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gravitational waves are a radically new way to peer into the darkest depths of the cosmos. pulsars can be used to make direct detections of gravitational waves through precision timing. when a gravitational wave passes between a pulsar and the earth, it stretches and squeezes the intermediate space-time, leading to dev... | the nanohertz gravitational wave astronomer |
we present 3d full-sphere supernova simulations of non-rotating low-mass (∼9 m⊙) progenitors, covering the entire evolution from core collapse through bounce and shock revival, through shock breakout from the stellar surface, until fallback is completed several days later. we obtain low-energy explosions (∼0.5-1.0 × 10... | three-dimensional models of core-collapse supernovae from low-mass progenitors with implications for crab |
in this article we study the hydrostatic equilibrium configuration of neutron stars and strange stars, whose fluid pressure is computed from the equations of state p=ωρ5/3 and p=0.28(ρ-4script b), respectively, with ω and script b being constants and ρ the energy density of the fluid. we start by deriving the hydrostat... | stellar equilibrium configurations of compact stars in f(r,t) theory of gravity |
magnetars are neutron stars in which a strong magnetic field is the main energy source. about two dozens of magnetars, plus several candidates, are currently known in our galaxy and in the magellanic clouds. they appear as highly variable x-ray sources and, in some cases, also as radio and/or optical pulsars. their spi... | magnetars: properties, origin and evolution |
the event horizon telescope is a millimeter vlbi array that is taking the first horizon-scale pictures of the black hole in the center of the m87 galaxy and, in the near future, of the one in the center of the milky way. measurements of the shape and size of the shadows cast by the black holes on the surrounding emissi... | testing general relativity with the event horizon telescope |
einstein's theory of gravity—the general theory of relativity1—is based on the universality of free fall, which specifies that all objects accelerate identically in an external gravitational field. in contrast to almost all alternative theories of gravity2, the strong equivalence principle of general relativity require... | universality of free fall from the orbital motion of a pulsar in a stellar triple system |
we search for a stochastic gravitational wave background (sgwb) generated by a network of cosmic strings using six millisecond pulsars from data release 2 (dr2) of the european pulsar timing array (epta). we perform a bayesian analysis considering two models for the network of cosmic string loops, and compare it to a s... | practical approaches to analyzing pta data: cosmic strings with six pulsars |
we report the discovery and initial follow-up of a double neutron star (dns) system, psr j1946+2052, with the arecibo l-band feed array pulsar (palfa) survey. psr j1946+2052 is a 17 ms pulsar in a 1.88 hr, eccentric (e = 0.06) orbit with a ≳1.2 m ⊙ companion. we have used the jansky very large array to localize psr j19... | palfa discovery of a highly relativistic double neutron star binary |
supermassive black hole binaries (smbhs) are a fascinating byproduct of galaxy mergers in the hierarchical universe. in the last stage of their orbital evolution, gravitational wave radiation drives the binary inspiral and produces the loudest siren awaiting to be detected by gravitational wave observatories. periodica... | tick-tock: the imminent merger of a supermassive black hole binary |
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. in this letter we demonstrate that coherent radiation can be directly generated in nonstationary pair plasma discharges which are responsible for filling the pulsar... | origin of pulsar radio emission |
the ligo/virgo detection of the gravitational waves from a binary merger system, gw170817, has put a clean and strong constraint on the tidal deformability of the merging objects. from this constraint, deep insights can be obtained in compact star equation of states, which has been one of the most puzzling problems for... | constraints on interquark interaction parameters with gw170817 in a binary strange star scenario |
the detection of cyclotron resonance scattering features (crsfs) is the only way to directly and reliably measure the magnetic field near the surface of a neutron star (ns). the broad energy coverage and large collection area of insight-hxmt in the hard x-ray band allowed us to detect the crsf with the highest energy k... | insight-hxmt discovery of the highest-energy crsf from the first galactic ultraluminous x-ray pulsar swift j0243.6+6124 |
we analyze the statistics of pulse arrival times in fast radio burst (frb) 121102 and demonstrate that they are remarkably similar to statistics of magnetar high-energy short bursts. motivated by this correspondence, we propose that repeating frbs are generated during short bursts in the closed field line zone of magne... | repeating fast radio bursts from magnetars with low magnetospheric twist |
recent work has shown that axions can be efficiently produced via non-stationary pair plasma discharges in the polar cap region of pulsars. here, we point out that for axion masses $10^{-9} \, {\rm ev} \lesssim m_a \lesssim 10^{-4} \, \rm ev$, a sizable fraction of the sourced axion population will be gravitationally c... | axion clouds around neutron stars |
we obtain a new static model of the tov equation for an anisotropic fluid distribution by imposing the karmarkar condition. in order to close the system of equations we postulate an interesting form for the g_{rr} gravitational potential, which allows us to solve for g_{tt} metric component via the karmarkar condition.... | physical viability of fluid spheres satisfying the karmarkar condition |
we present the results of psrπ, a large astrometric project targeting radio pulsars using the very long baseline array (vlba). from our astrometric database of 60 pulsars, we have obtained parallax-based distance measurements for all but 3, with a parallax precision that is typically ∼45 μas and approaches 10 μas in th... | microarcsecond vlbi pulsar astrometry with psrπ ii. parallax distances for 57 pulsars |
we study properties of luminous x-ray pulsars using a simplified model of the accretion column. the maximal possible luminosity is calculated as a function of the neutron star (ns) magnetic field and spin period. it is shown that the luminosity can reach values of the order of 1040 erg s-1 for the magnetar-like magneti... | on the maximum accretion luminosity of magnetized neutron stars: connecting x-ray pulsars and ultraluminous x-ray sources |
the recent discovery of a galactic fast radio burst (frb) occurring simultaneously with an x-ray burst (xrb) from the galactic magnetar sgr j1935+2154 implies that at least some frbs arise from magnetar activities. we propose that frbs are triggered by crust fracturing of magnetars, with the burst event rate depending ... | fast radio bursts and their high-energy counterparts from magnetar magnetospheres |
a large number of extremely low-mass helium white dwarfs (elm wds) have been discovered in recent years. the majority of them are found in close binary systems suggesting they are formed either through a common-envelope phase or via stable mass transfer in a low-mass x-ray binary (lmxb) or a cataclysmic variable (cv) s... | models of low-mass helium white dwarfs including gravitational settling, thermal and chemical diffusion, and rotational mixing |
pulsar timing array collaborations, such as the north american nanohertz observatory for gravitational waves (nanograv), are seeking to detect nanohertz gravitational waves emitted by supermassive black hole binaries formed in the aftermath of galaxy mergers. we have searched for continuous waves from individual circul... | the nanograv 12.5 yr data set: bayesian limits on gravitational waves from individual supermassive black hole binaries |
we investigate the propagation of electromagnetic radiation in the magnetic dual chiral density wave (mdcdw) phase of dense quark matter. considering the theory of low-energy fluctuations in this phase, we show how linearly polarized photons reaching the mdcdw medium couple to the fluctuation field to produce two hybri... | axion-polaritons in the magnetic dual chiral density wave phase of dense qcd |
the existence of a ‘density cusp’—a localized increase in number—of stellar-mass black holes near a supermassive black hole is a fundamental prediction of galactic stellar dynamics. the best place to detect such a cusp is in the galactic centre, where the nearest supermassive black hole, sagittarius a*, resides. as man... | a density cusp of quiescent x-ray binaries in the central parsec of the galaxy |
cosmic strings are topological defects which can be formed in grand unified theory scale phase transitions in the early universe. they are also predicted to form in the context of string theory. the main mechanism for a network of nambu-goto cosmic strings to lose energy is through the production of loops and the subse... | constraints on cosmic strings using data from the first advanced ligo observing run |
this paper presents the results of a search for generic short-duration gravitational-wave transients in data from the third observing run of advanced ligo and advanced virgo. transients with durations of milliseconds to a few seconds in the 24-4096 hz frequency band are targeted by the search, with no assumptions made ... | all-sky search for short gravitational-wave bursts in the third advanced ligo and advanced virgo run |
we have detected a bright radio burst from frb 20200120e with the nasa deep space network (dsn) 70 m dish (dss-63) at radio frequencies between 2.2 and 2.3 ghz. this repeating fast radio burst (frb) is reported to be associated with a globular cluster in the m81 galactic system. with high time resolution recording, low... | a bright fast radio burst from frb 20200120e with sub-100 nanosecond structure |
general relativity has passed all solar system experiments and neutron star based tests, such as binary pulsar observations, with flying colors. a more exotic arena for testing general relativity is in systems that contain one or more black holes. black holes are the most compact objects in the universe, providing prob... | black hole based tests of general relativity |
we present the design, implementation, and performance of the digital pulsar observing system constructed for the canadian hydrogen intensity mapping experiment (chime). using accelerated computing, this system processes independent, digitally steered beams formed by the chime correlator to simultaneously observe up to... | the chime pulsar project: system overview |
recent measurements of the geminga and b 0656 +14 pulsars by the gamma-ray telescope hawc (along with earlier measurements by milagro) indicate that these objects generate significant fluxes of very high-energy electrons. in this paper, we use the very high-energy gamma-ray intensity and spectrum of these pulsars to ca... | hawc observations strongly favor pulsar interpretations of the cosmic-ray positron excess |
we perform global particle-in-cell simulations of pulsar magnetospheres, including pair production, ion extraction from the surface, frame-dragging corrections, and high-energy photon emission and propagation. in the case of oblique rotators, the effects of general relativity increase the fraction of the open field lin... | ab-initio pulsar magnetosphere: particle acceleration in oblique rotators and high-energy emission modeling |
we review the physics of relativistic shocks, which are often invoked as the sources of non-thermal particles in pulsar wind nebulae (pwne), gamma-ray bursts (grbs), and active galactic nuclei (agn) jets, and as possible sources of ultra-high energy cosmic-rays. we focus on particle acceleration and magnetic field gene... | relativistic shocks: particle acceleration and magnetization |
we propose a new extra but non-cosmological explanation for fast radio bursts (frbs) based on very young pulsars in supernova remnants. within a few hundred years of a core-collapse supernova, the ejecta is confined within ∼1 pc, providing a high enough column density of free electrons for the observed 375-1600 pc cm-3... | non-cosmological frbs from young supernova remnant pulsars |
benefitting from the unequaled precision of the pulsar timing technique, binary pulsars are important testbeds of gravity theories, providing some of the tightest bounds on alternative theories of gravity. one class of well-motivated alternative gravity theories, the scalar-tensor gravity, predict large deviations from... | closing a spontaneous-scalarization window with binary pulsars |
we present relativistic analyses of 9257 measurements of times-of-arrival from the first binary pulsar, psr b1913+16, acquired over the last 35 years. the determination of the “keplerian” orbital elements plus two relativistic terms completely characterizes the binary system, aside from an unknown rotation about the li... | relativistic measurements from timing the binary pulsar psr b1913+16 |
neutron stars are natural physical laboratories allowing us to study a plethora of phenomena in extreme conditions. in particular, these compact objects can have very strong magnetic fields with non-trivial origin and evolution. in many respects, its magnetic field determines the appearance of a neutron star. thus, und... | evolution of neutron star magnetic fields |
we have used the central 44 antennas of the new 64-dish meerkat radio telescope array to conduct a deep search for new pulsars in the core of nine globular clusters (gcs). this has led to the discovery of eight new millisecond pulsars in six different clusters. two new binaries, 47 tuc ac and 47 tuc ad, are eclipsing '... | eight new millisecond pulsars from the first meerkat globular cluster census |
we show that an ultralight primordial black hole (pbh) dominated phase makes blue-tilted inflationary gravitational waves (bgw) compatible with the recent detection of an nhz stochastic gw background by pulsar-timing arrays (ptas), for high reheating temperatures. this pbh-dominated phase suppresses the bgw spectrum vi... | explaining pta data with inflationary gws in a pbh-dominated universe |
the abundance of primordial black holes changes in the presence of local non-gaussianity. a positive nonlinear parameter fnl increases the abundance while a negative one reduces it. we show that in nonattractor single-field models of inflation which enhance the curvature power spectrum and may give rise to primordial b... | sign of non-gaussianity and the primordial black holes abundance |
with the enhancement mechanism provided by a noncanonical kinetic term with a peak, the amplitude of primordial curvature perturbations can be enhanced by seven orders of magnitude at small scales while keeping to be consistent with observations at large scales. the peak function and inflationary potential are not rest... | primordial black holes and scalar-induced secondary gravitational waves from inflationary models with a noncanonical kinetic term |
in this work we present an exact solution of the einstein-maxwell field equations describing compact charged objects within the framework of classical general relativity. our model is constructed by embedding a four-dimensional spherically symmetric static metric into a five-dimensional flat metric. the source term for... | generating physically realizable stellar structures via embedding |
we present broadband x-ray analyses of a sample of bright ultraluminous x-ray sources (ulx) with the goal of investigating the spectral similarity of this population to the known ulx pulsars, m82 x-2, ngc 7793 p13, and ngc 5907 ulx. we perform a phase-resolved analysis of the broadband xmm-newton+nustar data set of ngc... | evidence for pulsar-like emission components in the broadband ulx sample |
a graduate-level textbook on the astrophysics of binary star systems and their evolution. physics of binary star evolution is an up-to-date textbook on the astrophysics and evolution of binary star systems. theoretical astrophysicists thomas tauris and edward van den heuvel cover a wide range of phenomena and processes... | physics of binary star evolution. from stars to x-ray binaries and gravitational wave sources |
we study a specific model of anisotropic strange stars in the modified f(r,t)-type gravity by deriving solutions to the modified einstein field equations representing a spherically symmetric anisotropic stellar object. we take a standard assumption that f(r,t)=r+2χ t, where r is ricci scalar, t is the trace of the ener... | exploring physical features of anisotropic strange stars beyond standard maximum mass limit in f(r,t) gravity |
an excess of $\gamma$-ray emission from the galactic center (gc) region with respect to predictions based on a variety of interstellar emission models and $\gamma$-ray source catalogs has been found by many groups using data from the {\it fermi} large area telescope (lat). several interpretations of this excess have be... | characterizing the population of pulsars in the inner galaxy with the fermi large area telescope |
isolated neutron stars that are asymmetric with respect to their spin axis are possible sources of detectable continuous gravitational waves. this paper presents a fully coherent search for such signals from eighteen pulsars in data from ligo and virgo's third observing run (o3). for known pulsars, efficient and sensit... | narrowband searches for continuous and long-duration transient gravitational waves from known pulsars in the ligo-virgo third observing run |
we have searched for continuous gravitational wave (cgw) signals produced by individually resolvable, circular supermassive black hole binaries (smbhbs) in the latest european pulsar timing array (epta) data set, which consists of ultraprecise timing data on 41-ms pulsars. we develop frequentist and bayesian detection ... | european pulsar timing array limits on continuous gravitational waves from individual supermassive black hole binaries |
a physically realistic stellar model with a simple expression for the energy density and conformally flat interior is found. the relations between the different conditions are used without graphic proofs. it may represent a real pulsar. | a conformally flat realistic anisotropic model for a compact star |
we perform a direct search for an isotropic stochastic gravitational-wave background (sgwb) produced by cosmic strings in the parkes pulsar timing array (ppta) data release 2 (dr2). we find no evidence for such an sgwb, and therefore place a 95% confidence level upper limit on the cosmic string tension, g μ, as a funct... | search for the gravitational-wave background from cosmic strings with the parkes pulsar timing array second data release |
motivated by the direct discovery of gravitational waves (gws) from black holes and neutron stars, there is a growing interest in investigating gws from other sources. among them, gws from cosmic strings are particularly fascinating since they naturally appear in a large class of grand unified theories (guts). remarkab... | probing minimal grand unification through gravitational waves, proton decay, and fermion masses |
new radio (meerkat and parkes) and x-ray (xmm-newton, swift, chandra, and nustar) observations of psr j1622-4950 indicate that the magnetar, in a quiescent state since at least early 2015, reactivated between 2017 march 19 and april 5. the radio flux density, while variable, is approximately 100× larger than during its... | revival of the magnetar psr j1622-4950: observations with meerkat, parkes, xmm-newton, swift, chandra, and nustar |
we examine the spectra of 23 fast radio bursts (frbs) detected in a fly’s-eye survey with the australian ska pathfinder, including those of three bursts not previously reported. the mean spectral index of α =-{1.5}-0.3+0.2 (fν∝ να ) is close to that of the galactic pulsar population. the sample is dominated by bursts e... | the spectral properties of the bright fast radio burst population |
we revisit the predictions for the merger rate of massive black hole binaries detectable by the laser interferometer space antenna (lisa) and their background signal for pulsar-timing arrays. we focus on the effect of the delays between the merger of galaxies and the final coalescence of black hole binaries, and on sup... | massive black hole merger rates: the effect of kiloparsec separation wandering and supernova feedback |
we report constraints on the sources of ultrahigh-energy cosmic rays (uhecrs) above 1 09 gev , based on an analysis of seven years of icecube data. this analysis efficiently selects very high- energy neutrino-induced events which have deposited energies from 5 ×1 05 gev to above 1 011 gev . two neutrino-induced events ... | constraints on ultrahigh-energy cosmic-ray sources from a search for neutrinos above 10 pev with icecube |
primordial black holes (pbhs) can constitute the predominant fraction of dark matter (dm) if pbhs reside in the currently unconstrained "sublunar" mass range. pbhs originating from scalar perturbations generated during inflation can naturally appear with a broad spectrum in a class of models. the resulting stochastic g... | testing stochastic gravitational wave signals from primordial black holes with optical telescopes |
quantum fluctuations of the gravitational field in the early universe, amplified by inflation, produce a primordial gravitational-wave background across a broad frequency band. we derive constraints on the spectrum of this gravitational radiation, and hence on theories of the early universe, by combining experiments th... | gravitational-wave cosmology across 29 decades in frequency |
we present a search for gravitational waves from 222 pulsars with rotation frequencies ≳10 hz. we use advanced ligo data from its first and second observing runs spanning 2015-2017, which provides the highest-sensitivity gravitational-wave data so far obtained. in this search we target emission from both the l = m = 2 ... | searches for gravitational waves from known pulsars at two harmonics in 2015-2017 ligo data |
the black hole merging rates inferred after the gravitational-wave detections by advanced ligo/virgo and the relatively high mass of the progenitors are consistent with models of dark matter made of massive primordial black holes (pbh). pbh binaries emit gravitational waves in a broad range of frequencies that will be ... | detecting the gravitational wave background from primordial black hole dark matter |
we investigate a mechanism of primordial black hole (pbh) formation that avoids any dependence on specific inflationary features or exotic physics. in this scenario, the required large curvature fluctuations leading to pbh formation are generated after inflation by the quantum fluctuations of a light stochastic spectat... | primordial black holes without fine-tuning from a light stochastic spectator field |
recently we found compelling evidence for a gravitational wave background with hellings and downs (hd) correlations in our 15-year data set. these correlations describe gravitational waves as predicted by general relativity, which has two transverse polarization modes. however, more general metric theories of gravity c... | the nanograv 15-year data set: search for transverse polarization modes in the gravitational-wave background |
the recent nicer measurement of the radius of the neutron star psr j0740+6620, and the inferred small variation of radii from 1.4 to 2.1 m ⊙, reveal key features of the equation of state of neutron star matter. the pressure rises rapidly in the regime of baryon density n ~ 2-4 times nuclear saturation density, n 0-the ... | implications of nicer for neutron star matter: the qhc21 equation of state |
we present a monte carlo-based population synthesis study of fast radio burst (frb) dispersion and scattering focusing on the first catalog of sources detected with the canadian hydrogen intensity mapping experiment fast radio burst (chime/frb) project. we simulate intrinsic properties and propagation effects for a var... | modeling fast radio burst dispersion and scattering properties in the first chime/frb catalog |
the galactic center excess (gce) remains one of the most intriguing discoveries from the fermi large area telescope (lat) observations. we revisit the characteristics of the gce by first producing a new set of high-resolution galactic diffuse gamma-ray emission templates. this diffuse emission, which accounts for the b... | return of the templates: revisiting the galactic center excess with multimessenger observations |
we study graviton-photon conversion in magnetosphere of a pulsar and explore the possibility of detecting high frequency gravitational waves with pulsar observations. it is shown that conversion of one polarization mode of photons can be enhanced significantly due to strong magnetic fields around a pulsar. we also cons... | probing high frequency gravitational waves with pulsars |
we study possible effects of a dark matter (dm) core on the maximum mass of a neutron star (ns), on the mass-radius relation and on the ns tidal deformability parameter λ . we show that all these quantities would in general be reduced in the presence of a dm core. in particular, our calculations indicate that the prese... | dark matter effects on neutron star properties |
binaries comprised of a neutron star (ns) and a black hole (bh) have so far eluded observations as pulsars and with gravitational waves (gws). we model the formation and evolution of these ns+bh binaries - including pulsar evolution - using the binary population synthesis code compas. we predict the presence of a total... | modelling neutron star-black hole binaries: future pulsar surveys and gravitational wave detectors |
pulsars are known for their superb timing precision, although glitches can interrupt the regular timing behavior when the stars are young. these glitches are thought to be caused by interactions between normal and superfluid matter in the crust of the star. however, glitching pulsars such as vela have been shown to req... | pinning down the superfluid and measuring masses using pulsar glitches |
natal kicks are a matter of debate and they significantly affect the merger rate density of compact objects. here, we present a new simple formalism for natal kicks of neutron stars (nss) and black holes (bhs). we describe the magnitude of the kick as {v}kick∝ {f}h05 mej mrem-1, where fh05 is a normalization factor, dr... | revising natal kick prescriptions in population synthesis simulations |
screening mechanisms are essential features of dark energy models mediating a fifth force on large scales. we study the regime of strong scalar field nonlinearities, known as vainshtein screening, in the most general scalar-tensor theories propagating a single scalar degree of freedom. we first develop an effective app... | vainshtein screening in scalar-tensor theories before and after gw170817: constraints on theories beyond horndeski |
we explore the implications of the recent radius determination of psr j 0740 +6620 by the nicer experiment, combined with the neutron skin measurement by the prex-ii experiment and the associated inference of the slope of symmetry energy, for the structure of hybrid stars with a strong first-order phase transition from... | relativistic hybrid stars in light of the nicer psr j 0740 +6620 radius measurement |
we present the result of searches for gravitational waves from 200 pulsars using data from the first observing run of the advanced ligo detectors. we find no significant evidence for a gravitational-wave signal from any of these pulsars, but we are able to set the most constraining upper limits yet on their gravitation... | first search for gravitational waves from known pulsars with advanced ligo |
if the black holes detected by ligo/virgo are primordial black holes (pbhs) sourcing from a large primordial curvature perturbation on small scales, the corresponding induced gravitational waves (gws) would peak at nanohertz that is detectable by the current and future observations of pulsar timing array (pta). in this... | pulsar timing array constraints on the induced gravitational waves |
pulsars act as accurate clocks, sensitive to gravitational redshift and acceleration induced by transiting clumps of matter. we study the sensitivity of pulsar timing arrays (ptas) to single transiting compact objects, focusing on primordial black holes and compact subhalos in the mass range from 10-12 m⊙ to well above... | pulsar timing probes of primordial black holes and subhalos |
cosmic rays (protons and other atomic nuclei) are believed to gain energies of petaelectronvolts (pev) and beyond at astrophysical particle accelerators called `pevatrons' inside our galaxy. although a characteristic feature of a pevatron is expected to be a hard gamma-ray energy spectrum that extends beyond 100 terael... | potential pevatron supernova remnant g106.3+2.7 seen in the highest-energy gamma rays |
the strong magnetic field of neutron stars is intimately coupled to the observed temperature and spectral properties, as well as to the observed timing properties (distribution of spin periods and period derivatives). thus, a proper theoretical and numerical study of the magnetic field evolution equations, supplemented... | magnetic, thermal and rotational evolution of isolated neutron stars |
the aligo detection of the black-hole binary gw150914 opens a new era for probing extreme gravity. many gravity theories predict the emission of dipole gravitational radiation by binaries. this is excluded to high accuracy in binary pulsars, but entire classes of theories predict this effect predominantly (or only) in ... | theory-agnostic constraints on black-hole dipole radiation with multiband gravitational-wave astrophysics |
nanograv and other pulsar timing arrays (ptas) have discovered a common-spectrum process in the nhz range that may be due to gravitational waves (gws): if so, they are likely to have been generated by black hole (bh) binaries with total masses > 109 m⊙. using the extended press-schechter formalism to model the galac... | prospects for future binary black hole gravitational wave studies in light of pta measurements |
dark matter (dm) from the galactic halo can accumulate in neutron stars and transmute them into sub-2.5 m⊙ black holes if the dark matter particles are heavy, stable, and have interactions with nucleons. we show that nondetection of gravitational waves from mergers of such low-mass black holes can constrain the interac... | can ligo detect nonannihilating dark matter? |
very recently the nicer collaboration published the first-ever accurate measurement of mass and radius together for psr j0030+0451, a nearby isolated quickly rotating neutron star (ns). in this work we set the joint constraints on the equation of state (eos) and some bulk properties of nss with the data of psr j0030+04... | psr j0030+0451, gw170817, and the nuclear data: joint constraints on equation of state and bulk properties of neutron stars |
results are presented of searches for continuous gravitational waves from 20 accreting millisecond x-ray pulsars with accurately measured spin frequencies and orbital parameters, using data from the third observing run of the advanced ligo and advanced virgo detectors. the search algorithm uses a hidden markov model, w... | search for continuous gravitational waves from 20 accreting millisecond x-ray pulsars in o3 ligo data |
the main objective of the paper is to provide a new family of solutions of embedding class one describing the interior of a spherically symmetric anisotropic stellar configuration. for n =6 ,8 ,10 and 12, all the physical parameters are well-behaved within the stellar interior and our model satisfies all the required c... | stellar modelling of psr j1614-2230 using the karmarkar condition |
we study exact models for anisotropic gravitating stars with conformal symmetry. the gravitational potentials are related explicitly by the conformal vector. we use this relationship between the metric potentials to find new classes of exact solutions to the field equations. we identify a particular model to study the ... | relativistic stars with conformal symmetry |
blobs, or quasi-spherical emission regions containing relativistic particles and magnetic fields, are often assumed ad hoc in emission models of relativistic astrophysical jets, yet their physical origin is still not well understood. here, we employ a suite of large-scale 2d particle-in-cell simulations in electron-pos... | plasmoids in relativistic reconnection, from birth to adulthood: first they grow, then they go |
motivated by the unknown nature of the 2.50 -2.67 m⊙ compact object in the binary merger event gw190814, we study the maximum neutron star mass based on constraints from low-energy nuclear physics, neutron star tidal deformabilities from gw170817, and simultaneous mass-radius measurements of psr j0030+045 from nicer. o... | radius and equation of state constraints from massive neutron stars and gw190814 |
recent observations of fast radio bursts (frbs) indicate a perplexing, inconsistent picture. we propose a unified scenario to interpret diverse frbs observed. a regular pulsar, otherwise unnoticeable at a cosmological distance, may produce a bright frb if its magnetosphere is suddenly “combed” by a nearby, strong plasm... | a “cosmic comb” model of fast radio bursts |
the nature of dark matter remains obscure in spite of decades of experimental efforts. the mass of dark matter candidates can span a wide range, and its coupling with the standard model sector remains uncertain. all these unknowns make the detection of dark matter extremely challenging. ultralight dark matter, with m ∼... | high-precision search for dark photon dark matter with the parkes pulsar timing array |
some models (such as the skyrme model, a low-energy effective field theory for quantum chromodynamics) suggest that the high-density matter prevailing in neutron star (ns) interiors may be significantly anisotropic. anisotropy is known to affect the bulk properties of nonrotating nss in general relativity (gr). in this... | slowly rotating anisotropic neutron stars in general relativity and scalar-tensor theory |
we present a new class of solutions to the einstein field equations for an anisotropic matter distribution in which the interior space-time obeys the karmarkar condition. the necessary and sufficient condition required for a spherically symmetric space-time to be of class one reduces the gravitational behavior of the m... | anisotropic compact stars in karmarkar spacetime |
first discovered in 2007, fast radio bursts (frbs) are highly luminous (10-1-102 jy), millisecond-scale, highly dispersive single radio pulses whose record high brightness temperatures suggest a nonthermal emission mechanism. as of march 2018, a total of 32 frbs have been recorded. there is also one repeating source, f... | fast radio bursts |
qed cascades are complex avalanche processes of hard photon emission and electron-positron pair creation driven by ultrastrong electromagnetic fields. they play a fundamental role in astrophysical environments such as a pulsars' magnetosphere, rendering an earth-based implementation with intense lasers attractive. in t... | laser-pulse-shape control of seeded qed cascades |
pulsar timing arrays seek and study gravitational waves (gws) through the angular two-point correlation function of timing residuals they induce in pulsars. the two-point correlation function induced by the standard transverse-traceless gws is the famous hellings-downs curve, a function only of the angle between the tw... | all the pretty overlap reduction functions |
non-relativistic axions can be efficiently produced in in the polar caps of pulsars, resulting in the formation of a dense cloud of gravitationally bound axions. here, we investigate the interplay between such an axion cloud and the electrodynamics in the pulsar magnetosphere, focusing specifically on the dynamics in t... | pulsar nulling and vacuum radio emission from axion clouds |
the chinese pulsar timing array (cpta) collaboration has recently reported the observational evidence of a stochastic gravitational wave background. in light of the latest cpta observation, we aim at exploring the ability of cpta in probing new physics. specifically, we constrain the first-order cosmological phase tran... | constraining cosmological phase transitions with chinese pulsar timing array data release 1 |
puma is a proposed ultra-wideband low-resolution interferometric transit radio telescope operating at 200-1100 mhz composed of thousands of 6m dishes. it is optimized for intensity mapping of the redshifted 21cm line over z=0.3-6 to study dark energy and inflation. the same design also allows an unprecedented study of ... | packed ultra-wideband mapping array (puma): a radio telescope for cosmology and transients |
the angular correlation of pulsar residuals observed by nanograv and other pulsar timing array (pta) collaborations show evidence in support of the hellings-downs correlation expected from stochastic gravitational waves (sgw). in this paper, we offer a non-gravitational wave explanation of the observed pulsar timing co... | ultralight $(l_\\mu-l_\\tau)$ vector dark matter interpretation of nanograv observations |
we report a revised analysis for the radius, mass, and hot surface regions of the massive millisecond pulsar psr j0740+6620, studied previously with joint fits to nicer and xmm-newton data by riley et al. (2021) and miller et al. (2021). we perform a similar bayesian estimation for the pulse-profile model parameters, e... | the radius of psr j0740+6620 from nicer with nicer background estimates |
using twenty long-term 3d core-collapse supernova simulations, we find that lower compactness progenitors that explode quasi-spherically due to the short delay to explosion experience smaller neutron star recoil kicks in the $\sim$100$-$200 km s$^{-1}$ range, while higher compactness progenitors that explode later and ... | a theory for neutron star and black hole kicks and induced spins |
intermediate-mass black holes should help us to understand the evolutionary connection between stellar-mass and super-massive black holes. however, the existence of intermediate-mass black holes is still uncertain, and their formation process is therefore unknown. it has long been suspected that black holes with masses... | an intermediate-mass black hole in the centre of the globular cluster 47 tucanae |
swift j0243.6+6124 is a newly discovered galactic be/x-ray binary, revealed in late 2017 september in a giant outburst with a peak luminosity of 2 × 1039(d/7 kpc)2 erg s-1 (0.1-10 kev), with no formerly reported activity. at this luminosity, swift j0243.6+6124 is the first known galactic ultraluminous x-ray pulsar. we ... | nicer and fermi gbm observations of the first galactic ultraluminous x-ray pulsar swift j0243.6+6124 |
we analyze plasma dispersion and scattering of fast radio bursts (frbs) to identify the dominant locations of free electrons along their lines of sight and thus constrain the distances of the burst sources themselves. we establish the average $\tau$-dm relation for galactic pulsars and use it as a benchmark for discuss... | radio wave propagation and the provenance of fast radio bursts |
the discovery of extended tev emission around the geminga and psr b0656+14 pulsars, with properties consistent with free particle propagation in the interstellar medium (ism), has led to the suggestion of "tev halos" as a separate source class, which is distinct from pulsar wind nebulae. this has sparked considerable d... | halo fraction in tev-bright pulsar wind nebulae |
pulsar timing array projects measure the pulse arrival times of millisecond pulsars for the primary purpose of detecting nanohertz-frequency gravitational waves. the measurements include contributions from a number of astrophysical and instrumental processes, which can either be deterministic or stochastic. it is neces... | identifying and mitigating noise sources in precision pulsar timing data sets |
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