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nonlinear oscillatory and monotonic electron acoustic shock waves in dissipative magnetorotating electron-positron-ion plasmas containing cold dynamical electrons, superthermal electrons, and positrons have been analyzed in the stationary background of massive positive ions. the korteweg de-vries-burgers equation which... | effect of anisotropic pressure on electron acoustic oscillatory and monotonic shocks in superthermal magnetoplasma |
we measure the proper motion of the pulsar psr j1745-2900 relative to the galactic center massive black hole, sgr a*, using the very long baseline array (vlba). the pulsar has a transverse velocity of 236 ± 11 km s-1 at position angle 22 ± 2 deg east of north at a projected separation of 0.097 pc from sgr a*. given the... | the proper motion of the galactic center pulsar relative to sagittarius a* |
we analysed in a systematic way the public integral observations spanning from december 2002 to september 2016, to investigate the hard x-ray properties of about 60 high mass x-ray binaries (hmxbs). we considered both persistent and transient sources, hosting either a be star (be/xrbs) or a blue supergiant companion (s... | an integral overview of high-mass x-ray binaries: classes or transitions? |
continuous gravitational waves from neutron stars could provide an invaluable resource to learn about their interior physics. a common search method involves matched filtering a modeled template against the noisy gravitational-wave data to find signals. this method suffers a mismatch (i.e., relative loss of the signal-... | statistical characterization of pulsar glitches and their potential impact on searches for continuous gravitational waves |
neutron stars are the densest objects in the universe, with m ~ 1.4 msolar and r ~ 12 km, and the equation of state associated to their internal composition is still unknown. the extreme conditions to which matter is subjected inside neutron stars could lead to a phase transition in their inner cores, giving rise to a ... | hybrid stars with sequential phase transitions: the emergence of the g2 mode |
in this work, we consider the regret minimization problem for reinforcement learning in latent markov decision processes (lmdp). in an lmdp, an mdp is randomly drawn from a set of $m$ possible mdps at the beginning of the interaction, but the identity of the chosen mdp is not revealed to the agent. we first show that a... | rl for latent mdps: regret guarantees and a lower bound |
for the past couple of decades, the parkes radio telescope has been regularly observing the millisecond pulsars in 47 tucanae (47 tuc). this long-term timing programme was designed to address a wide range of scientific issues related to these pulsars and the globular cluster where they are located. in this paper, the f... | long-term observations of the pulsars in 47 tucanae - i. a study of four elusive binary systems |
we present broadband (3-78 kev) nustar x-ray imaging and spectroscopy of the crab nebula and pulsar. we show that while the phase-averaged and spatially integrated nebula + pulsar spectrum is a power law in this energy band, spatially resolved spectroscopy of the nebula finds a break at ~9 kev in the spectral photon in... | broadband x-ray imaging and spectroscopy of the crab nebula and pulsar with nustar |
we present initial results from the low-latitude galactic plane region of the high time resolution universe pulsar survey conducted at the parkes 64-m radio telescope. we discuss the computational challenges arising from the processing of the terabyte-sized survey data. two new radio interference mitigation techniques ... | the high time resolution universe pulsar survey - xii. galactic plane acceleration search and the discovery of 60 pulsars |
multiwavelength follow-up of unidentified fermi sources has vastly expanded the number of known galactic-field “black widow” and “redback” millisecond pulsar binaries. focusing on their rotation-powered state, we interpret the radio to x-ray phenomenology in a consistent framework. we advocate the existence of two dist... | constraining relativistic bow shock properties in rotation-powered millisecond pulsar binaries |
pulsars are rotating neutron stars that emit periodic electromagnetic radiation. while pulsars generally slow down as they lose energy, some also experience glitches: spontaneous increases of their rotational frequency. according to several models, these glitches can also lead to the emission of long-duration transient... | prospects for detecting transient quasi-monochromatic gravitational waves from glitching pulsars with current and future detectors |
the possibility of neutron-mirror neutron transition has recently been discussed both from theoretical and experimental perspectives. we point out that such a transition would imply mass loss in neutron stars leading to a significant change of the orbital period of neutron star binary systems. known limits on the perio... | bounds on neutron-mirror neutron mixing from pulsar timing |
recently, two photons from the crab nebula with energy of approximately 1 pev were detected by the large high altitude air shower observatory (lhaaso), opening an ultrahigh-energy window for studying pulsar wind nebulae (pwne). remarkably, the lhaaso spectrum at the highest-energy end shows a possible hardening, which ... | pev emission of the crab nebula: constraints on the proton content in pulsar wind and implications |
we investigate the effect of feeble interaction of dark matter (dm) with hadronic matter on the equation of state (eos) and structural properties of neutron stars (nss) in static conditions. for the purpose, we adopt the effective chiral model for the hadronic sector and for the first time in the context of possible ex... | implications of feebly interacting dark sector on neutron star properties and constraints from gw170817 |
we study the impact of a binary companion on black hole superradiance at orbital frequencies away from the resonance bands of the superradiant cloud. a superradiant state can couple to a strongly absorptive state via the tidal perturbation of the companion, thereby acquiring a suppressed superradiance rate. below a cri... | termination of superradiance from a binary companion |
we present measurements of the polarization of x-rays in the 2-8 kev band from the pulsar in the ultracompact low-mass x-ray binary 4u 1626-67 using data from the imaging x-ray polarimetry explorer (ixpe). the 7.66 s pulsations were clearly detected throughout the ixpe observations as well as in the nicer soft x-ray ob... | observations of 4u 1626-67 with the imaging x-ray polarimetry explorer |
context. several new ultrahigh-energy (uhe) γ-ray sources have recently been discovered by the large high altitude air shower observatory (lhaaso) collaboration. these represent a step forward in the search for the so-called galactic pevatrons, the enigmatic sources of the galactic cosmic rays up to pev energies. howev... | multiwavelength study of the galactic pevatron candidate lhaaso j2108+5157 |
superresolution (sr) optical microscopy has allowed the investigation of many biological structures below the diffraction limit; however, most of the techniques are hampered by the need for fluorescent labels. nonlinear label-free techniques such as second-harmonic generation (shg) provide structurally specific contras... | superresolved polarization-enhanced second-harmonic generation for direct imaging of nanoscale changes in collagen architecture |
in this article we put forward a novel phenomenological paradigm in which particle physics beyond the standard model may be tested by radio astronomy if these are related to a first order phase transition in the early universe. for this type of dark matter models, the first order phase transition takes place at kev sca... | testing dark matter models with radio telescopes in light of gravitational wave astronomy |
in this paper, we propose a new scenario in which a rapidly rotating strongly magnetized pulsar without any surrounding supernova ejecta repeatedly produces fast radio bursts (frbs) via a range of possible mechanisms; simultaneously, an ultra-relativistic electron/positron pair wind from the pulsar sweeps up its ambien... | radio emission from pulsar wind nebulae without surrounding supernova ejecta: application to frb 121102 |
we report the measurement of the acoustic quality factor of a gram-scale, kilohertz-frequency superfluid resonator, detected through the parametric coupling to a superconducting niobium microwave cavity. for temperatures between 400 mk and 50 mk, we observe a t^{-4} temperature dependence of the quality factor, consist... | ultra-high q acoustic resonance in superfluid ^4he |
nanosecond plasmas in liquids play an important role in the field of decontamination, electrolysis or plasma medicine. the understanding of these very dynamic plasmas requires information about the temporal variation of species densities and temperatures. this is analyzed by monitoring nanosecond pulsed plasmas that ar... | nanosecond plasmas in water: ignition, cavitation and plasma parameters |
the hawc collaboration has recently reported the detection of bright and spatially extended multi-tev gamma-ray emission from geminga, monogem, and a handful of other nearby, middle-aged pulsars. the angular profile of the emission observed from these pulsars is surprising, in that it implies that cosmic-ray diffusion ... | measuring the local diffusion coefficient with h.e.s.s. observations of very high-energy electrons |
pulsed emission from almost one hundred millisecond pulsars (msps) has been detected in γ-rays by the fermi large-area telescope. the global properties of this population remain relatively unconstrained despite many attempts to model their spatial and luminosity distributions. we perform here a self-consistent bayesian... | bayesian model comparison and analysis of the galactic disc population of gamma-ray millisecond pulsars |
we report on a high-precision timing analysis and an astrophysical study of the binary millisecond pulsar, psr j1909-3744, motivated by the accumulation of data with well improved quality over the past decade. using 15 yr of observations with the nançay radio telescope, we achieve a timing precision of approximately 10... | a revisit of psr j1909-3744 with 15-yr high-precision timing |
psr j1640+2224 is a binary millisecond pulsar (bmsp) with a white dwarf (wd) companion. recent observations indicate that the wd is very likely to be a ∼0.7 m⊙ co wd. thus, the bmsp should have evolved from an intermediate-mass x-ray binary (imxb). however, previous investigations on imxb evolution predict that the orb... | on the formation of psr j1640+2224: a neutron star born massive? |
we report results of the first search to date for continuous gravitational waves from unstable r-modes from the pulsar $\mathrm{psr}\ {\rm{j}}0537\mbox{--}6910$ . we use data from the first two observing runs of the advanced ligo network. we find no significant signal candidate and set upper limits on the amplitude of ... | first search for r-mode gravitational waves from psr j0537-6910 |
a rotating fluid star, endowed with a magnetic field, can undergo a form of precessional motion: a sum of rigid-body free precession and a non-rigid response. on secular time-scales this motion is dissipated by bulk and shear viscous processes in the stellar interior and magnetospheric braking in the exterior, changing... | neutron-star spindown and magnetic inclination-angle evolution |
we report on the results of the extensive multi-wavelength campaign from optical to gev γ-rays of the 2014 periastron passage of psr b1259-63, which is a unique high-mass γ-ray emitting binary system with a young pulsar companion. observations demonstrate the stable nature of the post-periastron gev flare and prove the... | multi-wavelength observations of the binary system psr b1259-63/ls 2883 around the 2014 periastron passage |
we perform a detailed quantitative analysis of the recent ams-02 electron and positron data. we investigate the interplay between the emission from primary astrophysical sources, namely supernova remnants and pulsar wind nebulae, and the contribution from a dark matter annihilation or decay signal. our aim is to assess... | dark matter vs. astrophysics in the interpretation of ams-02 electron and positron data |
the galactic centre hosts a puzzling stellar population in its inner few parsecs, with a high abundance of surprisingly young, relatively massive stars bound within the deep potential well of the central supermassive black hole, sagittarius a* (ref. 1). previous studies suggest that the population of objects emitting s... | extended hard-x-ray emission in the inner few parsecs of the galaxy |
we construct time-dependent one-dimensional (vertically averaged) models of accretion discs produced by the tidal disruption of a white dwarf (wd) by a binary neutron star (ns) companion. nuclear reactions in the disc mid-plane burn the wd matter to increasingly heavier elements at sequentially smaller radii, releasing... | time-dependent models of accretion discs with nuclear burning following the tidal disruption of a white dwarf by a neutron star |
the radiation from accreting x-ray pulsars was expected to be highly polarized, with some estimates for the polarization degree of up to 80%. however, phase-resolved and energy-resolved polarimetry of x-ray pulsars is required in order to test different models and to shed light on the emission processes and the geometr... | ixpe observations of the quintessential wind-accreting x-ray pulsar vela x-1 |
during their most recent observing run, ligo/virgo reported the gravitational wave (gw) transient s191110af, a burst signal at a frequency of 1.78 khz that lasted for 0.104 s. while this signal was later deemed nonastrophysical, genuine detections of uncertain origin will occur in the future. here we study the potentia... | gravitational waves from transient neutron star f -mode oscillations |
an intermediate-mass black hole (imbh) was recently reported to reside in the centre of the galactic globular cluster (gc) ngc 6624, based on timing observations of a millisecond pulsar (msp) located near the cluster centre in projection. we present dynamical models with multiple mass components of ngc 6624 - without a... | mass models of ngc 6624 without an intermediate-mass black hole |
the soft gamma-ray repeater candidate sgr 0755−2933 was discovered in 2016 by swift/bat, which detected a short (∼30 ms), powerful burst typical of magnetars. to understand the nature of the source, we present here an analysis of follow-up observations of the tentative soft-x-ray counterpart of the source obtained with... | sgr 0755−2933: a new high-mass x-ray binary with the wrong name |
we report the discovery of a highly polarized, highly variable, steep-spectrum radio source, askap j173608.2-321635, located ~4° from the galactic center in the galactic plane. the source was detected six times between 2020 january and 2020 september as part of the australian square kilometre array pathfinder variables... | discovery of askap j173608.2-321635 as a highly polarized transient point source with the australian ska pathfinder |
radio-loud magnetars display a wide variety of radio-pulse phenomenology seldom seen among the population of rotation-powered pulsars. spectropolarimetry of the radio pulses from these objects has the potential to place constraints on their magnetic topology and unveil clues about the magnetar radio emission mechanism.... | the dynamic magnetosphere of swift j1818.0-1607 |
we report the follow-up of 10 pulsars discovered by the five-hundred-metre aperture spherical radio-telescope (fast) during its commissioning. the pulsars were discovered at a frequency of 500-mhz using the ultrawide-band (uwb) receiver in drift-scan mode, as part of the commensal radio astronomy fast survey (crafts). ... | fast early pulsar discoveries: effelsberg follow-up |
dark matter (dm) can consist of very light bosons behaving as a classical scalar field that experiences coherent oscillations. the presence of this dm field would perturb the dynamics of celestial bodies, either because the (oscillating) dm stress tensor modifies the gravitational potentials of the galaxy or if dm is d... | secular effects of ultralight dark matter on binary pulsars |
we report the discovery of a new unidentified extended γ-ray source in the galactic plane named lhaaso j0341+5258 with a pretrial significance of 8.2 standard deviations above 25 tev. the best-fit position is r.a. = 55°34 ± 0°11 and decl. = 52°97 ± 0°07. the angular size of lhaaso j0341+5258 is 0°29 ± 0°06stat ± 0°02sy... | discovery of a new gamma-ray source, lhaaso j0341+5258, with emission up to 200 tev |
cosmic gravitons are expected in the mhz-ghz regions that are currently unreachable by the operating wide-band interferometers and where various classes of electromechanical detectors have been proposed through the years. the minimal chirp amplitude detectable by these instruments is often set on the basis of the sensi... | relic gravitons and high-frequency detectors |
the last decade has seen a leapfrog in the interest of x-ray polarimetry with a number of new polarization measurements in hard x-rays from astrosat, polar, gap, and pogo+. the measurements provide some interesting insights into various astrophysical phenomena such as coronal geometry and disk-jet connection in black h... | hard x-ray polarimetry—an overview of the method, science drivers, and recent findings |
we have carried out the galactic plane pulsar snapshot (gpps) survey by using the five-hundred-meter aperture spherical radio telescope (fast), the most sensitive systematic pulsar survey in the galactic plane. in addition to more than 500 pulsars already discovered through normal periodical search, we report here the ... | the fast galactic plane pulsar snapshot survey. ii. discovery of 76 galactic rotating radio transients and the enigma of rrats |
china's high-speed socioeconomic development has been characterized by rapid urbanization and a series of ecological environment issues, especially air pollution. this paper proposed a comprehensive indicator system for the evaluation of urbanization and the air environment in wuhan, a metropolis in central china, and ... | research on the coupling coordination relationship between urbanization and the air environment: a case study of the area of wuhan |
in order to increase signal-to-noise ratio in optical imaging, most detectors sacrifice resolution to increase pixel size in a confined area, which impedes further development of high throughput holographic imaging. although the pixel super-resolution technique (psr) enables resolution enhancement, it suffers from the ... | plug-and-play pixel super-resolution phase retrieval for digital holography |
we report rebrightening from the be/x-ray binary pulsar ls v +44 17 (also known as rx j0440.9+4431) detected by nicer, swift/bat and maxi/gsc. the pulsar was recently reported to be in an x-ray outburst (atel #15835, #15848). | rebrightening of 1 crab from ls v+44 17 observed by swift/bat and nicer |
pulsars have long been studied in the electromagnetic spectrum. their environments are rich in high-energy cosmic-ray electrons and positrons likely enriching the interstellar medium (ism) with such particles. in this work we use recent cosmic-ray observations from the ams-02, calet, and dampe collaborations to study t... | utilizing cosmic-ray positron and electron observations to probe the averaged properties of milky way pulsars |
the five-hundred-meter aperture spherical radio telescope (fast) is by far the largest telescope of any kind ever built. fast produced its first light in september 2016 and it is now under commissioning, with normal operation to commence in late 2019. during testing and early science operation, fast has started making ... | preface: planning the scientific applications of the five-hundred-meter aperture spherical radio telescope |
magnetars are neutron stars with extremely strong magnetic fields, frequently powering high-energy activity in x-rays. pulsed radio emission following some x-ray outbursts have been detected, albeit its physical origin is unclear. it has long been speculated that the origin of magnetars' radio signals is different from... | atypical radio pulsations from magnetar sgr 1935+2154 |
an ensemble of inspiraling supermassive black hole binaries should produce a stochastic background of very low frequency gravitational waves. this stochastic background is predicted to be a power law, with a gravitational-wave strain spectral index of -2/3, and it should be detectable by a network of precisely timed mi... | the nanograv 11 yr data set: evolution of gravitational-wave background statistics |
massive gas-rich galaxy discs at z ∼ 1-3 host massive star-forming clumps with typical baryonic masses in the range 107-108 m⊙ which can affect the orbital decay and concurrent growth of supermassive black hole (bh) pairs. using a set of high-resolution simulations of isolated clumpy galaxies hosting a pair of unequal-... | supermassive black hole pairs in clumpy galaxies at high redshift: delayed binary formation and concurrent mass growth |
if the ultraluminous source (ulx) m82 x-2 sustains its measured spin-up value of dot{ν }= 10^{-10} s^{-2}, it will become a millisecond pulsar in less than 105 yr. the observed (isotropic) luminosity of 1040 erg s-1 also supports the notion that the neutron star will spin up to a millisecond period upon accreting about... | an ultraluminous nascent millisecond pulsar. |
we report on the subpulse modulation properties of 1198 pulsars using the thousand-pulsar-array programme on meerkat. about 35 per cent of the analysed pulsars exhibit drifting subpulses that are more pronounced towards the death line, consistent with previous studies. we estimate that this common phenomenon is detecta... | the thousand-pulsar-array programme on meerkat - viii. the subpulse modulation of 1198 pulsars |
we universally search for evidence of kinematic and spatial correlation of supernova remnant (snr) and molecular cloud (mc) associations for nearly all snrs in the coverage of the milky way imaging scroll painting co survey, i.e., 149 snrs, 170 snr candidates, and 18 pure pulsar wind nebulae in 1° < l < 230° and ... | a systematic study of associations between supernova remnants and molecular clouds |
we report on the monitoring of the final stage of the outburst from the first galactic ultraluminous x-ray pulsar swift j0243.6+6124, which reached ∼40 eddington luminosities. the main aim of the monitoring program with the swift/xrt telescope was to measure the magnetic field of the neutron star using the luminosity o... | on the magnetic field of the first galactic ultraluminous x-ray pulsar swift j0243.6+6124 |
einstein's theory of general relativity has been extensively tested in weak gravitational fields, mainly with experiments in the solar system and observations of radio pulsars, and current data agree well with the theoretical predictions. nevertheless, there are a number of scenarios beyond einstein's gravity that have... | testing the kerr nature of the supermassive black hole in ark 564 |
we present results of a search for late-time radio emission and fast radio bursts (frbs) from a sample of type-i superluminous supernovae (slsne-i). we used the karl g. jansky very large array to observe 10 slsn-i more than 5 yr old at a frequency of 3 ghz. we searched fast-sampled visibilities for frbs and used the sa... | a search for late-time radio emission and fast radio bursts from superluminous supernovae |
natal supernova kicks, the linear momentum compact remnants receive during their formation, are an essential part of binary population synthesis (bps) models. although these kicks are well supported by evidence, their underlying distributions and incorporation into bps models are uncertain. in this work, we investigate... | new constraints on the bray conservation-of-momentum natal kick model from multiple distinct observations |
bow shock pulsar wind nebulae are a large class of non-thermal synchrotron sources associated to old pulsars that have emerged from their parent supernova remnant and are directly interacting with the interstellar medium. within this class a few objects show extended x-ray features, generally referred as `jets', that d... | on the origin of jet-like features in bow shock pulsar wind nebulae |
we present timing solutions and analyses of 11 pulsars discovered by the five-hundred-meter aperture spherical radio telescope (fast). these pulsars were discovered using an ultrawide bandwidth receiver in drift-scan observations made during the commissioning phase of fast, and were then confirmed and timed using the 6... | an in-depth investigation of 11 pulsars discovered by fast |
the green bank north celestial cap survey is a 350 mhz all-sky survey for pulsars and fast radio transients using the robert c. byrd green bank telescope. to date, the survey has discovered over 190 pulsars, including 33 millisecond pulsars and 24 rotating radio transients. several exotic pulsars have been discovered i... | the green bank northern celestial cap pulsar survey. vi. discovery and timing of psr j1759+5036: a double neutron star binary pulsar |
in this work, we investigate neutron stars (ns) in f (r ,lm) theory of gravity for the case f (r ,lm) =r +lm+σ r lm , where r is the ricci scalar and lm the lagrangian matter density. in the term σ r lm , σ represents the coupling between the gravitational and particles fields. for the first time the hydrostatic equili... | neutron stars in f (r ,lm) gravity with realistic equations of state: joint-constrains with gw170817, massive pulsars, and the psr j0030+0451 mass-radius from nicer data |
when astrophysical jets were discovered one hundred years ago, the field of numerical simulations did not yet exit. since the arrival of programmable computers though, numerical simulations have increasingly become an indispensable tool for dealing with "tough nut" problems which involve complex dynamic and non-linear ... | numerical simulations of jets |
searching for periodic non-accelerated signals in the presence of ideal white noise using the fully phase-coherent fast-folding algorithm (ffa) is theoretically established as a more sensitive search method than the fast fourier transform (fft) search with incoherent harmonic summing. in this paper, we present a compar... | the gmrt high resolution southern sky survey for pulsars and transients. iii. searching for long-period pulsars |
black widows are extreme millisecond pulsar binaries where the pulsar wind ablates their low-mass companion stars. in the optical range, their light curves vary periodically due to the high irradiation and tidal distortion of the companion, which allows us to infer the binary parameters. we present simultaneous multiba... | a black widow population dissection through hipercam multiband light-curve modelling |
the possible signatures of the presence of hyperons inside neutron stars are discussed within a bayesian inference framework applied to a set of models based on a density dependent relativistic mean field description of hadronic matter. nuclear matter properties, hypernuclei properties and observational information are... | bayesian inference of signatures of hyperons inside neutron stars |
we present the discovery of 528.6 hz pulsations in the new x-ray transient maxi j1816-195. using nicer, we observed the first recorded transient outburst from the neutron star low-mass x-ray binary maxi j1816-195 over a period of 28 days. from a timing analysis of the 528.6 hz pulsations, we find that the binary system... | the discovery of the 528.6 hz accreting millisecond x-ray pulsar maxi j1816-195 |
in the last few years, the nicer collaboration has provided mass and radius inferences, via pulse profile modeling, for two pulsars: psr j0030+0451 and psr j0740+6620. given the importance of these results for constraining the equation of state of dense nuclear matter, it is crucial to validate them and test their robu... | x-psi parameter recovery for temperature map configurations inspired by psr j0030+0451 |
the last five years have seen remarkable progress in our quest to determine the equation of state of neutron rich matter. recent advances across the theoretical, experimental, and observational landscape have been incorporated in a bayesian framework to refine existing covariant energy density functionals previously ca... | bayesian refinement of covariant energy density functionals |
<p id="par1">two classes of x-ray/gamma-ray sources, the soft gamma repeaters<index-term id="iterm1"><term>soft gamma repeater (sgr)</term></index-term> and the anomalous x-ray pulsars<index-term id="iterm2"><term>anomalous x-ray pulsar (axp)</term></index-term> hav... | millisecond magnetars |
hard, nonthermal, persistent pulsed x-ray emission extending between 10 and ∼150 kev has been observed in nearly 10 magnetars. for inner-magnetospheric models of such emission, resonant inverse compton scattering of soft thermal photons by ultrarelativistic charges is the most efficient production mechanism. we present... | resonant inverse compton scattering spectra from highly magnetized neutron stars |
we present the first survey results of hard x-ray point sources in the galactic center (gc) region by nustar. we have discovered 70 hard (3-79 kev) x-ray point sources in a 0.6 deg{}2 region around sgr a* with a total exposure of 1.7 ms, and 7 sources in the sgr b2 field with 300 ks. we identify clear chandra counterpa... | nustar hard x-ray survey of the galactic center region. ii. x-ray point sources |
in theories of gravity that include a scalar field, a compact object's scalar charge is a crucial quantity since it controls dipole radiation, which can be strongly constrained by pulsar timing and gravitational wave observations. however, in most such theories, computing the scalar charge requires simultaneously solvi... | black hole scalar charge from a topological horizon integral in einstein-dilaton-gauss-bonnet gravity |
a neutron star was first detected as a pulsar in 1967. it is one of the most mysterious compact objects in the universe, with a radius of the order of 10 km and masses that can reach two solar masses. in fact, neutron stars are star remnants, a kind of stellar zombie (they die, but do not disappear). in the last decade... | a neutron star is born |
magnetized particle motion around black holes in conformal gravity immersed in asymptotically uniform magnetic field has been studied. we have also analyzed the behavior of magnetic fields near the horizon of the black hole in conformal gravity and shown that with the increase of conformal parameters l and n the value ... | magnetized particle motion around black holes in conformal gravity: can magnetic interaction mimic spin of black holes? |
the dynamic and secondary spectra of many pulsars show evidence for long-lived, aligned images of the pulsar that are stationary on a thin scattering sheet. one explanation for this phenomenon considers the effects of wave crests along sheets in the ionized interstellar medium, such as those due to alfvén waves propaga... | predicting pulsar scintillation from refractive plasma sheets |
in this work, test particle dynamics around a static regular bardeen black hole (bh) in anti-de sitter spacetime has been studied. it has been shown for neutral test particles that parameters of a regular bardeen black hole in anti-de sitter spacetime can mimic the rotation parameter of the kerr metric up to the value ... | regular bardeen black holes in anti-de sitter spacetime versus kerr black holes through particle dynamics |
we explore magnetic field configurations that lead to the formation of magnetic spots on the surface of neutron stars and the displacement of the magnetic dipole axis. we find that a toroidally dominated magnetic field is essential for the generation of a single spot with a strong magnetic field. once a spot forms, it ... | magnetic axis drift and magnetic spot formation in neutron stars with toroidal fields |
most of ultraluminous x-ray sources are thought to be objects accreting above their eddington limits. in the recently identified class of ultraluminous x-ray pulsars, accretor is a neutron star and thus has a fairly small mass with a small eddington limit. the accretion disc structure around such an object affects impo... | super-eddington accretion on to a magnetized neutron star |
the chime telescope (the canadian hydrogen intensity mapping experiment) recently built in penticton, canada, is currently being commissioned. originally designed as a cosmology experiment, it was soon recognized that chime has the potential to simultaneously serve as an incredibly useful radio telescope for pulsar sci... | pulsar science with the chime telescope |
aims: we study γ-ray emission from the shell-type supernova remnant (snr) rx j0852.0-4622 to better characterize its spectral properties and its distribution over the snr.methods: the analysis of an extended high energy spectroscopic system (h.e.s.s.) data set at very high energies (e > 100 gev) permits detailed stu... | deeper h.e.s.s. observations of vela junior (rx j0852.0-4622): morphology studies and resolved spectroscopy |
we show the existence and investigate the location of the special point (sp) in which hybrid neutron star mass-radius (m-r) curves have to cross each other when they belong to a class of hybrid equation of state (eos) constructed with generic constant-speed-of-sound (css) quark matter models for which the onset deconfi... | the special point on the hybrid star mass-radius diagram and its multi-messenger implications |
the galactic center excess (gce) is an extended gamma-ray source in the central region of the galaxy found in fermi large area telescope (fermi-lat) data. one of the leading explanations for the gce is an unresolved population of millisecond pulsars (msps) in the galactic bulge. due to differing star formation historie... | comparing the galactic bulge and galactic disk millisecond pulsars |
the cosmic evolution of the neutron-star merger (nsm) rate can be deduced from the observed cosmic star formation rate. this allows us to estimate the rate expected in the horizon of the gravitational wave detectors advanced virgo and advanced ligo and to compare those rates with independent predictions. in this contex... | cosmic neutron-star merger rate and gravitational waves constrained by the r-process nucleosynthesis |
despite the growing number of gamma-ray sources detected by the fermi-large area telescope (lat), about one-third of the sources in each survey remains of uncertain type. we present a new deep neural network approach for the classification of unidentified or unassociated gamma-ray sources in the last release of the fer... | classification of fermi-lat sources with deep learning using energy and time spectra |
recent pulsar timing data reported by the nanograv collaboration indicates the existence of a stochastic gravitational wave (gw) background at a frequency $f\sim 10^{-8}~\rm hz$. we show that a dark sector consisting of a standard model (sm) gauge singlet fermion $\chi$ and a singlet scalar $\phi$, both charged under a... | implications of nanograv results and uv freeze-in in a fast-expanding universe |
a new window is opening in high-energy astronomy: x-ray polarimetry. with many missions currently under development and scheduled to launch as early as 2021, observations of the x-ray polarization of accreting x-ray pulsars will soon be available. as polarization is particularly sensitive to the geometry of the emissio... | polarization of accreting x-ray pulsars. i. a new model |
the maximum mass of a neutron star has important implications across multiple research fields, including astrophysics, nuclear physics and gravitational wave astronomy. compact binary millisecond pulsars (with orbital periods shorter than about a day) are a rapidly-growing pulsar population, and provide a good opportun... | super-massive neutron stars and compact binary millisecond pulsars |
large-area sky surveys show that massive galaxies undergo at least one major merger in a hubble time. ongoing pulsar timing array (pta) experiments are aimed at measuring the gravitational-wave (gw) emission from binary supermassive black holes (smbhs) at the centres of galaxy merger remnants. in this paper, using the ... | prospects for gravitational-wave detection and supermassive black hole astrophysics with pulsar timing arrays |
using the nine-year radio-pulsar timing data set from the north american nanohertz observatory for gravitational waves (nanograv), collected at arecibo observatory and the green bank telescope, we have measured the positions, proper motions, and parallaxes for 37 millisecond pulsars. we report twelve significant parall... | the nanograv nine-year data set: astrometric measurements of 37 millisecond pulsars |
pulsars may either be spun up or down by hydrodynamic instabilities during the supernova explosion of massive stars. besides rapidly rotating cases related to bipolar explosions, stellar rotation may affect the explosion of massive stars in the more common situations where the centrifugal force is minor. using 2d simul... | are pulsars spun up or down by sasi spiral modes? |
the phenomenon of subpulse drifting may hold the key to understanding the pulsar emission mechanism. here, we report on new observations of psr j0034-0721 (b0031-07) carried out with the murchison widefield array at 185 {mhz}. we observe three distinct drift modes whose “vertical” drift band separations (p 3) and relat... | low-frequency observations of the subpulse drifter psr j0034-0721 with the murchison widefield array |
vortex-mediated mutual friction governs the coupling between the superfluid and normal components in neutron star interiors. by, for example, comparing precise timing observations of pulsar glitches with theoretical predictions it is possible to constrain the physics in the interior of the star, but to do so an accurat... | a universal formula for the relativistic correction to the mutual friction coupling time-scale in neutron stars |
as radio telescopes become more sensitive, radio frequency interference (rfi) is becoming more important for interesting signals of radio astronomy. there is a demand for developing an automatic, accurate and efficient rfi mitigation method. therefore, we have investigated an rfi detection algorithm. first, we introduc... | radio frequency interference mitigation based on the asymmetrically reweighted penalized least squares and sumthreshold method |
pulsar magnetospheres admit nonstationary vacuum gaps that are characterized by nonvanishing e .b . the vacuum gaps play an important role in plasma production and electromagnetic wave emission. we show that these gaps generate axions whose energy is set by the gap oscillation frequency. the density of axions produced ... | axion production in pulsar magnetosphere gaps |
magnetars are young, rotating neutron stars that possess larger magnetic fields ($b$ $\approx$ $10^{13}$-$10^{15}$ g) and longer rotational periods ($p$ $\approx$ 1-12 s) than ordinary pulsars. in contrast to rotation-powered pulsars, magnetar emission is thought to be fueled by the evolution and decay of their powerfu... | bright x-ray and radio pulses from a recently reactivated magnetar |
we present the detection of 107 pulsars with interstellar scintillation arcs at 856-1712 mhz, observed with the meerkat thousand pulsar array programme. scintillation arcs appear to be ubiquitous in clean, high s/n observations, their detection mainly limited by short observing durations and coarse frequency channel re... | the thousand pulsar array programme on meerkat - x. scintillation arcs of 107 pulsars |
very faint x-ray transients (vfxts) are x-ray transients with peak x-ray luminosities (lx) of l$_x \lesssim 10^{36}$ erg s-1, which are not well understood. we carried out a survey of 16 deg2 of the galactic bulge with the swift observatory, using short (60 s) exposures, and returning every 2 weeks for 19 epochs in 201... | the swift bulge survey: motivation, strategy, and first x-ray results |
sgr j1935+2154, the host magnetar of the galactic frb200428 (atel #13681, #13684), was reported to be radio-active again on 2020 oct 8th by chime/frb team (atel #14074, #14080). | fast detection of radio bursts and pulsed emission from sgr j1935+2154 |
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