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as a fundamental process converting magnetic to plasma energy in high-energy astrophysical plasmas, relativistic magnetic reconnection is a leading explanation for the acceleration of particles to the ultrarelativistic energies that are necessary to power nonthermal emission (especially x-rays and gamma-rays) in pulsar... | nonthermal particle acceleration in 3d relativistic magnetic reconnection in pair plasma |
in the framework of teleparallel gravity, we derive a charged non-vacuum solution for a physically symmetric tetrad field with two unknown functions of radial coordinate. the field equations result in a closed-form adopting particular metric potentials and a suitable anisotropy function combined with the charge. under ... | stable and self-consistent compact star models in teleparallel gravity |
observations by hawc and milagro have detected bright and spatially extended tev γ -ray sources surrounding the geminga and monogem pulsars. we argue that these observations, along with a substantial population of other extended tev sources coincident with pulsar wind nebulae, constitute a new morphological class of sp... | using hawc to discover invisible pulsars |
the fundamental strong interaction determines the nature of pulsar-like compact stars which are essentially in the form of bulk strong matter. from an observational point of view, it is proposed that bulk strong matter could be composed of strangeons, i.e. quark-clusters with three-light-flavor symmetry of quarks, and ... | strangeons constitute bulk strong matter: test using gw 170817 |
observations of the γ-ray emission around star clusters, isolated supernova remnants, and pulsar wind nebulae indicate that the cosmic-ray (cr) diffusion coefficient near acceleration sites can be suppressed by a large factor compared to the galaxy average. we explore the effects of such local suppression of cr diffusi... | cosmic-ray diffusion suppression in star-forming regions inhibits clump formation in gas-rich galaxies |
we investigate the nonrotating neutron stars in f(t) gravity with f (t ) =t +α t2 , where t is the torsion scalar in the teleparallel formalism of gravity. in particular, we utilize the sly and bsk family of equations of state for perfect fluid to describe the neutron stellar matter and search for the effects of the f(... | realistic neutron star models in f(t) gravity |
this review focuses on applications of the ideas of superfluidity and superconductivity in neutron stars in a broader context, ranging from the microphysics of pairing in nucleonic superfluids to macroscopic manifestations of superfluidity in pulsars. the exposition of the basics of pairing, vorticity and mutual fricti... | superfluidity and superconductivity in neutron stars |
the merger of a neutron star (ns) binary may result in the formation of a long-lived, or indefinitely stable, millisecond magnetar remnant surrounded by a low-mass ejecta shell. a portion of the magnetar’s prodigious rotational energy is deposited behind the ejecta in a pulsar wind nebula, powering luminous optical/x-r... | high-energy neutrinos from millisecond magnetars formed from the merger of binary neutron stars |
current prescriptions for supernova natal kicks in rapid binary population synthesis simulations are based on fits of simple functions to single pulsar velocity data. we explore a new parametrization of natal kicks received by neutron stars in isolated and binary systems developed by mandel & müller, which is based... | calibration of neutron star natal kick velocities to isolated pulsar observations |
we consider the scenario where dark matter (dm) is represented by an ultralight classical scalar field performing coherent periodic oscillations. we point out that such dm perturbs the dynamics of binary systems either through its gravitational field or via direct coupling to ordinary matter. this perturbation gets res... | ultralight dark matter resonates with binary pulsars |
by directly inverting several neutron star (ns) observables in the three-dimensional parameter space for the equation of state of super-dense neutron-rich nuclear matter, we show that the lower radius limit for psr j0740+6620 of mass 2.08 ± 0.07 m⊙ from neutron star interior composition explorer (nicer)'s very recent o... | impact of nicer's radius measurement of psr j0740+6620 on nuclear symmetry energy at suprasaturation densities |
we investigate interacting quark matter (iqm), including the perturbative qcd correction and color superconductivity, for both up-down quark matter and strange quark matter. we first derive an equation of state (eos) unifying all cases by a simple reparametrization and rescaling, through which we manage to maximally re... | unified interacting quark matter and its astrophysical implications |
we investigate the impact of coleman-weinberg inflation on the stochastic gravity wave background spectrum emitted by intermediate-scale cosmic strings. the string network is partially inflated and reenters the horizon at later times after the end of inflation, such that the short string loops are not produced. this le... | cosmic strings, inflation, and gravity waves |
the oscillation of neutron n into mirror neutron n', its mass degenerate partner from dark mirror sector, can gradually transform the neutron stars into the mixed stars consisting in part of mirror dark matter. in quark stars n -n' transitions are suppressed. we study the structure of mixed stars and derive the mass-ra... | neutron-mirror neutron mixing and neutron stars |
the origins of matter and radiation in the universe lie in a hot big bang. we present a number of well-motivated cosmologies in which the big bang occurs through a strong first-order phase transition—either at the end of inflation, after a period of kination ("kination-induced big bang"), or after a second period of va... | have pulsar timing arrays detected the hot big bang: gravitational waves from strong first order phase transitions in the early universe |
the estimation of p- to s-wave velocity ratio (psr) in the subsurface has many applications in gas-bearing reservoir prospecting, lithology discrimination, and anomalous pore-pressure prediction. conventionally, it is estimated with the p- and s-wave velocities/moduli/impedances that are directly obtained from prestack... | amplitude-variation-with-offset inversion using p- to s-wave velocity ratio and p-wave velocity |
in this article we try to present spherically symmetric isotropic strange star model under the framework of f(r,script t) theory of gravity. to this end, we consider that the lagrangian density is a linear function of the ricci scalar r and the trace of the energy momentum tensor script t given as f(r,script t)=r+2χ sc... | strange stars in f(r,script t) gravity |
this review discusses the physics of magnetic reconnection—a process in which the magnetic field topology changes and magnetic energy is converted to kinetic energy—in pair plasmas in the relativistic regime. we focus on recent progress in the field driven by theory advances and the maturity of particle-in-cell codes. ... | relativistic magnetic reconnection in pair plasmas and its astrophysical applications |
we estimate the properties of the double neutron star (dns) population that will be observable by the planned space-based interferometer laser interferometer space antenna (lisa). by following the gravitational radiation-driven evolution of dnss generated from rapid population synthesis of massive binary stars, we esti... | detecting double neutron stars with lisa |
gravitational waves at ultra-low frequencies (≲100 nhz) are key to understanding the assembly and evolution of astrophysical black hole binaries with masses ~106-109 m⊙ at low redshifts1-3. these gravitational waves also offer a unique window into a wide variety of cosmological processes4-11. pulsar timing arrays12-14 ... | ultra-low-frequency gravitational waves from cosmological and astrophysical processes |
it has been proposed that a recent outburst of cosmic-ray electrons could account for the excess of gev-scale gamma rays observed from the region surrounding the galactic center. after studying this possibility in some detail, we identify scenarios in which a series of leptonic cosmic-ray outbursts could plausibly gene... | the galactic center gev excess from a series of leptonic cosmic-ray outbursts |
hundreds of millions of supermassive black hole binaries are expected to contribute to the gravitational-wave signal in the nanohertz frequency band. their signal is often approximated either as an isotropic gaussian stochastic background with a power-law spectrum or as an individual source corresponding to the brighte... | exploring realistic nanohertz gravitational-wave backgrounds |
the recent hawc observations of a very-high-energy γ-ray halo around geminga and monogem indicate a very slow diffusion of cosmic rays that results in a tiny contribution of positrons from these two pulsars to the local flux. this makes the cosmic positron excess anomaly observed by pamela and ams-02 even more puzzling... | two-zone diffusion of electrons and positrons from geminga explains the positron anomaly |
the dispersion measure (dm) is one of the key attributes of radio pulsars and fast radio bursts (frbs). there is a mistaken view that the dm is an accurate measure of the column density of electrons between the observer and the source. to start with, the dm, unlike a true column density, is not a lorentz invariant. nex... | dispersion measure: confusion, constants & clarity |
we present a search for optical bursts from the repeating fast radio burst frb 121102 using simultaneous observations with the high-speed optical camera ultraspec on the 2.4-m thai national telescope and radio observations with the 100-m effelsberg radio telescope. a total of 13 radio bursts were detected, but we found... | a search for optical bursts from the repeating fast radio burst frb 121102 |
pulsar timing arrays (ptas) are exceptionally sensitive detectors in the frequency band nhz ≲f ≲μ hz . ultralight dark matter (uldm), with mass in the range 10-23 ev ≲mϕ≲10-20 ev , is one class of dm models known to generate signals in this frequency window. while purely gravitational signatures of uldm have been studi... | constraining fundamental constant variations from ultralight dark matter with pulsar timing arrays |
we report on the discovery of a new member of the magnetar class, sgr j1935+2154, and on its timing and spectral properties measured by an extensive observational campaign carried out between 2014 july and 2015 march with chandra and xmm-newton (11 pointings). we discovered the spin period of sgr j1935+2154 through the... | the discovery, monitoring and environment of sgr j1935+2154 |
the gravitational waves measured at ligo are presumed here to come from merging primordial black holes. we ask how these primordial black holes could arise through inflationary models while not conflicting with current experiments. among the approaches that work, we investigate the opportunity for corroboration through... | inflationary theory and pulsar timing investigations of primordial black holes and gravitational waves |
the aim of this paper is to generalize the definition of complexity for the static self-gravitating structure in f (r, t, q) gravitational theory, where r is the ricci scalar, t is the trace part of energy-momentum tensor, and q ≡ rαβt αβ. in this context, we have considered locally anisotropic spherical matter distrib... | influence of modification of gravity on the complexity factor of static spherical structures |
aims: we report a new microscopic equation of state (eos) of dense symmetric nuclear matter, pure neutron matter, and asymmetric and β-stable nuclear matter at zero temperature using recent realistic two-body and three-body nuclear interactions derived in the framework of chiral perturbation theory (chpt) and including... | equation of state of dense nuclear matter and neutron star structure from nuclear chiral interactions |
recent tev observations of nearby pulsars with the hawc telescope have been interpreted as evidence that the diffusion of high-energy electrons and positrons within pulsar wind nebulae is highly inefficient compared to the rest of the interstellar medium. if the diffusion coefficient well outside the nebula is close to... | lessons from hawc pulsar wind nebulae observations: the diffusion constant is not a constant; pulsars remain the likeliest sources of the anomalous positron fraction; cosmic rays are trapped for long periods of time in pockets of inefficient diffusion |
we present a phase-coherent timing solution for psr j1640-4631, a young 206 ms pulsar using x-ray timing observations taken with nustar. over this timing campaign, we have measured the braking index of psr j1640-4631 to be n = 3.15 ± 0.03. using a series of simulations, we argue that this unusually high braking index i... | a high braking index for a pulsar |
several groups of authors have analyzed fermi lat data in a region around the galactic center finding an unaccounted gamma-ray excess over diffuse backgrounds in the gev energy range. it has been argued that it is difficult or even impossible to explain this diffuse emission by the leading astrophysical candidates-mill... | millisecond pulsars and the galactic center gamma-ray excess: the importance of luminosity function and secondary emission |
recently, a fully covariant version of the theory of f (t ) torsion gravity has been introduced by m. kršśák and e. saridakis [classical quantum gravity 33, 115009 (2016)]. in covariant f (t ) gravity, the schwarzschild solution is not a vacuum solution for f (t )≠t , and therefore determining the spherically symmetric... | spherically symmetric vacuum in covariant f (t )=t +α/2 t2+o (tγ) gravity theory |
magnetized neutron stars power at least some ultraluminous x-ray sources. the accretion flow in these cases is interrupted at the magnetospheric radius and then reaches the surface of a neutron star following magnetic field lines. accreting matter moving along magnetic field lines forms the accretion envelope around th... | optically thick envelopes around ulxs powered by accreating neutron stars |
context. the recently claimed discovery of a massive (mbh = 68-13+11 m⊙) black hole in the galactic solar neighborhood has led to controversial discussions because it severely challenges our current view of stellar evolution.aims: a crucial aspect for the determination of the mass of the unseen black hole is the precis... | a stripped helium star in the potential black hole binary lb-1 |
we present the first nonlinear lattice simulation of an axion field coupled to a u(1) gauge field during inflation. we use it to fully characterize the statistics of the primordial curvature perturbation ζ . we find high-order statistics to be essential in describing non-gaussianity of ζ in the linear regime of the the... | lattice simulations of axion-u(1) inflation |
context. repeating fast radio bursts (frbs) present excellent opportunities to identify frb progenitors and host environments as well as to decipher the underlying emission mechanism. detailed studies of repeating frbs might also hold clues as to the origin of frbs as a population.aims: we aim to detect bursts from the... | repeating fast radio bursts with wsrt/apertif |
gravitational waves in the sensitivity band of ground-based detectors can be emitted by a number of astrophysical sources, including not only binary coalescences, but also individual spinning neutron stars. the most promising signals from such sources, although not yet detected, are long-lasting, quasi-monochromatic co... | pyfstat: a python package for continuous gravitational-wave data analysis |
we provide a systematic study of hybrid neutron star equations of state (eos) consisting of a relativistic density functional for the hadronic phase and a covariant nonlocal nambu--jona-lasinio (nlnjl) model to describe the color superconducting quark matter phase. changing the values of the two free parameters, the di... | constraining free parameters of a color superconducting non-local nambu-jona-lasinio model using bayesian analysis of neutron stars mass and radius measurements |
we study the prospects for the detection of continuous gravitational signals from normal galactic neutron stars, i.e., nonrecycled stars. we use a synthetic population generated by evolving stellar remnants in time, according to several models. we consider the most recent constraints set by all-sky searches for continu... | continuous gravitational waves from galactic neutron stars: demography, detectability, and prospects |
the nature of the fermi γ -ray galactic center excess (gce) has remained a persistent mystery for over a decade. although the excess is broadly compatible with emission expected due to dark matter annihilation, an explanation in terms of a population of unresolved astrophysical point sources, e.g., millisecond pulsars,... | neural simulation-based inference approach for characterizing the galactic center γ -ray excess |
the low-mass companions of evaporating binary pulsars (black widows and similar) are strongly heated on the side facing the pulsar. however, in high-quality photometric and spectroscopic data, the heating pattern does not match that expected for direct pulsar illumination. here we explore a model where the pulsar power... | intra-binary shock heating of black widow companions |
the hawc collaboration has reported the detection of an extended γ -ray emission around the geminga and monogem pulsars of a few degree extension. very recently, the lhaaso collaboration released also the data for an extended γ -ray emission around the pulsar psr j0622+3749. this flux can be explained with electrons an... | do the geminga, monogem and psr j0622+3749 γ -ray halos imply slow diffusion around pulsars? |
fast radio bursts (frbs) are millisecond bursts of radio radiation whose progenitors, so far, remain mysterious. nevertheless, the timescales and energetics of these events have lead to many theories associating frbs with young neutron stars (nss). motivated by this, i explore the interaction of frbs with young superno... | the impact of a supernova remnant on fast radio bursts |
the interaction of a rotating star’s magnetic field with a surrounding plasma disk lies at the heart of many questions posed by neutron stars in x-ray binaries. we consider the opening of stellar magnetic flux due to differential rotation along field lines coupling the star and disk, using a simple model for the disk-o... | torque enhancement, spin equilibrium, and jet power from disk-induced opening of pulsar magnetic fields |
programmable arrays of hundreds of rydberg atoms have recently enabled the exploration of remarkable phenomena in many-body quantum physics. in addition, the development of high-fidelity quantum gates are making them promising architectures for the implementation of quantum circuits.we present herepulser, an open-sourc... | pulser: an open-source package for the design of pulse sequences in programmable neutral-atom arrays |
gravitational waves encode invaluable information about the nature of the relatively unexplored extreme gravity regime, where the gravitational interaction is strong, nonlinear and highly dynamical. recent gravitational wave observations by advanced ligo have provided the first glimpses into this regime, allowing for t... | theoretical physics implications of gravitational wave observation with future detectors |
assuming that the common-spectrum process in the nanograv 12.5-year dataset has an origin of scalar-induced gravitational waves, we study the enhancement of primordial curvature perturbations and the mass function of primordial black holes, by performing the bayesian parameter inference for the first time. we obtain lo... | bayesian implications for the primordial black holes from nanograv's pulsar-timing data using the scalar-induced gravitational waves |
roughly every 2-10 min, a pair of stellar-mass black holes merge somewhere in the universe. a small fraction of these mergers are detected as individually resolvable gravitational-wave events by advanced detectors such as ligo and virgo. the rest contribute to a stochastic background. we derive the statistically optima... | optimal search for an astrophysical gravitational-wave background |
using as references the posterior probability distribution functions of the equation of state (eos) parameters inferred from the radii of canonical neutron stars (nss) reported by the ligo/virgo and nicer collaborations based on their observations of gw170817 and psr j0030+0451, we investigate how future radius measure... | bayesian inference of the symmetry energy of superdense neutron-rich matter from future radius measurements of massive neutron stars |
magnetic reconnection is invoked as an efficient particle accelerator in a variety of astrophysical sources of non-thermal high-energy radiation. with large-scale two-dimensional particle-in-cell simulations of relativistic reconnection (i.e. with magnetization σ ≫ 1) in pair plasmas, we study the long-term evolution o... | the steady growth of the high-energy spectral cut-off in relativistic magnetic reconnection |
we synthesize the known information about fast radio bursts (frbs) and radio magnetars, and describe an allowed origin near nuclei of external, but non-cosmological, galaxies. this places them at z\ll 1, within a few hundred megaparsecs. in this scenario, the high dispersion measure (dm) is dominated by the environment... | local circumnuclear magnetar solution to extragalactic fast radio bursts |
supermassive black hole binaries, cosmic strings, relic gravitational waves from inflation, and first-order phase transitions in the early universe are expected to contribute to a stochastic background of gravitational waves in the 1 0-9- 1 0-7 h z frequency band. pulsar timing arrays (ptas) exploit the high-precision ... | time-domain implementation of the optimal cross-correlation statistic for stochastic gravitational-wave background searches in pulsar timing data |
the direct detection of gravitational waves with the next-generation detectors, like advanced ligo, provides the opportunity to measure deviations from the predictions of general relativity. one such departure would be the existence of alternative polarizations. to measure these, we study a single detector measurement ... | detecting beyond-einstein polarizations of continuous gravitational waves |
we present results from particle-in-cell simulations of driven turbulence in magnetized, collisionless, and relativistic pair plasmas. we find that the fluctuations are consistent with the classical k⊥-5 /3 magnetic energy spectrum at fluid scales and a steeper k⊥-4 spectrum at sub-larmor scales, where k⊥ is the wave v... | kinetic turbulence in relativistic plasma: from thermal bath to nonthermal continuum |
precise characterization of detector time resolution is of crucial importance for next-generation cryogenic-bolometer experiments searching for neutrinoless double-beta decay, such as cupid, in order to reject background due to pileup of two-neutrino double-beta decay events. in this paper, we describe a technique deve... | novel technique for the study of pileup events in cryogenic bolometers |
the chime/frb collaboration reports the detection of a radio burst from the direction of the known galactic magnetar sgr 1935+2154, which is currently in an active state (gcns #32675, #32698, #32706, #32708, #32737, and atels #15667, #15672, #15674). | chime/frb detection of a bright radio burst from sgr 1935+2154 |
the packed ultra-wideband mapping array (puma) is a proposed low-resolution transit interferometric radio telescope operating over the frequency range 200 - 1100mhz. its rich science portfolio will include measuring structure in the universe from redshift z = 0.3 to 6 using 21cm intensity mapping, detecting one million... | packed ultra-wideband mapping array (puma): astro2020 rfi response |
breakthrough listen is the most comprehensive and sensitive search for extraterrestrial intelligence (seti) to date, employing a collection of international observational facilities including both radio and optical telescopes. during the first three years of the listen program, thousands of targets have been observed w... | the breakthrough listen search for intelligent life: public data, formats, reduction, and archiving |
in agreement with the constantly increasing gravitational wave events, new aspects of the internal structure of compact stars can be considered. a scenario in which a first-order transition takes place inside these stars is of particular interest, as it can lead, under certain conditions, to a third gravitationally sta... | twin stars as probes of the nuclear equation of state: effects of rotation through the psr j0952-0607 pulsar and constraints via the tidal deformability from the gw170817 event |
the gravitational wave gw170817 is associated with the inspiral phase of a binary neutron star coalescence event. the ligo-virgo detectors' sensitivity at high frequencies was not sufficient to detect the signal corresponding to the merger and postmerger phases. hence, the question whether the merger outcome was a prom... | inferring prompt black-hole formation in neutron star mergers from gravitational-wave data |
the first x-ray pulsar, cen x-3, was discovered 50 yr ago. radiation from such objects is expected to be highly polarized due to birefringence of plasma and vacuum associated with propagation of photons in the presence of the strong magnetic field. here we present results of the observations of cen x-3 performed with t... | the x-ray polarimetry view of the accreting pulsar cen x-3 |
we present the measurements of faraday rotation for 477 pulsars observed by the parkes 64 m radio telescope and the green bank 100 m radio telescope. using these results, along with previous measurements for pulsars and extragalactic sources, we analyze the structure of the large-scale magnetic field in the galactic di... | pulsar rotation measures and large-scale magnetic field reversals in the galactic disk |
the x-ray afterglow plateau emission observed in many gamma-ray bursts (grbs) has been interpreted as being fueled either by fallback onto a newly formed black hole or by the spin-down luminosity of an ultra-magnetized millisecond neutron star. if the latter model is assumed, grb x-ray afterglow light curves can be rep... | on the magnetar origin of the grbs presenting x-ray afterglow plateaus |
the accretion-induced collapse (aic) scenario was proposed 40 years ago as an evolutionary end state of oxygen-neon white dwarfs (one wds), linking them to the formation of neutron star (ns) systems. however, there has been no direct detection of any aic event so far, even though there exists a lot of indirect observat... | the formation of neutron star systems through accretion-induced collapse in white-dwarf binaries |
the light curves of some luminous supernovae are suspected to be powered by the spindown energy of a rapidly rotating magnetar. here we describe a possible signature of the central engine: a burst of shock breakout emission occurring several days after the supernova explosion. the energy input from the magnetar inflate... | magnetar-driven shock breakout and double-peaked supernova light curves |
ultraluminous x-ray sources (ulxs) are a population of extragalactic objects whose luminosity exceeds the eddington limit for a 10 m ⊙ black hole (bh). their properties have been widely interpreted in terms of accreting stellar-mass or intermediate-mass bhs. however at least three neutron stars (nss) have been recently... | pulsator-like spectra from ultraluminous x-ray sources and the search for more ultraluminous pulsars |
we extend the quark mean-field (qmf) model for nuclear matter and study the possible presence of quark matter inside the cores of neutron stars. a sharp first-order hadron-quark phase transition is implemented combining the qmf for the hadronic phase with "constant-speed-of-sound" parameterization for the high-density ... | constraining hadron-quark phase transition parameters within the quark-mean-field model using multimessenger observations of neutron stars |
we have compiled a significantly updated and comprehensive census of massive stars in the nearby cygnus ob2 association by gathering and homogenizing data from across the literature. the census contains 169 primary ob stars, including 52 o-type stars and 3 wolf-rayet stars. spectral types and photometry are used to pla... | the massive star population of cygnus ob2 |
aims: in the present work we search for a new model of compact star within embedding class one spacetime i.e., four dimensional spacetime embedded in five dimensional pseudo euclidean space. methods: in particular we propose a new mass function to obtain an exact analytic solutions of the einstein field equations. for ... | compact stars with specific mass function |
neutron stars spin down over time due to a number of energy-loss processes. we provide tantalizing population-based evidence that millisecond pulsars (msps) have a minimum ellipticity of ɛ ≈ 10-9 around their spin axis and that, consequently, some spin down mostly through gravitational-wave emission. we discuss the imp... | evidence for a minimum ellipticity in millisecond pulsars |
the large magellanic cloud, a satellite galaxy of the milky way, has been observed with the high energy stereoscopic system (h.e.s.s.) above an energy of 100 billion electron volts for a deep exposure of 210 hours. three sources of different types were detected: the pulsar wind nebula of the most energetic pulsar known... | the exceptionally powerful tev γ-ray emitters in the large magellanic cloud |
the realm of strong classical gravity and perhaps even quantum gravity are waiting to be explored. in this letter we consider the recently detected triple system composed of two stars and a non-accreting black hole. using published observations of this system we conduct the most sensitive test to date for whether the b... | a sensitive search for wormholes |
corrections to general relativity that introduce long-ranged scalar fields which are nonminimally coupled to curvature typically predict that neutron stars possess a nontrivial scalar field profile anchored to the star. an observer far from a star is most sensitive to the spherically symmetric piece of this profile tha... | challenging the presence of scalar charge and dipolar radiation in binary pulsars |
we analyze families of hybrid equations of state of cold qcd matter, which combine input from gauge-gravity duality and from various ab initio methods for nuclear matter at low density, and predict that all neutron stars are fully hadronic without quark matter cores. we focus on constraints from recent measurements by ... | holographic qcd in the nicer era |
the measurement of the macroscopic properties of a neutron star, whether in binary or in an isolated system, provides us with a key opportunity to place a stringent constraint on its equation of state. in this paper, we perform bayesian model selection on a wide variety of neutron star equations of state using multi-me... | bayesian model selection of neutron star equations of state using multi-messenger observations |
the coherent oscillation of ultralight dark matter in the mass regime around 10-23 ev induces changes in gravitational potential with the frequency in the nanohertz range. this effect is known to produce a monochromatic signal in the pulsar timing residuals. here we discuss a multifield scenario that produces a wide sp... | pulsar timing residual induced by wideband ultralight dark matter with spin 0,1,2 |
most large galaxies host supermassive black holes in their nuclei and are subject to mergers, which can produce a supermassive black hole binary (smbhb), and hence periodic signatures due to orbital motion. we report unique periodic radio flux density variations in the blazar pks 2131-021, which strongly suggest an smb... | the unanticipated phenomenology of the blazar pks 2131-021: a unique supermassive black hole binary candidate |
we report the detection of steady radio emission from the known x-ray source x9 in the globular cluster 47 tuc. with a double-peaked c iv emission line in its ultraviolet spectrum providing a clear signature of accretion, this source had been previously classified as a cataclysmic variable. in deep atca (australia tele... | deep radio imaging of 47 tuc identifies the peculiar x-ray source x9 as a new black hole candidate |
numerical and observational evidence suggests that massive white dwarfs dominate the innermost regions of core-collapsed globular clusters by both number and total mass. using ngc 6397 as a test case, we constrain the features of white dwarf populations in core-collapsed clusters, both at present day and throughout the... | white dwarf subsystems in core-collapsed globular clusters |
radio pulsars scintillate because their emission travels through the ionized interstellar medium along multiple paths, which interfere with each other. it has long been realized that, independent of their nature, the regions responsible for the scintillation could be used as `interstellar lenses' to localize pulsar emi... | pulsar emission amplified and resolved by plasma lensing in an eclipsing binary |
alternative theories of gravity not only modify the polarization contents of the gravitational wave, but also affect the motions of the stars and the energy radiated away via the gravitational radiation. these aspects leave imprints in the observational data, which enables the test of general relativity and its alterna... | constraints on horndeski theory using the observations of nordtvedt effect, shapiro time delay and binary pulsars |
intensity scintillations of radio pulsars are known to originate from interference between waves scattered by the electron density irregularities of interstellar plasma, often leading to parabolic arcs in the two-dimensional power spectrum of the recorded dynamic spectrum. the degree of arc curvature depends on the dis... | precision orbital dynamics from interstellar scintillation arcs for psr j0437-4715 |
we study strange stars in the framework of f (r ,t ) theory of gravity. to provide exact solutions of the field equations it is considered that the gravitational lagrangian can be expressed as the linear function of the ricci scalar r and the trace of the stress-energy tensor t , i.e. f (r ,t )=r +2 χ t , where χ is a ... | anisotropic strange stars under simplest minimal matter-geometry coupling in the f (r ,t ) gravity |
the psrix backend is the primary pulsar timing instrument of the effelsberg 100 m radio telescope since early 2011. this new roach-based system enables bandwidths up to 500 mhz to be recorded, significantly more than what was possible with its predecessor, the effelsberg-berkeley pulsar processor (ebpp). we review the ... | prospects for high-precision pulsar timing with the new effelsberg psrix backend |
the detection of gravitational waves (gws) from a binary neutron star (bns) has opened a new window on gravitational wave astronomy. with current sensitivities, detectable signals coming from compact objects like neutron stars turn out to be a crucial ingredient for probing their structure, composition, and evolution. ... | quark stars in 4d einstein-gauss-bonnet gravity with an interacting quark equation of state |
we apply a number of statistical and machine learning techniques to classify and rank gamma-ray sources from the third fermi large area telescope source catalog (3fgl), according to their likelihood of falling into the two major classes of gamma-ray emitters: pulsars (psr) or active galactic nuclei (agns). using 1904 3... | classification and ranking of fermi lat gamma-ray sources from the 3fgl catalog using machine learning techniques |
we show that ultraluminous x-ray sources (ulxs) with coherent x-ray pulsing (pulxs) probably have neutron-star spin axes significantly misaligned from their central accretion discs. scattering in the funnels collimating their emission and producing their apparent super-eddington luminosities is the most likely origin o... | pulsing and non-pulsing ulxs: the iceberg emerges |
during the final stages of a compact object merger, if at least one of the binary components is a magnetized neutron star (ns), then its orbital motion substantially expands the ns's open magnetic flux - and hence increases its wind luminosity - relative to that of an isolated pulsar. as the binary orbit shrinks due to... | shock-powered radio precursors of neutron star mergers from accelerating relativistic binary winds |
the fermi large area telescope (lat) has opened the way for comparative studies of cosmic rays (crs) and high-energy objects in the milky way (mw) and in other, external, star-forming galaxies. using 2 yr of observations with the fermi lat, local group galaxy m31 was detected as a marginally extended gamma-ray source, ... | observations of m31 and m33 with the fermi large area telescope: a galactic center excess in andromeda? |
radio pulsars are believed to have their emission powered by the loss of rotational kinetic energy. by contrast, magnetars show intense x-ray and γ-ray radiation whose luminosity greatly exceeds that due to spin down and magnetar luminosity is believed to be powered by intense internal magnetic fields. a basic predicti... | a magnetar-like outburst from a high-b radio pulsar |
within the next several years, pulsar-timing array programs will likely usher in the next era of gravitational-wave astronomy through the detection of a stochastic background of nanohertz-frequency gravitational waves, originating from a cosmological population of inspiraling supermassive binary black holes. while the ... | from bright binaries to bumpy backgrounds: mapping realistic gravitational wave skies with pulsar-timing arrays |
the strength of neutron star crust is crucial for modelling magnetar flares, pulsar glitches, and gravitational wave emission. we aim to shed some light on this problem by analysing uniaxial stretch deformation (elongation and contraction) of perfect body-centered cubic coulomb crystals, paying special attention to the... | breaking properties of neutron star crust |
aims: the magnetic field of accreting neutron stars determines their overall behavior including the maximum possible luminosity. some models require an above-average magnetic field strength (≳1013 g) in order to explain super-eddington mass accretion rate in the recently discovered class of pulsating ultraluminous x-ra... | smc x-3: the closest ultraluminous x-ray source powered by a neutron star with non-dipole magnetic field |
we study the current sample of rapidly rotating neutron stars in both accreting and non-accreting binaries in order to determine whether the spin distribution of accreting neutron stars in low-mass x-ray binaries (lmxbs) can be reconciled with current accretion torque models. we perform a statistical analysis of the sp... | the spin distribution of fast-spinning neutron stars in low-mass x-ray binaries: evidence for two subpopulations |
we calculate the properties, occurrence rates and detection prospects of individually resolvable `single sources' in the low-frequency gravitational wave (gw) spectrum. our simulations use the population of galaxies and massive black hole binaries from the illustris cosmological hydrodynamic simulations, coupled to com... | single sources in the low-frequency gravitational wave sky: properties and time to detection by pulsar timing arrays |
a head-on collision between two dust ion acoustic solitary waves (diasws) travelling in the opposite direction in a weakly relativistic plasma composed of four distinct particle populations, namely, weakly relativistic ion fluid, superthermal electrons as well as positrons, and immobile dust, is investigated. by employ... | head-on collision of two dust ion acoustic solitary waves in a weakly relativistic multicomponent superthermal plasma |
cooling simulations of neutron stars and their comparison with the data from thermally emitting x-ray sources put constraints on the properties of axions, and by extension, of any light pseudoscalar dark matter particles, whose existence has been postulated to solve the strong-c p problem of qcd. we incorporate the axi... | axion cooling of neutron stars |
the double pulsar (psr j0737-3039) is the only neutron star-neutron star (ns-ns) binary in which both nss have been detectable as radio pulsars. the double pulsar has been assumed to dominate the galactic ns-ns binary merger rate r_g among all known systems, solely based on the properties of the first-born, recycled pu... | implications of psr j0737-3039b for the galactic ns-ns binary merger rate |
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