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because of the development of many-body theories of nuclear matter, the long-standing, open problem of the equation of state (eos) of dense matter may be understood in the near future through the confrontation of theoretical calculations with laboratory measurements of nuclear properties & reactions and increasingl... | neutron star equation of state: quark mean-field (qmf) modeling and applications |
primordial black holes (pbhs) can be produced by the perturbations that exit the horizon during the inflationary phase. while inflation models predict the power spectrum of the perturbations in fourier space, the pbh abundance depends on the probability distribution function of density perturbations in real space. to e... | primordial black holes and uncertainties in the choice of the window function |
the interpretation of pulsar rotational glitches, the sudden increase in spin frequency of neutron stars, is a half-century-old challenge. the common view is that glitches are driven by the dynamics of the stellar interior, and connect in particular to the interactions between a large-scale neutron superfluid and the o... | pulsar glitches: observations and physical interpretation |
we examine the possibility that the light companion in the highly asymmetric binary compact object coalescence event gw190814 is a hypernuclear star. we use density functional theory with functionals that have been tuned to the properties of λ hypernuclei as well as astrophysical constraints placed by the masses of the... | confronting gw190814 with hyperonization in dense matter and hypernuclear compact stars |
current models of gamma-ray light curves in pulsars suffer from large uncertainties on the precise location of particle acceleration and radiation. here, we present an attempt to alleviate these difficulties by solving for the electromagnetic structure of the oblique magnetosphere, particle acceleration, and the emissi... | modelling high-energy pulsar light curves from first principles |
the recently developed resummation technique known as renormalization group optimized perturbation theory (rgopt) is employed in the evaluation of the equation of state (eos) describing nonstrange cold quark matter at next-to leading order. inspired by recent investigations, which suggest that stable quark matter can b... | nonstrange quark stars within resummed qcd |
the 30-hz rotation rate of the crab pulsar has been monitored at jodrell bank observatory since 1984 and by other observatories before then. since 1968, the rotation rate has decreased by about 0.5 hz, interrupted only by sporadic and small spin-up events (glitches). 24 of these events have been observed, including a s... | 45 years of rotation of the crab pulsar |
studies of fermi data indicate an excess of gev gamma rays around the galactic center (gc), possibly due to dark matter. we show that young gamma-ray pulsars can yield a similar signal. first, a high concentration of gc supernovae naturally leads to a population of kicked pulsars symmetric about the gc. second, while v... | young pulsars and the galactic center gev gamma-ray excess |
pulsar timing arrays (ptas) provide a way to detect gravitational waves at nanohertz frequencies. in this band, the most likely signals are stochastic, with a power spectrum that rises steeply at lower frequencies. indeed, the observation of a common red noise process in pulsar-timing data suggests that the first credi... | the international pulsar timing array checklist for the detection of nanohertz gravitational waves |
a repeating source of fast radio bursts (frbs) is recently discovered from a globular cluster of m81. association with a globular cluster (or other old stellar systems) suggests that strongly magnetized neutron stars, which are the most likely objects responsible for frbs, are born not only when young massive stars und... | implications of a rapidly varying frb in a globular cluster of m81 |
supermassive black hole binary systems form in galaxy mergers and reside in galactic nuclei with large and poorly constrained concentrations of gas and stars. these systems emit nanohertz gravitational waves that will be detectable by pulsar timing arrays. here we estimate the properties of the local nanohertz gravitat... | the local nanohertz gravitational-wave landscape from supermassive black hole binaries |
we report the real-time discovery of a fast radio burst (frb 131104) with the parkes radio telescope in a targeted observation of the carina dwarf spheroidal galaxy. the dispersion measure of the burst is 779 cm-3 pc, exceeding predictions for the maximum line-of-sight galactic contribution by a factor of 11. the tempo... | a fast radio burst in the direction of the carina dwarf spheroidal galaxy |
we present “first-principles” relativistic particle-in-cell simulations of the oblique pulsar magnetosphere with pair formation. the magnetosphere starts to form with particles extracted from the surface of the neutron star. these particles are accelerated by surface electric fields and emit photons capable of producin... | ab initio pulsar magnetosphere: three-dimensional particle-in-cell simulations of oblique pulsars |
although fifty years have passed since the discovery of radio pulsars, there is still no satisfactory understanding of how these amazing objects operate. while there has been significant progress in understanding the basic properties of radio pulsars, there is as yet no consensus on key issues, such as the nature of co... | radio pulsars: already fifty years! |
we review the role and properties of hyperons in finite and infinite nuclear systems. in particular, we present different production mechanisms of hypernuclei, as well as several aspects of hypernuclear γ-ray spectroscopy, and the weak decay modes of hypernuclei. then we discuss the construction of hyperon-nucleon and ... | hyperons: the strange ingredients of the nuclear equation of state |
we construct a realistic supersymmetric model for superheavy metastable cosmic strings (css) that can be investigated in the current pulsar timing array (pta) experiments. we consider shifted $\mu$ hybrid inflation in which the symmetry breaking $su(4)_c \times su(2)_l \times u(1)_r\rightarrow su(3)_c\times su(2)_l \ti... | supersymmetric hybrid inflation and metastable cosmic strings in $su(4)_c \\times su(2)_l \\times u(1)_r$ |
we describe how the observed polarization properties of an astronomical object are related to its intrinsic polarization properties and the finite temporal and spectral resolutions of the observing device. moreover, we discuss the effect that a scattering screen, with non-zero magnetic field, between the source and obs... | faraday depolarization and induced circular polarization by multipath propagation with application to frbs |
since fast radio bursts (frbs) were discovered, their precise origins have remained a mystery. multiwavelength observations of nearby frb sources provide one of the best ways to make rapid progress in our understanding of the enigmatic frb phenomenon. we present results from a sensitive, broadband multiwavelength x-ray... | multiwavelength constraints on the origin of a nearby repeating fast radio burst source in a globular cluster |
this paper investigates the concept of cracking and overturning to analyze the impact of local density perturbations on the stability of self-gravitating compact objects in the framework of f (r ,ϕ ,x ) theory of gravity, where r, ϕ , and x denote the ricci scalar, scalar potential, and kinetic term, respectively. in t... | a comprehensive discussion for the identification of cracking points in f(r) theories of gravity |
an anomalous emission component at energies of a few gigaelectronvolts and located towards the inner galaxy is present in the fermi-lat data. at present, the two most promising explanations are the annihilation of dark matter particles or the presence of a large population of unresolved point sources, most probably mil... | the fermi-lat gev excess as a tracer of stellar mass in the galactic bulge |
we perform numerical simulations of gravitational waves (gws) induced by hydrodynamic and hydromagnetic turbulent sources that might have been present at cosmological quantum chromodynamic (qcd) phase transitions. for turbulent energies of about 4% of the radiation energy density, the typical scale of such motions may ... | can we observe the qcd phase transition-generated gravitational waves through pulsar timing arrays? |
we perform a bayesian analysis of the maximum mass mtov of neutron stars with a quark core, incorporating the observational data from tidal deformability of the gw170817 binary neutron star merger as detected by ligo/virgo and the mass and radius of psr j0030+0451 as detected by the neutron star interior composition ex... | constraints on the maximum mass of neutron stars with a quark core from gw170817 and nicer psr j0030+0451 data |
fast radio burst (frb) source frb 20180916b exhibits a 16.33-day periodicity in its burst activity. it is as of yet unclear what proposed mechanism produces the activity, but polarization information is a key diagnostic. here we report on the polarization properties of 44 bursts from frb 20180916b detected between 2018... | a large-scale magneto-ionic fluctuation in the local environment of periodic fast radio burst source frb 20180916b |
we report the properties of more than 800 bursts detected from the repeating fast radio burst (frb) source frb 20201124a with the five-hundred-meter aperture spherical radio telescope (fast) during an extremely active episode on utc 2021 september 25-28 in a series of four papers. in this second paper of the series, we... | fast observations of an extremely active episode of frb 20201124a. ii. energy distribution |
we develop a model of the generation of coherent radio emission in the crab pulsar, magnetars, and fast radio bursts (frbs). emission is produced by a reconnection-generated beam of particles via a variant of the free electron laser mechanism, operating in a weakly turbulent, guide field-dominated plasma. we first cons... | coherent emission in pulsars, magnetars, and fast radio bursts: reconnection-driven free electron laser |
within a confining quark matter model which considers phenomenologically the quark confinement and asymptotic freedom as well as the chiral symmetry restoration and quark deconfinement at high baryon density, we find that if the up-down quark matter (u d qm ) is more stable than nuclear matter and strange quark matter ... | gw190814: circumstantial evidence for up-down quark star |
we investigate the possibility that gw170817 was not the merger of two conventional neutron stars (ns), but involved at least one if not two hybrid stars with a quark matter core that might even belong to a third family of compact stars. to this end, we develop a bayesian analysis method for selecting the most probable... | was gw170817 a canonical neutron star merger? bayesian analysis with a third family of compact stars |
diffusive tev gamma-ray emissions have been recently discovered extending beyond the pulsar wind nebulae of a few middle-aged pulsars, implying that energetic electron/ positron pairs are escaping from the pulsar wind nebulae and radiating in the ambient interstellar medium. it has been suggested that these extended em... | the physics of pulsar halos: research progress and prospect |
gravitational-wave (gw) astronomy is transforming our understanding of the universe by probing phenomena invisible to electromagnetic observatories. a comprehensive exploration of the gw frequency spectrum is essential to fully harness this potential. remarkably, current methods have left the μ hz frequency band almost... | bridging the μ hz gap in the gravitational-wave landscape with binary resonances |
gamma-ray data from the fermi large area telescope reveal an unexplained, apparently diffuse, signal from the galactic bulge1-3 that peaks near ~2 gev with an approximately spherical4 intensity profile ∝ r−2.4 (refs. 3,5), where r is the radial distance to the galactic centre, that extends to angular radial scales of a... | millisecond pulsars from accretion-induced collapse as the origin of the galactic centre gamma-ray excess signal |
in this work we study static neutron stars in the context of several inflationary models which are popular in cosmology. these inflationary models are nonminimally coupled scalar theories which yield a viable inflationary phenomenology in both jordan and einstein frames. by considering the constraints from inflationary... | inflationary attractors predictions for static neutron stars in the mass-gap region |
screened modified gravity (smg) is a kind of scalar-tensor theory with screening mechanisms, which can suppress the fifth force in dense regions and allow theories to evade the solar system and laboratory tests. in this paper, we investigate how the screening mechanisms in smg affect the gravitational radiation damping... | gravitational radiation from compact binary systems in screened modified gravity |
the hawc collaboration has discovered a γ -ray emission extended about 2 degrees around the geminga and monogem pulsar wind nebulae (pwne) at γ -ray energies eγ>5 tev . we analyze, for the first time, almost 10 years of γ -ray data obtained with the fermi large area telescope at eγ>8 gev in the direction of gemin... | detection of a γ -ray halo around geminga with the fermi-lat data and implications for the positron flux |
we present the first optical spectroscopy of five confirmed (or strong candidate) redback millisecond pulsar binaries, obtaining complete radial velocity curves for each companion star. the properties of these millisecond pulsar binaries with low-mass, hydrogen-rich companions are discussed in the context of the 14 con... | optical spectroscopy and demographics of redback millisecond pulsar binaries |
meertime is a five-year large survey project to time pulsars with meerkat, the 64-dish south african precursor to the square kilometre array. the science goals for the programme include timing millisecond pulsar (msps) to high precision ( <1 μs ) to study the galactic msp population and to contribute to global effor... | the meertime pulsar timing array: a census of emission properties and timing potential |
binary pulsar observations and gravitational wave detections seriously constrained scalar-tensor theories with massless scalar field allowing only small deviations from general relativity. if we consider a nonzero mass of the scalar field, though, significant deviations from general relativity are allowed for values of... | static and slowly rotating neutron stars in scalar-tensor theory with self-interacting massive scalar field |
in this white paper we present the potential of the enhanced x-ray timing and polarimetry (extp) mission for determining the nature of dense matter; neutron star cores host an extreme density regime which cannot be replicated in a terrestrial laboratory. the tightest statistical constraints on the dense matter equation... | dense matter with extp |
fast radio bursts (frbs) are short pulses observed in radio frequencies usually originating from cosmological distances. the discovery of frb 200428 and its x-ray counterpart from the galactic magnetar sgr j1935+2154 suggests that at least some frbs can be generated by magnetars. however, the majority of x-ray bursts f... | a giant glitch from the magnetar sgr j1935+2154 before frb 200428 |
in this contribution, we discuss the cosmological scenario where unstable domain walls are formed in the early universe and their late-time annihilation produces a significant amount of gravitational waves. after describing cosmological constraints on long-lived domain walls, we estimate the typical amplitude and frequ... | a review of gravitational waves from cosmic domain walls |
in this paper, we attempt to investigate the nature of the first gravitational wave (gw) signal to be detected by pulsar timing arrays (ptas): will it be an individual, resolved supermassive black hole binary (sbhb), or a stochastic background made by the superposition of gws produced by an ensemble of sbhbs? to addres... | expected properties of the first gravitational wave signal detected with pulsar timing arrays |
the accretion flow around x-ray pulsars with a strong magnetic field is funnelled by the field to relatively small regions close to the magnetic poles of the neutron star (ns), the hotspots. during strong outbursts regularly observed from some x-ray pulsars, the x-ray luminosity can be so high that the emerging radiati... | the critical accretion luminosity for magnetized neutron stars |
gaseous circumbinary accretion discs provide a promising mechanism to facilitate the mergers of supermassive black holes (smbhs) in galactic nuclei. we measure the torques exerted on accreting smbh binaries, using 2d, isothermal, moving-mesh, viscous hydrodynamical simulations of circumbinary accretion discs. our compu... | on the orbital evolution of supermassive black hole binaries with circumbinary accretion discs |
as pulsars lose energy, primarily in the form of magnetic dipole radiation, their rotation slows down accordingly. for some pulsars, this spin-down is interrupted by occasional abrupt spin-up events known as glitches1. a glitch is hypothesized to be a catastrophic release of pinned vorticity2 that provides an exchange ... | alteration of the magnetosphere of the vela pulsar during a glitch |
in this work, a physically reasonable metric potential grr and a specific choice of the anisotropy has been utilized to obtain closed-form solutions of the einstein field equation for a spherically symmetric anisotropic matter distribution. this class of solution has been used to develop viable models for observed puls... | a new class of compact stellar model compatible with observational data |
over the past 13 yr, the parkes radio telescope has observed a large number of pulsars using digital filter bank backends with high time and frequency resolution and the capability for stokes recording. here, we use archival data to present polarimetry data at an observing frequency of 1.4 ghz for 600 pulsars with spin... | polarimetry of 600 pulsars from observations at 1.4 ghz with the parkes radio telescope |
the equatorial current sheet in pulsar magnetospheres is often regarded as an ideal site for particle acceleration via relativistic reconnection. using 2d spherical particle-in-cell simulations, we investigate particle acceleration in the axisymmetric pulsar magnetosphere as a function of the injected plasma multiplici... | particle acceleration in axisymmetric pulsar current sheets |
future searches for gravitational waves from space will be sensitive to double compact objects in our milky way. we present new simulations of the populations of double black holes (bhbhs), bh neutron stars (bhnss), and double neutron stars (nsnss) that will be detectable by the planned space-based gravitational-wave d... | gravitational wave sources in our galactic backyard: predictions for bhbh, bhns, and nsns binaries detectable with lisa |
we present here the first convincing observational manifestation of a magnetar-like magnetic field in an accreting neutron star in binary system - the first pulsating ultraluminous x-ray source x-2 in the galaxy m82. using the chandra x-ray observatory data, we show that the source exhibit the bimodal distribution of t... | propeller effect in action in the ultraluminous accreting magnetar m82 x-2 |
ultraluminous pulsars are a definite proof that persistent super-eddington accretion occurs in nature. they support the scenario according to which most ultraluminous x-ray sources (ulxs) are super-eddington accretors of stellar mass rather than sub-eddington intermediate mass black holes. an important prediction of th... | evidence for a variable ultrafast outflow in the newly discovered ultraluminous pulsar ngc 300 ulx-1 |
the fast radio burst frb121102 has been observed to repeat in an irregular fashion. using published timing data of the observed bursts, we show that poissonian statistics are not a good description of this random process. as an alternative, we suggest to describe the intervals between bursts with a weibull distribution... | on the non-poissonian repetition pattern of frb121102 |
pulsar glitches are rapid spin-up events that occur in the rotation of neutron stars, providing a valuable probe into the physics of the interiors of these objects. long-term monitoring of a large number of pulsars facilitates the detection of glitches and the robust measurements of their parameters. the jodrell bank p... | the jodrell bank glitch catalogue: 106 new rotational glitches in 70 pulsars |
we review primordial black hole (pbh) formation in the axionlike curvaton model and investigate whether pbhs formed in this model can be the origin of the gravtitational wave (gw) signals detected by the advanced ligo. in this model, small-scale curvature perturbations with large amplitude are generated, which is essen... | primordial black holes for the ligo events in the axionlike curvaton model |
we discuss possible association of fast radio bursts (frbs) with supergiant pulses emitted by young pulsars (ages ∼ tens to hundreds of years) born with regular magnetic field but very short - few milliseconds - spin periods. we assume that frbs are extra-galactic events coming from distances d ≲ 100 mpc and that most ... | fast radio bursts as giant pulses from young rapidly rotating pulsars |
we update the ephemeris of the eclipsing high-mass x-ray binary (hmxb) systems lmc x-4, cen x-3, 4u 1700-377, 4u 1538-522, smc x-1, igr j18027-2016, vela x-1,igr j17252-3616, xte j1855-026, and oao 1657-415 with the help of more than ten years of monitoring these sources with the all sky monitor onboard rxte and with t... | ephemeris, orbital decay, and masses of ten eclipsing high-mass x-ray binaries |
binary interactions lead to the formation of intriguing objects, such as compact binaries, supernovae, gamma ray bursts, x-ray binaries, pulsars, novae, cataclysmic variables, hot subdwarf stars, barium stars and blue stragglers. to study the evolution of binary populations and the consequent formation of these objects... | binary population synthesis |
metastable cosmic strings appear in models of new physics with a two-step symmetry breaking $g\to h\to 1$, where $\pi_1(h)\neq 0$ and $\pi_1(g)=0$. they decay via the monopole-antimonopole pair creation inside. conventionally, the breaking rate has been estimated by an infinitely thin string approximation, which requir... | revisiting metastable cosmic string breaking |
we search nanograv's 12.5 yr data set for evidence of a gravitational-wave background (gwb) with all the spatial correlations allowed by general metric theories of gravity. we find no substantial evidence in favor of the existence of such correlations in our data. we find that scalar-transverse (st) correlations yield ... | the nanograv 12.5-year data set: search for non-einsteinian polarization modes in the gravitational-wave background |
the maximum mass of a non-rotating neutron star, mtov, plays a very important role in deciphering the structure and composition of neutron stars and in revealing the equation of state (eos) of nuclear matter. although with a large-error bar, the recent mass estimate for the black-widow binary pulsar psr j0952-0607, i.e... | impact of large-mass constraints on the properties of neutron stars |
the puzzling mechanism of coherent radio emission remains unknown, but fortunately, repeating fast radio bursts (frbs) provide a precious opportunity, with extremely bright subpulses created in a clear and vacuum-like pulsar magnetosphere. frbs are millisecond-duration signals that are highly dispersed at distant galax... | repeating frbs reveal the secret of pulsar magnetospheric activity |
dark photon dark matter may be produced by the cosmic strings in association with the dark u(1) gauge symmetry breaking. we perform three-dimensional lattice simulations of the abelian-higgs model and follow the evolution of cosmic strings. in particular, we simulate the case of (very) light vector boson and find that ... | dark photon dark matter from cosmic strings and gravitational wave background |
pulsar timing arrays (ptas) are sensitive to oscillations in the gravitational potential along the line-of-sight due to ultralight particle pressure. we calculate the probing power of ptas for ultralight bosons across all frequencies, from those larger than the inverse observation time to those smaller than the inverse... | probing ultralight scalar, vector and tensor dark matter with pulsar timing arrays |
using observations of x-ray pulsar hercules x-1 by the imaging x-ray polarimetry explorer we report a highly significant (>17σ) detection of the polarization signal from an accreting neutron star. the observed degree of linear polarization of ~10% is far below theoretical expectations for this object, and stays low ... | determination of x-ray pulsar geometry with ixpe polarimetry |
pulsar timing arrays have found evidence for a low-frequency gravitational wave background (gwb). assuming the gwb is produced by supermassive black hole binaries (smbhbs), the next gravitational wave (gw) signals astronomers anticipate are continuous waves (cws) from single smbhbs and their associated gwb anisotropy. ... | beyond the background: gravitational wave anisotropy and continuous waves from supermassive black hole binaries |
context. recently, doroshenko and collaborators reported a very low-mass compact star, a central compact object named xmmu j173203.3−344518 inside the supernova remnant hess j1731−347. its tiny mass is at odds with all calculations of minimum masses of neutron stars generated by iron cores, therefore (and even if not c... | a light strange star in the remnant hess j1731−347: minimal consistency checks |
the european pulsar timing array (epta) collaboration has recently released an extended data set for six pulsars (dr2) and reported evidence for a common red noise signal. here we present a noise analysis for each of the six pulsars. we consider several types of noise: (i) radio frequency independent, 'achromatic', and... | noise analysis in the european pulsar timing array data release 2 and its implications on the gravitational-wave background search |
the recent compelling observation of the nanohertz stochastic gravitational wave background has brought to light a new galactic arena to test gravity. in this paper, we derive a formula for the most general expression of the stochastic gravitational wave background correlation that could be tested with pulsar timing an... | correlations for an anisotropic polarized stochastic gravitational wave background in pulsar timing arrays |
we explore the inflationary dynamics leading to formation of closed domain walls in course of evolution of an axion like particle (alp) field whose peccei-quinn-like phase transition occurred well before inflationary epoch. evolving after inflation, the domain walls may leave their imprint in stochastic gravitational w... | looking at the nanograv signal through the anthropic window of axionlike particles |
we derive a new interior solution for stellar compact objects in f (r ) gravity assuming a differential relation to constrain the ricci curvature scalar. to this aim, we consider specific forms for the radial component of the metric and the first derivative of f (r ) . after, the time component of the metric potential ... | anisotropic compact stars in f(r) gravity |
symmetries play a fundamental role in modern theories of gravity. the strong equivalence principle (sep) constitutes a collection of gravitational symmetries which are all implemented by general relativity. alternative theories, however, are generally expected to violate some aspects of sep. we test three aspects of se... | tests of gravitational symmetries with pulsar binary j1713+0747 |
we present three-dimensional (3d) global kinetic pulsar magnetosphere models, where the charged particle trajectories and the corresponding electromagnetic fields are treated self-consistently. for our study, we have developed a cartesian 3d relativistic particle-in-cell code that incorporates radiation reaction forces... | three-dimensional kinetic pulsar magnetosphere models: connecting to gamma-ray observations |
we report on a timing programme of 74 young pulsars that have been observed by the parkes 64-m radio telescope over the past decade. using modern bayesian timing techniques, we have measured the properties of 124 glitches in 52 of these pulsars, of which 74 are new. we demonstrate that the glitch sample is complete to ... | the impact of glitches on young pulsar rotational evolution |
ultra-low-frequency gravitational waves (gws) generated by individual inspiraling supermassive black hole binaries (smbhbs) in the centers of galaxies may be detected by pulsar timing arrays (ptas) in the future. these gw signals encoding absolute cosmic distances can serve as bright and dark sirens, having potential t... | ultra-low-frequency gravitational waves from individual supermassive black hole binaries as standard sirens |
it is widely accepted that dark matter contributes about a quarter of the critical mass-energy density in our universe. the nature of dark matter is currently unknown, with the mass of possible constituents spanning nearly one hundred orders of magnitude. the ultralight scalar field dark matter, consisting of extremely... | parkes pulsar timing array constraints on ultralight scalar-field dark matter |
the fermi satellite has recently detected gamma-ray emission from the central regions of our galaxy. this may be evidence for dark matter particles, a major component of the standard cosmological model, annihilating to produce high-energy photons. we show that the observed signal may instead be generated by millisecond... | disrupted globular clusters can explain the galactic center gamma-ray excess |
we study the radio signals generated when an axion star enters the magnetosphere of a neutron star. as the axion star moves through the resonant region where the plasma-induced photon mass becomes equal to the axion mass, the axions can efficiently convert into photons, giving rise to an intense, transient radio signal... | fast radio bursts from axion stars moving through pulsar magnetospheres |
models of dark matter (dm) can leave unique imprints on the universe's small scale structure by boosting density perturbations on small scales. we study the capability of pulsar timing arrays to search for, and constrain, subhalos from such models. the models of dm we consider are ordinary adiabatic perturbations in λc... | probing small-scale power spectra with pulsar timing arrays |
milagro and the high altitude water cherenkov (hawc) observatory have detected extended tev gamma-ray emission around nearby pulsar wind nebulae. building on these discoveries, t. linden et al., phys. rev. d 96, 103016 (2017)., 10.1103/physrevd.96.103016 identified a new source class—tev halos—powered by the interactio... | tev halos are everywhere: prospects for new discoveries |
we have recently shown that axions and axionlike particles (alps) may emit an observable stochastic gravitational wave (gw) background when they begin to oscillate in the early universe. in this note, we identify the regions of alp parameter space, which may be probed by future gw detectors, including ground- and space... | gravitational wave probes of axionlike particles |
as the third paper in the multiple-part series, we report the statistical properties of radio bursts detected from the repeating fast radio burst (frb) source frb 20201124a with the five-hundred-meter aperture spherical radio telescope during an extremely active episode between the 25th and 28th of september 2021 (ut).... | fast observations of an extremely active episode of frb 20201124a. iii. polarimetry |
we present the discovery of psr j0250+5854, a radio pulsar with a spin period of 23.5 s. this is the slowest-spinning radio pulsar known. psr j0250+5854 was discovered by the lofar tied-array all-sky survey (lotaas), an all-northern-sky survey for pulsars and fast transients at a central observing frequency of 135 mhz.... | lofar discovery of a 23.5 s radio pulsar |
the hypernuclear matter is studied within the relativistic hartree-fock theory employing several parametrizations of the hypernuclear density functional with density-dependent couplings. the equations of state and compositions of hypernuclear matter are determined for each parametrization and compact stars are construc... | hypernuclear stars from relativistic hartree-fock density functional theory |
close double neutron stars (dnss) have been observed as galactic radio pulsars, while their mergers have been detected as gamma-ray bursts and gravitational wave sources. they are believed to have experienced at least one common envelope episode (cee) during their evolution prior to dns formation. in the last decades, ... | common envelope episodes that lead to double neutron star formation |
pulsars are factories of relativistic electrons and positrons that propagate away from the pulsar, eventually permeating our galaxy. the acceleration and propagation of these cosmic particles are a matter of intense debate. in the last few years, we have had the opportunity to directly observe the injection of these pa... | gamma-ray haloes around pulsars as the key to understanding cosmic-ray transport in the galaxy |
general relativity has been widely tested in weak gravitational fields but still stands largely untested in the strong-field regime. according to the no-hair theorem, black holes in general relativity depend only on their masses and spins and are described by the kerr metric. mass and spin are the first two multipole m... | sgr a* and general relativity |
much of the parameter space relevant to the evolution of astrophysical circumbinary accretion discs remains unexplored. we have carried out a suite of circumbinary disc simulations surveying both disc thickness and kinematic viscosity, using both constant-ν and constant-α prescriptions. we focus primarily on disc aspec... | a survey of disc thickness and viscosity in circumbinary accretion: binary evolution, variability, and disc morphology |
dense nuclear matter is expected to be anisotropic due to effects such as solidification, superfluidity, strong magnetic fields, hyperons, pion-condensation. therefore an anisotropic neutron star core seems more realistic than an ideally isotropic one. we model anisotropic neutron stars working in the krori-barua (kb) ... | anisotropic neutron stars modelling: constraints in krori-barua spacetime |
background: the recent accurate measurement of the mass of two pulsars close to or above 2 m⊙ has raised the question of whether such large pulsar masses allow for the existence of exotic degrees of freedom, such as hyperons, inside neutron stars. purpose: in the present work, we will investigate, within a phenomenolog... | hypernuclei and massive neutron stars |
neutron stars are excellent emitters of gravitational waves. squeezing matter beyond nuclear densities invites exotic physical processes, many of which violently transfer large amounts of mass at relativistic velocities, disrupting spacetime and generating copious quantities of gravitational radiation. i review mechani... | gravitational waves from neutron stars: a review |
the stochastic gravitational-wave background is imprinted on the times of arrival of radio pulses from millisecond pulsars. traditional pulsar timing analyses fit a timing model to each pulsar and search the residuals of the fit for a stationary time correlation. this method breaks down at gravitational-wave frequencie... | searching for stochastic gravitational waves below a nanohertz |
recent observations have detected extended tev γ -ray emission surrounding young and middle-aged pulsars. the morphology of these "tev halos" requires cosmic-ray diffusion to be locally suppressed by a factor of ∼100 - 1000 compared to the typical interstellar medium. no model currently explains this suppression. we sh... | self-generated cosmic-ray confinement in tev halos: implications for tev γ -ray emission and the positron excess |
rapidly spinning neutron stars are promising sources of continuous gravitational waves. detecting such a signal would allow probing of the physical properties of matter under extreme conditions. a significant fraction of the known pulsar population belongs to binary systems. searching for unknown neutron stars in binar... | all-sky search in early o3 ligo data for continuous gravitational-wave signals from unknown neutron stars in binary systems |
we investigate remnant neutron star masses (in particular, the minimum allowed mass) by performing advanced stellar evolution calculations and neutrino-radiation hydrodynamics simulations for core-collapse supernova explosions. we find that, based on standard astrophysical scenarios, low-mass carbon-oxygen cores can ha... | on the minimum mass of neutron stars |
the ligo/virgo collaborations recently announced the detection of a binary neutron star merger, gw190425. the mass of gw190425 is significantly larger than the masses of galactic double neutron stars known through radio astronomy. we hypothesize that gw190425 formed differently from galactic double neutron stars, via u... | on the origin of gw190425 |
the `magnificent seven' (m7) are a group of radio-quiet isolated neutron stars discovered in the soft x-rays through their purely thermal surface emission. owing to the large inferred magnetic fields (b ≈ 1013 g), radiation from these sources is expected to be substantially polarized, independently of the mechanism act... | evidence for vacuum birefringence from the first optical-polarimetry measurement of the isolated neutron star rx j1856.5-3754 |
the matter state inside neutron stars (nss) is an exciting problem in astrophysics, nuclear physics, and particle physics. the equation of state (eos) of nss plays a crucial role in the present multimessenger astronomy, especially after the event of gw170817. we propose a new ns eos, “qmf18,” from the quark level, whic... | neutron star equation of state from the quark level in light of gw170817 |
the smooth spin-down of young pulsars is perturbed by two non-deterministic phenomenon, glitches, and timing noise. although the timing noise provides insights into nuclear and plasma physics at extreme densities, it acts as a barrier to high-precision pulsar timing experiments. an improved methodology based on the bay... | timing of young radio pulsars - i. timing noise, periodic modulation, and proper motion |
the black hole in the center of the milky way, sgr a*, has the largest mass-to-distance ratio among all known black holes in the universe. this property makes sgr a* the optimal target for testing the gravitational no-hair theorem. in the near future, major developments in instrumentation will provide the tools for hig... | a quantitative test of the no-hair theorem with sgr a* using stars, pulsars, and the event horizon telescope |
the main goal of pulsar timing array experiments is to detect correlated signals such as nanohertz-frequency gravitational waves. pulsar timing data collected in dense monitoring campaigns can also be used to study the stars themselves, their binary companions, and the intervening ionized interstellar medium. timing ob... | the parkes pulsar timing array second data release: timing analysis |
axions are well-motivated candidates for dark matter. recently, much interest has focused on the detection of photons produced by the resonant conversion of axion dark matter in neutron star magnetospheres. various groups have begun to obtain radio data to search for the signal, however, more work is needed to obtain a... | radio line properties of axion dark matter conversion in neutron stars |
spectra of stochastic gravitational waves (gw) generated in cosmological first-order phase transitions are computed within strongly correlated theories with a dual holographic description. the theories are mostly used as models of dark sectors. in particular, we consider the so-called witten-sakai-sugimoto model, a su(... | dark holograms and gravitational waves |
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