters in our galaxy. although a number of high-quality broad-band (0.1-100 kev) x-ray observations are available, the spectral energy distribution of these sources is usually investigated by adopting pure phenomenological mo... | a new model for the x-ray continuum of the magnetized accreting pulsars |
the recent discovery of a population of eccentric (e ∼ 0.1) millisecond pulsar (msp) binaries with low-mass white dwarf companions in the galactic field represents a challenge to evolutionary models that explain msp formation as recycling: all such models predict that the orbits become highly circularized during a long... | a massive millisecond pulsar in an eccentric binary |
we report on timing, flux density, and polarimetric observations of the transient magnetar and 5.54 s radio pulsar xte j1810-197 using the green bank, nançay, and parkes radio telescopes beginning in early 2006, until its sudden disappearance as a radio source in late 2008. repeated observations through 2016 have not d... | radio disappearance of the magnetar xte j1810-197 and continued x-ray timing |
faraday rotation occurs along every line of sight in the galaxy; rotation measure (rm) synthesis allows a 3d representation of the interstellar magnetic field. this study uses data from the global magneto-ionic medium survey, a combination of single-antenna spectro-polarimetric studies, including northern sky data from... | the galactic magneto-ionic medium survey: moments of the faraday spectra |
we describe psr j1926-0652, a pulsar recently discovered with the five-hundred-meter aperture spherical radio telescope (fast). using sensitive single-pulse detections from fast and long-term timing observations from the parkes 64 m radio telescope, we probed phenomena on both long and short timescales. the fast observ... | psr j1926-0652: a pulsar with interesting emission properties discovered at fast |
perpendicular relativistic (γ0= 10) shocks in magnetized pair plasmas are investigated using two-dimensional particle-in-cell simulations. a systematic survey, from unmagnetized to strongly magnetized shocks, is presented accurately capturing the transition from weibel-mediated to magnetic-reflection-shaped shocks. thi... | perpendicular relativistic shocks in magnetized pair plasma |
accreting pulsars power relativistic jets and display a complex spin phenomenology. these behaviours may be closely related to the large-scale configuration of the star's magnetic field, shaped by its interaction with the surrounding accretion disc. here, we present the first relativistic simulations of the interaction... | simulations of the magnetospheres of accreting millisecond pulsars |
the detection of the unusually heavy binary neutron star merger gw190425 marked a stark contrast to the mass distribution from known galactic pulsars in double neutron star binaries and gravitational-wave source gw170817. we suggest here a formation channel for heavy binary neutron stars and light black hole-neutron st... | fallback supernova assembly of heavy binary neutron stars and light black hole-neutron star pairs and the common stellar ancestry of gw190425 and gw200115 |
psr j1829+2456 is a radio pulsar in a relativistic binary system with another neutron star. it has a rotational period of 41 ms and a mildly eccentric (e = 0.14) 28 h orbit. we have continued its observations with the arecibo radio telescope and have now measured the individual neutron star masses of this system: the p... | precise mass measurements for the double neutron star system j1829+2456 |
pulsars in the galactic centre promise to enable unparalleled tests of gravity theories and black hole physics and to serve as probes of the stellar formation history and evolution and the interstellar medium in the complex central region of the milky way. the community has surveyed the innermost region of the galaxy f... | searching for pulsars in the galactic centre at 3 and 2 mm |
context. during its performance verification phase, the soft x-ray instrument erosita on board the spektrum-roentgen-gamma (srg) spacecraft observed large regions in the magellanic clouds in which almost 40 known high-mass x-ray binaries (hmxbs, including candidates) are located.aims: we looked for new hmxbs in the ero... | erosita calibration and performance verification phase: high-mass x-ray binaries in the magellanic clouds |
subpulse drifting in pulsar radio emission is considered to be one of the most promising phenomena for uncovering the underlying physical processes. here, we present a detailed study of such a phenomenon in observations of psr j1822-2256, made using the upgraded giant meterwave radio telescope (ugmrt). observations wer... | revisiting the subpulse drifting phenomenon in psr j1822-2256: drift modes, sparks, and emission heights |
we study the observation of polarized stochastic gravitational-wave background (sgwb) in pulsar-timing-array experiments. the time residual for an observed pulsar is formulated as a line-of-sight integral that incorporates the effects of the pulsar term, from which we construct the correlation function of the time resi... | observation of a polarized stochastic gravitational-wave background in pulsar-timing-array experiments |
we report the discovery of psr j1555-2908, a 1.79 ms radio and gamma-ray pulsar in a 5.6 hr binary system with a minimum companion mass of 0.052 m ⊙. this fast and energetic ( $\dot{e}=3\times {10}^{35}$ erg s-1) millisecond pulsar was first detected as a gamma-ray point source in fermi large area telescope (lat) sky s... | discovery, timing, and multiwavelength observations of the black widow millisecond pulsar psr j1555-2908 |
we investigate the anisotropies of the stochastic gravitational-wave background (sgwb) produced by cosmic strings associated with the spontaneous u(1) symmetry breaking of grand unified theory, which happens at the onset of inflation. the string network evolution is determined by primordial fluctuations and never reach... | a new picture of cosmic string evolution and anisotropic stochastic gravitational-wave background |
the curvature radiation is applied to the explanation of the circular polarization of fast radio bursts (frbs). significant circular polarization is reported in both apparently non-repeating and repeating frbs. curvature radiation can produce significant circular polarization at the wing of the radiation beam. in the c... | circular polarization of fast radio bursts in the curvature radiation scenario |
in this paper, we introduce the post-minkowskian approximation of energy-momentum-squared gravity (emsg). this approximation is used to study the gravitational energy flux in the context of emsg. as an application of our results, we investigate the emsg effect on the first time derivative of the orbital period of the b... | constraining energy-momentum-squared gravity by binary pulsar observations |
we present a global kinetic plasma simulation of an axisymmetric pulsar magnetosphere with self-consistent e ± pair production. we use the particle-in-cell method and log-spherical coordinates with a grid size 4096 × 4096. this allows us to achieve a high voltage induced by the pulsar rotation and investigate pair crea... | axisymmetric pulsar magnetosphere revisited |
fermi science tools is a suite of tools for the analysis of both the large-area telescope (lat) and the gamma-ray burst monitor (gbm) data, including point source analysis for generating maps, spectra, and light curves, pulsar timing analysis, and source identification. | fermitools: fermi science tools |
context. as the importance of gravitational wave (gw) astrophysics increases rapidly, astronomers interested in gws who are not experts in this field sometimes need to get a quick idea of what gw sources can be detected by certain detectors, and the accuracy of the measured parameters.aims: the gw-toolbox is a set of e... | the gravitational wave universe toolbox. a software package to simulate observations of the gravitational wave universe with different detectors |
several conjectures have been put forward to explain rotating radio transients (rrats), the newest subclass of neutron stars, and their connections to other radio pulsars. this work discusses these conjectures in the context of the characteristic properties of the rrat population. contrary to expectations, it is seen t... | radio pulsar sub-populations (ii): the mysterious rrats |
anaeromyxobacter is globally distributed in soil environments, especially predominant in paddy soils. current studies based on environmental dna/rna analyses frequently detect gene fragments encoding nitrogenase of anaeromyxobacter from various soil environments. although the importance of anaeromyxobacter as a diazotr... | diazotrophic anaeromyxobacter isolates from soils |
we investigate the properties of asymmetric quark matter and strange quark matter in the framework of the su(3) nambu-jona-lasinio (njl) model with two types of vector interactions: (1) the flavor-dependent repulsion among different flavors of quarks with the coupling constant gv , and (2) the universal repulsion and t... | quark matter in an su(3) nambu-jona-lasinio model with two types of vector interactions |
it has been recently claimed by two different groups that the spectral modulation observed in gamma rays from galactic pulsars and supernova remnants can be due to conversion of photons into ultra-light axion-like-particles (alps) in large-scale galactic magnetic fields. while we show the required best-fit photon-alp c... | reconciling hints on axion-like-particles from high-energy gamma rays with stellar bounds |
black widows are close binary systems in which a millisecond pulsar is orbited by a companion, a few per cent the mass of the sun. it has been suggested that the pulsar's rotationally powered γ-ray luminosity gradually evaporates the companion, eventually leaving behind an isolated millisecond pulsar. the evaporation e... | black widow evolution: magnetic braking by an ablated wind |
dm_phase maximizes the coherent power of a radio signal instead of its intensity to calculate the best dispersion measure (dm) for a burst such as those emitted by pulsars and fast radio bursts (frbs). it is robust to complex burst structures and interference, thus mitigating the limitations of traditional methods that... | dm_phase: algorithm for correcting dispersion of radio signals |
with the largest dish five-hundred-meter aperture spherical radio telescope (fast), both the mean and single pulses of psr b2016+28, especially including the single-pulse structure, are investigated in detail in this study. the mean pulse profiles at different frequencies can be well fitted in a conal model, and the pe... | the radiation structure of psr b2016+28 observed with fast |
we report on the results of a 4 year timing campaign of psr j2222-0137, a 2.44 day binary pulsar with a massive white dwarf (wd) companion, with the nançay, effelsberg, and lovell radio telescopes. using the shapiro delay for this system, we find a pulsar mass mp= 1.76 ± 0.06 m ⊙ and a wd mass mc= 1.293 ± 0.025 m ⊙. we... | a massive-born neutron star with a massive white dwarf companion |
repeating and apparently non-repeating fast radio bursts (frbs) differ by orders of magnitude in duty factors, energy, and rotation measure. extensive monitoring of apparently non-repeating frb has failed to find any repetitions. this suggests that the two types differ qualitatively, rather than in repetition rate, and... | fast radio burst energetics and sources |
we perform 2.5d axisymmetric simulations of the pulsar magnetosphere (aligned dipole rotator) using the charge conservative, relativistic, electromagnetic particle in cell code picsar. particle in cell codes are a powerful tool to use for studying the pulsar magnetosphere, because they can handle the force-free and vac... | dissipation, energy transfer, and spin-down luminosity in 2.5d pic simulations of the pulsar magnetosphere |
the paucity of observed supermassive black hole binaries (smbhbs) may imply that the gravitational wave background (gwb) from this population is anisotropic, rendering existing analyses suboptimal. we present the first constraints on the angular distribution of a nanohertz stochastic gwb from circular, inspiral-driven ... | limits on anisotropy in the nanohertz stochastic gravitational wave background |
we present the first sub-arcminute images of the galactic center above 10 kev, obtained with nustar. nustar resolves the hard x-ray source igr j17456-2901 into non-thermal x-ray filaments, molecular clouds, point sources, and a previously unknown central component of hard x-ray emission (chxe). nustar detects four non-... | nustar hard x-ray survey of the galactic center region i: hard x-ray morphology and spectroscopy of the diffuse emission |
> we review our high-time-resolution radio observations of the crab pulsar and compare our data to a variety of models for the emission physics. the main pulse and the low frequency interpulse come from regions somewhere in the high-altitude emission zones (caustics) that also produce pulsed x-ray and -ray emission.... | radio emission physics in the crab pulsar |
relic gravitational waves (rgws) generated in the early universe form a stochastic gw background, which can be directly probed by measuring the timing residuals of millisecond pulsars. in this paper, we investigate the constraints on the rgws and on the inflationary parameters by the observations of current and potenti... | detecting relic gravitational waves by pulsar timing arrays: effects of cosmic phase transitions and relativistic free-streaming gases |
we report the discovery of two long-term intermittent radio pulsars in the ongoing pulsar arecibo l-band feed array survey. following discovery with the arecibo telescope, extended observations of these pulsars over several years at jodrell bank observatory have revealed the details of their rotation and radiation prop... | two long-term intermittent pulsars discovered in the palfa survey |
we combined chandra acis observations of the globular cluster 47 tucanae (47 tuc) from 2000, 2002 and 2014-2015 to create a deeper x-ray source list, and study some of the faint radio millisecond pulsars (msps) present in this cluster. we have detected 370 x-ray sources within the half-mass radius (2.79 arcsec) of the ... | chandra studies of the globular cluster 47 tucanae: a deeper x-ray source catalogue, five new x-ray counterparts to millisecond radio pulsars, and new constraints to r-mode instability window |
braking index measurements of young radio pulsars are all smaller than the value expected for spin-down by magnetic dipole braking. we investigate magnetic field evolution in the neutron star crust due to hall drift as an explanation for observed braking indices. using numerical simulations and a semi-analytic model, w... | hall drift and the braking indices of young pulsars |
an exact solution of two singularities in the teleparallel equivalent to general relativity theory has been obtained. a holographic visualization of the binary black holes (bbhs) space-time, due to the non vanishing torsion scalar field, has been given. the acceleration tensor of bbhs space-time has been calculated. th... | exact teleparallel gravity of binary black holes |
we have discovered 21 rotating radio transients (rrats) in data from the green bank telescope (gbt) 350 mhz drift-scan and the green bank north celestial cap pulsar surveys using a new candidate sifting algorithm. rrats are pulsars with sporadic emission that are detected through their bright single pulses rather than ... | discovery and follow-up of rotating radio transients with the green bank and lofar telescopes |
due to observational challenges, our knowledge of low-level accretion flows around neutron stars is limited. we present nustar, swift and chandra observations of the low-mass x-ray binary igr j17062-6143, which has been persistently accreting at ≃0.1 per cent of the eddington limit since 2006. our simultaneous nustar/s... | an in-depth study of a neutron star accreting at low eddington rate: on the possibility of a truncated disc and an outflow |
we present a comprehensive discussion about the origin of the features in the leptonic component of the cosmic-ray spectrum. working in the framework of a up-to-date cr transport scenario tuned on the most recent ams-02 and voyager data, we show that the prominent features recently found in the positron and in the all-... | features in cosmic-ray lepton data unveil the properties of nearby cosmic accelerators |
the dark matter particle explorer (dampe) is a satellite-borne, high-energy particle and -ray detector, which is dedicated to indirectly detecting particle dark matter and studying high-energy astrophysics. the first results about precise measurement of the cosmic ray electron plus positron spectrum between 25 gev and ... | dark matter particle explorer observations of high-energy cosmic ray electrons plus positrons and their physical implications |
we search for far-infrared counterparts of known supernova remnants (snrs) in the galactic plane (10° < |l| < 60°) at 70-500 μm using the herschel infrared galactic plane survey (hi-gal). of 71 sources studied, we find that 29 (41 per cent) snrs have a clear fir detection of dust emission associated with the snr.... | a catalogue of galactic supernova remnants in the far-infrared: revealing ejecta dust in pulsar wind nebulae |
during the spin-up phase of a large pulsar glitch - a sudden decrease of the rotational period of a neutron star - the angular velocity of the star may overshoot, namely reach values greater than that observed for the new post-glitch equilibrium. these transient phenomena are expected on the basis of theoretical models... | core and crust contributions in overshooting glitches: the vela pulsar 2016 glitch |
due to their high magnetic fields and plasma densities, pulsars provide excellent laboratories for tests of beyond standard model (bsm) physics. when axions or axion-like particles (alps) approach closely enough to pulsars, they can be resonantly converted to photons, yielding dramatic electromagnetic signals. we discu... | resonant conversion of dark matter oscillons in pulsar magnetospheres |
cyclotron resonance scattering features observed in the spectra of some x-ray pulsars show significant changes of the line centroid energy with the pulsar luminosity. whereas for bright sources above the so-called critical luminosity, these variations are established to be connected with the appearance of the high-accr... | positive correlation between the cyclotron line energy and luminosity in sub-critical x-ray pulsars: doppler effect in the accretion channel |
we present a new class of solutions to the einstein's field equations corresponding to a static spherically symmetric anisotropic system by generalizing the ansatz of finch and skea [class. quantum grav. 6:467, 1989] for the gravitational potential grr . the anisotropic stellar model previously studied by sharma and ra... | modified finch and skea stellar model compatible with observational data |
it is difficult to discover pulsars via their gamma-ray emission because current instruments typically detect fewer than one photon per million rotations. this creates a significant computing challenge for isolated pulsars, where the typical parameter search space spans wide ranges in four dimensions. it is even more d... | exploiting orbital constraints from optical data to detect binary gamma-ray pulsars |
we model millisecond pulsar winds colliding with radiatively driven companion winds in black widow and redback systems. for the redbacks, the geometry of this intrabinary shock (ibs) is quite sensitive to the expected equatorial concentration in the pulsar outflow. we thus analytically extend ibs thin-shock models to ∼... | the synchrotron emission pattern of intrabinary shocks |
motivated by the neutron lifetime puzzle, it is proposed that neutrons may decay into new states yet to be observed. we review the neutron star constraints on dark fermions carrying unit baryon number with masses around 939 mev, and discuss the interaction strengths required for the new particle. the possibility of neu... | neutron star constraints on neutron dark decays |
the exploration of the lunar south polar region and the ground truthing of polar volatiles is one of the top priorities for several space agencies and private partners. here we use moon mineralogy mapper surficial water ice detections to investigate the location of water-ice-bearing permanently shaded regions (psrs) ne... | framework for coordinated efforts in the exploration of volatiles in the south polar region of the moon |
we discuss the unique spin evolution of the young x-ray pulsar psr j0537-6910, a system in which the regular spin down is interrupted by glitches every few months. drawing on the complete timing data from the rossi x-ray timing explorer (from 1999 to 2011), we argue that a trend in the interglitch behavior points to an... | the enigmatic spin evolution of psr j0537-6910: r-modes, gravitational waves, and the case for continued timing |
context. globular clusters (gcs) contain a unique pulsar population, with many exotic systems that can form only in their dense stellar environments. such systems are potentially very interesting for new tests of gravity theories and neutron-star mass measurements.aims: the leap in sensitivity of the upgraded giant met... | upgraded gmrt survey for pulsars in globular clusters. i. discovery of a millisecond binary pulsar in ngc 6652 |
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