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by using observations of the hulse-taylor pulsar, we constrain the gravitational wave (gw) speed to the level of 1 0-2 . we apply this result to scalar-tensor theories that generalize galileon 4 and 5 models, which display anomalous propagation speed and coupling to matter for gws. we argue that this effect survives co... | evading the vainshtein mechanism with anomalous gravitational wave speed: constraints on modified gravity from binary pulsars |
context. the environment of sagittarius a* (sgr a*), the central black hole of the milky way, is the only place in the universe where we can currently study the interaction between a nuclear star cluster and a massive black hole and infer the properties of a nuclear cluster from observations of individual stars.aims: t... | the milky way's nuclear star cluster: old, metal-rich, and cuspy. structure and star formation history from deep imaging |
this paper presents the new photometer ce318-t, able to perform daytime and night-time photometric measurements using the sun and the moon as light source. therefore, this new device permits a complete cycle of diurnal aerosol and water vapour measurements valuable to enhance atmospheric monitoring to be extracted. in ... | the new sun-sky-lunar cimel ce318-t multiband photometer - a comprehensive performance evaluation |
there is growing evidence that the galactic center excess identified in the fermi-lat gamma-ray data arises from a population of faint astrophysical sources. we provide compelling supporting evidence by showing that the morphology of the excess traces the stellar over-density of the galactic bulge. by adopting a templa... | strong evidence that the galactic bulge is shining in gamma rays |
magnetic reconnection is a leading mechanism for dissipating magnetic energy and accelerating nonthermal particles in poynting-flux-dominated flows. in this letter, we investigate nonthermal particle acceleration during magnetic reconnection in a magnetically dominated ion-electron plasma using fully kinetic simulation... | efficient production of high-energy nonthermal particles during magnetic reconnection in a magnetically dominated ion-electron plasma |
accreting millisecond x-ray pulsars (amxps) are an important subset of low-mass x-ray binaries (lmxbs) in which coherent x-ray pulsations can be observed during occasional, bright outbursts (x-ray luminosity {l}{{x}}∼ {10}36 {erg} {{{s}}}-1). these pulsations show that matter is being channeled onto the neutron star’s ... | accretion-powered pulsations in an apparently quiescent neutron star binary |
this study explores the implications of dark matter in neutron stars (dmans) by focusing on two specific astronomical objects: hess j1731-347 and psr j0952-0607. varying the fermi momentum k$f^{\rm dm}$ of dm, the study analyzes the eos for the inrs model with and without dm. results show the robustness of the model, w... | dark matter admixed neutron star in the light of hess j1731-347 and psr j0952-0607 |
the possible detection of a compact object in the remnant of sn 1987a presents an unprecedented opportunity to follow its early evolution. the suspected detection stems from an excess of infrared emission from a dust blob near the compact object's predicted position. the infrared excess could be due to the decay of iso... | ns 1987a in sn 1987a |
we present a search for continuous gravitational-wave emission due to r-modes in the pulsar psr j0537-6910 using data from the ligo-virgo collaboration observing run o3. psr j0537-6910 is a young energetic x-ray pulsar and is the most frequent glitcher known. the inter-glitch braking index of the pulsar suggests that g... | constraints from ligo o3 data on gravitational-wave emission due to r-modes in the glitching pulsar psr j0537-6910 |
gravitational wave detectors are formidable tools to explore strong-field gravity, especially black holes and neutron stars. these compact objects are extraordinarily efficient at producing electromagnetic and gravitational radiation. as such, they are ideal laboratories for fundamental physics and have an immense disc... | snowmass2021 cosmic frontier white paper: fundamental physics and beyond the standard model |
several pulsar timing array (pta) collaborations recently announced the first detection of a stochastic gravitational wave (gw) background, leaving open the question of its source. we explore the possibility that it originates from cosmic inflation, a guaranteed source of primordial gw. the inflationary gw background a... | dark energy, d-branes and pulsar timing arrays |
in the axion monodromy inflation, the inflation is driven by the axion with super-planckian field values in a monomial potential with superimposed sinusoidal modulations. the coupling of the axion to massless gauge fields can induce copious particle production during inflation, resulting in large non-gaussian curvature... | primordial black holes and associated gravitational waves in axion monodromy inflation |
the discovery of two neutron star-black hole coalescences by ligo and virgo brings the total number of likely neutron stars observed in gravitational waves to six. we perform the first inference of the mass distribution of this extragalactic population of neutron stars. in contrast to the bimodal galactic population de... | the mass distribution of neutron stars in gravitational-wave binaries |
we describe the survey for pulsars and extragalactic radio bursts (superb), an ongoing pulsar and fast transient survey using the parkes radio telescope. superb involves real-time acceleration searches for pulsars and single-pulse searches for pulsars and fast radio bursts. we report on the observational set-up, data a... | the survey for pulsars and extragalactic radio bursts - i. survey description and overview |
if cosmic strings are formed in the early universe, their associated loops emit gravitational waves during the whole cosmic history and contribute to the stochastic gravitational wave background at all frequencies. we provide a new estimate of the stochastic gravitational wave spectrum by considering a realistic cosmol... | stochastic gravitational waves from cosmic string loops in scaling |
we describe the aperture tile in focus (apertif) system, a phased array feed (paf) upgrade of the westerbork synthesis radio telescope that transforms this telescope into a high-sensitivity, wide-field-of-view l-band imaging and transient survey instrument. using novel paf technology, up to 40 partially overlapping bea... | apertif: phased array feeds for the westerbork synthesis radio telescope. system overview and performance characteristics |
we study a family of equations of state (eos) for hybrid neutron star matter. the hybrid eos are obtained by a maxwell construction of the first-order phase transition between a hadronic phase described by the relativistic density-functional eos of the "dd2" class with excluded volume effects and a deconfined quark mat... | quark-nuclear hybrid equation of state for neutron stars under modern observational constraints |
the variables and slow transients survey (vast) on the australian square kilometre array pathfinder (askap) is designed to detect highly variable and transient radio sources on timescales from 5 s to $∼ 5$ yr. in this paper, we present the survey description, observation strategy and initial results from the vast phase... | the askap variables and slow transients (vast) pilot survey |
we report the discovery of psr j1757-1854, a 21.5-ms pulsar in a highly-eccentric, 4.4-h orbit with a neutron star (ns) companion. psr j1757-1854 exhibits some of the most extreme relativistic parameters of any known pulsar, including the strongest relativistic effects due to gravitational-wave damping, with a merger t... | the high time resolution universe pulsar survey - xiii. psr j1757-1854, the most accelerated binary pulsar |
dark matter substructure on small scales is currently weakly constrained, and its study may shed light on the nature of the dark matter. in this work we study the gravitational effects of dark matter substructure on measured pulsar phases in pulsar timing arrays (ptas). due to the stability of pulse phases observed ove... | observability of dark matter substructure with pulsar timing correlations |
gravitational wave memory is theorized to arise from the integrated history of gravitational wave emission, and manifests as a spacetime deformation in the wake of a propagating gravitational wave. we explore the detectability of the memory signals from a population of coalescencing supermassive black hole binaries wit... | prospects for memory detection with low-frequency gravitational wave detectors |
we study the dynamics of (i) neutral test particles, (ii) magnetically charged test particles, and (iii) test magnetic dipole around a regular bardeen black hole surrounded by perfect fluid dark matter (pfdm). it has been shown how the magnetic charge of the black hole and the parameter of the surrounding pfdm can infl... | dynamics of test particles around a bardeen black hole surrounded by perfect fluid dark matter |
we explore the correlation of γ-ray emitting blazars with icecube neutrinos by using three very recently completed, and independently built, catalogues and the latest neutrino lists. we introduce a new observable, namely the number of neutrino events with at least one γ-ray counterpart, nν. in all three catalogues we c... | extreme blazars as counterparts of icecube astrophysical neutrinos |
partial observability -- where agents can only observe partial information about the true underlying state of the system -- is ubiquitous in real-world applications of reinforcement learning (rl). theoretically, learning a near-optimal policy under partial observability is known to be hard in the worst case due to an e... | partially observable rl with b-stability: unified structural condition and sharp sample-efficient algorithms |
we report on imaging x-ray polarimetry explorer (ixpe) observations of the be-transient x-ray pulsar ls v +44 17/rx j0440.9+4431 made at two luminosity levels during the giant outburst in january-february 2023. considering the observed spectral variability and changes in the pulse profiles, the source was likely caught... | complex variations in x-ray polarization in the x-ray pulsar ls v +44 17/rx j0440.9+4431 |
the optically good quality single crystals of triphenylphosphine oxide 4-nitrophenol (tp4n) with maximum dimension of 15 × 10 × 5 mm3 were grown by slow evaporation solution technique (sest) at room temperature. the cell dimensions of the grown tp4n crystal were confirmed by single crystal x-ray diffraction (sxrd) and ... | crystal growth, structural, optical, thermal, mechanical, laser damage threshold and electrical properties of triphenylphosphine oxide 4-nitrophenol (tp4n) single crystals for nonlinear optical applications |
using simulations of non-rotating supernova progenitors, we explore the kicks imparted to and the spins induced in the compact objects birthed in core collapse. we find that the recoil due to neutrino emissions can be a factor affecting core recoil, comparable to and at times larger than the corresponding kick due to m... | kicks and induced spins of neutron stars at birth |
in this work, we are guided by the gravitational wave events gw 170817 and gw 190814 together with observations of neutron stars psr j1614-2230, psr j1903+6620, and lmc x-4 to model compact objects within the framework of einstein-gauss-bonnet (egb) gravity. in addition, we employ the extended gravitational decoupling ... | observational constraints on maximum mass limit and physical properties of anisotropic strange star models by gravitational decoupling in einstein-gauss-bonnet gravity |
we present a statistical study of the glitch population and the behaviour of the glitch activity across the known population of neutron stars. an unbiased glitch database was put together based on systematic searches of radio timing data of 898 rotation-powered pulsars obtained with the jodrell bank and parkes observat... | the glitch activity of neutron stars |
we point out that the observed time delay between the detection of the signal at the hanford and livingston ligo sites from the gravitational wave event gw150914 places an upper bound on the speed of propagation of gravitational waves, c gw ≲ 1.7 in the units of speed of light. combined with the lower bound from the ab... | on constraining the speed of gravitational waves following gw150914 |
we study the screening mechanism in the most general scalar-tensor theories that leave gravitational waves unaffected and are thus compatible with recent ligo/virgo observations. using the effective field theory of the dark energy approach, we consider the general action for perturbations beyond linear order, focusing ... | vainshtein regime in scalar-tensor gravity: constraints on degenerate higher-order scalar-tensor theories |
pulsar timing and laser-interferometer gravitational-wave (gw) detectors are superb laboratories to study gravity theories in the strong-field regime. here, we combine these tools to test the mono-scalar-tensor theory of damour and esposito-farèse (def), which predicts nonperturbative scalarization phenomena for neutro... | constraining nonperturbative strong-field effects in scalar-tensor gravity by combining pulsar timing and laser-interferometer gravitational-wave detectors |
the observation of gravitational waves from a binary neutron star merger by ligo/virgo and the associated electromagnetic counterpart provides a high precision test of orbital dynamics, and therefore a new and sensitive probe of extra forces and new radiative degrees of freedom (d.o.f.). axions are one particularly wel... | prospects for axion searches with advanced ligo through binary mergers |
we present the discovery of 24 pulsars in 15 globular clusters (gcs) using the five-hundred-meter aperture spherical radio telescope (fast). these include the first pulsar discoveries in m2, m10, and m14. most of the new systems are either confirmed or likely members of binary systems. m53c and ngc 6517h and i are the ... | fast globular cluster pulsar survey: twenty-four pulsars discovered in 15 globular clusters |
if dark matter has a sizable scattering cross section with nucleons, it can efficiently be captured by a neutron star. its energy is then transferred to the neutron star as heat through the scattering and annihilation inside the star. this heating effect may be detectable via dedicated temperature observations of nearb... | capture of electroweak multiplet dark matter in neutron stars |
we present an overview of the lofar tied-array all-sky survey (lotaas) for radio pulsars and fast transients. the survey uses the high-band antennas of the lofar superterp, the dense inner part of the lofar core, to survey the northern sky (δ > 0°) at a central observing frequency of 135 mhz. a total of 219 tied-arr... | the lofar tied-array all-sky survey (lotaas): survey overview and initial pulsar discoveries |
this paper is the second in a series where we report the results of the long-term timing of the millisecond pulsars (msps) in 47 tucanae with the parkes 64-m radio telescope. we obtain improved timing parameters that provide additional information for studies of the cluster dynamics: (a) the pulsar proper motions yield... | long-term observations of the pulsars in 47 tucanae - ii. proper motions, accelerations and jerks |
the fermi large area telescope has observed an excess of ∼gev energy gamma rays from the center of the milky way, which may arise from near-thermal dark matter annihilation. firmly establishing the dark matter origin for this excess is however complicated by challenges in modeling diffuse cosmic-ray foregrounds as well... | foreground mismodeling and the point source explanation of the fermi galactic center excess |
the two-body problem under the influence of both dark energy and post-newtonian modifications is studied. in this unified framework, we demonstrate that dark energy plays the role of a critical period with $t_{\lambda} = 2\pi/c \sqrt{\lambda} \approx 60~\text{gyr}$. we also show that the ratio between orbital and criti... | dark energy as a critical period in binary motion: bounds from multi-scale binaries |
big bang nucleosynthesis (bbn) is very sensitive to the cosmological expansion rate. if the gravitational constant g took a different value during the nucleosynthesis epoch than today, the primordial abundances of light elements would be affected. in this work, we improve the bounds on this variation using recent deter... | improved bbn constraints on the variation of the gravitational constant |
xss j12270-4859 is an x-ray binary associated with the fermi large area telescope gamma-ray source 1fgl j1227.9-4852. in 2012 december, this source underwent a transition where the x-ray and optical luminosity dropped and the spectral signatures of an accretion disk disappeared. we report the discovery of a 1.69 millis... | discovery of psr j1227-4853: a transition from a low-mass x-ray binary to a redback millisecond pulsar |
double neutron stars (dns) have to survive two supernovae (sne) and still remain bound. this sets strong limits on the nature of the second collapse in these systems. we consider the masses and orbital parameters of the dns population and constrain the two distributions of mass ejection and kick velocities directly fro... | formation of double neutron star systems as implied by observations |
we consider the three currently known pulsing ultraluminous x-ray sources (pulxs). we show that in one of them the observed spin-up rate requires super-eddington accretion rates at the magnetospheric radius, even if magnetar-strength fields are assumed. in the two other systems, a normal-strength neutron star field imp... | pulsing ulxs: tip of the iceberg? |
the microscopic quantum nature of elementary particles, chirality, leads to macroscopic phenomena like the chiral anomaly, chiral magnetic effect, and chiral plasma instability. we review recent progress of the studies of these chiral effects in high-energy astrophysics, such as pulsar kicks, magnetars, and core-collap... | chiral effects in astrophysics and cosmology |
the canadian hydrogen intensity mapping experiment (chime) has become a leading facility for detecting fast radio bursts (frbs) through the chime/frb backend. chime/frb searches for fast transients in polarization-summed intensity data streams that have 24 khz spectral and 1 ms temporal resolution. the intensity beams ... | an analysis pipeline for chime/frb full-array baseband data |
this work analyses the hydrostatic equilibrium configurations of strange stars in a non-minimal geometry-matter coupling (gmc) theory of gravity. those stars are made of strange quark matter, whose distribution is governed by the mit equation of state. the non-minimal gmc theory is described by the following gravitatio... | quark stars with 2.6 m⊙ in a non-minimal geometry-matter coupling theory of gravity |
gamma-ray observations have established energetic isolated pulsars as outstanding particle accelerators and antimatter factories. however, many questions are still open regarding the acceleration and radiation processes involved, as well as the locations where they occur. the radiation spectra of all gamma-ray pulsars ... | discovery of a radiation component from the vela pulsar reaching 20 teraelectronvolts |
this paper presents the first systematic study of proto-neutron star (pns) convection in three dimensions (3d) based on our latest numerical fornax models of core-collapse supernova (ccsn). we confirm that pns convection commonly occurs, and then quantify the basic physical characteristics of the convection. by virtue ... | a systematic study of proto-neutron star convection in three-dimensional core-collapse supernova simulations |
in this letter we propose that coherent radio emission of the crab pulsar, other young energetic pulsars, and millisecond pulsars is produced in the magnetospheric current sheet beyond the light cylinder. we carry out global and local 2d kinetic plasma simulations of reconnection to illustrate the coherent emission mec... | pulsar radio emission mechanism: radio nanoshots as a low-frequency afterglow of relativistic magnetic reconnection |
the newly discovered second repeating fast radio burst (frb) source, frb 180814.j0422+73, was reported to exhibit a time-frequency downward drifting pattern, which is also seen in the first repeater frb 121102. we propose a generic geometrical model to account for the observed downward drifting of sub-pulse frequency, ... | on the time-frequency downward drifting of repeating fast radio bursts |
millisecond pulsars have been discussed as a possible source of the gamma-ray excess observed from the region surrounding the galactic center. with this in mind, we use the observed population of bright low-mass x-ray binaries to estimate the number of millisecond pulsars in the inner galaxy. this calculation suggests ... | challenges in explaining the galactic center gamma-ray excess with millisecond pulsars |
we search for the isotropic stochastic gravitational-wave background, including the nontensorial polarizations that are allowed in general metric theories of gravity, in the parkes pulsar timing array (ppta) second data release (dr2). we find no statistically significant evidence that the common-spectrum process report... | constraining the polarization of gravitational waves with the parkes pulsar timing array second data release |
the 2015 centenary of the publication of einstein's general theory of relativity, and the first detection of gravitational waves have focused renewed attention on the question of whether einstein was right. this review of experimental gravity provides a detailed survey of the intensive testing of einstein's theory of g... | theory and experiment in gravitational physics |
we present first results from a lofar census of non-recycled pulsars. the census includes almost all such pulsars known (194 sources) at declinations dec > 8° and galactic latitudes |gb| > 3°, regardless of their expected flux densities and scattering times. each pulsar was observed for ≥20 min in the contiguous ... | a lofar census of non-recycled pulsars: average profiles, dispersion measures, flux densities, and spectra |
we derive constraints on millicharged dark matter and axionlike particles using pulsar timing and fast radio burst observations. for dark matter particles of charge ɛ e , the constraint from time of arrival (toa) of waves is ɛ /mmilli≲10-8 ev-1 , for masses mmilli≳10-6 ev . for axionlike particles, the polarization of ... | constraints on millicharged dark matter and axionlike particles from timing of radio waves |
the aim of this work is to study the imprints that different models for black hole (bh) and neutron star (ns) formation have on the galactic distribution of x-ray binaries (xrbs) that contain these objects. we find that the root mean square of the height above the galactic plane of bh- and ns-xrbs is a powerful proxy t... | the galactic distribution of x-ray binaries and its implications for compact object formation and natal kicks |
the 2016 vela glitch observed by the mount pleasant radio telescope provides the first opportunity to study pulse-to-pulse dynamics of a pulsar glitch, opening up new possibilities to study the neutron star's interior. we fit models of the star's rotation frequency to the pulsar data, and present the following three re... | rotational evolution of the vela pulsar during the 2016 glitch |
we determined faraday rotation measures (rms) towards 137 pulsars in the northern sky, using low-frequency array (lofar) observations at 110-190 mhz. this low-frequency rm catalogue, the largest to date, improves the precision of existing rm measurements on average by a factor of 20 - due to the low frequency and wide ... | low-frequency faraday rotation measures towards pulsars using lofar: probing the 3d galactic halo magnetic field |
the standard model of particle physics is known to be intriguingly successful. however, their rich phenomena represented by the phase transitions (pts) have not been completely understood yet, including the possibility of the existence of unknown dark sectors. in this paper, we investigate the measurement of the equati... | induced gravitational waves as a cosmological probe of the sound speed during the qcd phase transition |
the explosion of core-collapse supernova depends on a sequence of events taking place in less than a second in a region of a few hundred kilometers at the centre of a supergiant star, after the stellar core approaches the chandrasekhar mass and collapses into a proto-neutron star, and before a shock wave is launched ac... | the explosion mechanism of core-collapse supernovae: progress in supernova theory and experiments |
aims: the last comprehensive catalogue of high-mass x-ray binaries in the small magellanic cloud (smc) was published about ten years ago. since then new such systems were discovered, mainly by x-ray observations with chandra and xmm-newton. for the majority of the proposed hmxbs in the smc no x-ray pulsations were disc... | high-mass x-ray binaries in the small magellanic cloud |
over 100 millisecond radio pulsars (msps) have been observed in globular clusters (gcs), motivating theoretical studies of the formation and evolution of these sources through stellar evolution coupled to stellar dynamics. here we study msps in gcs using realistic n-body simulations with our cluster monte carlo code. w... | millisecond pulsars and black holes in globular clusters |
the millisecond pulsar j1713+0747 underwent a sudden and significant pulse shape change between april 16 and 17, 2021 (mjds 59320 and 59321). subsequently, the pulse shape gradually recovered over the course of several months. we report the results of continued multi-frequency radio observations of the pulsar made usin... | an unusual pulse shape change event in psr j1713+0747 observed with the green bank telescope and chime |
we review more than 10 yr of continuous monitoring of accreting x-ray pulsars with the all-sky gamma-ray burst monitor (gbm) aboard the fermi gamma-ray space telescope. our work includes data from the start of gbm operations in 2008 august, through to 2019 november. pulsations from 39 accreting pulsars are observed ove... | the ups and downs of accreting x-ray pulsars: decade-long observations with the fermi gamma-ray burst monitor |
ultralight dark matter (uldm) is proposed as a theoretical candidate of dark matter particles with masses of approximately 10-22 ev . the interactions between uldm particles and standard model particles would cause variations in pulse arrival times of millisecond pulsars, which means that the pulsar timing array (pta) ... | constraining ultralight dark matter using the fermi-lat pulsar timing array |
we investigate the effect of electric charge in anisotropic compact stars with conformal symmetry. we assume that the pressure and the density of the matter inside the stellar structure are large with strong gravitational fields. the strong electric field produces significant effects on the phenomenology of the stellar... | effect of electric charge on conformal compact stars |
in this work we discuss the polarization contents of einstein-æther theory and the generalized tensor-vector-scalar (teves) theory, as both theories have a normalized timelike vector field. we derive the linearized equations of motion around the flat spacetime background using the gauge-invariant variables to easily se... | gravitational waves in einstein-æther and generalized teves theory after gw170817 |
the quantity and quality of cosmic structure observations have greatly accelerated in recent years, and further leaps forward will be facilitated by imminent projects. these will enable us to map the evolution of dark and baryonic matter density fluctuations over cosmic history. the way that these fluctuations vary ove... | growth of cosmic structure: probing dark energy beyond expansion |
motivated by the large body of literature around the phenomenological properties of accreting black hole (bh) and neutron star (ns) x-ray binaries in the radio:x-ray luminosity plane, we carry out a comparative regression analysis on 36 bhs and 41 nss in hard x-ray states, with data over 7 dex in x-ray luminosity for b... | hard state neutron star and black hole x-ray binaries in the radio:x-ray luminosity plane |
recently a repeating fast radio burst (frb) 121102 has been confirmed to be an extragalactic event and a persistent radio counterpart has been identified. while other possibilities are not ruled out, the emission properties are broadly consistent with murase et al. that theoretically proposed quasi-steady radio emissio... | testing the young neutron star scenario with persistent radio emission associated with frb 121102 |
isolated spinning neutron stars, asymmetric with respect to their rotation axis, are expected to be sources of continuous gravitational waves. the most sensitive searches for these sources are based on accurate matched filtering techniques that assume the continuous wave to be phase locked with the pulsar beamed emissi... | narrow-band search for gravitational waves from known pulsars using the second ligo observing run |
recently, an indicative evidence of a stochastic process, reported by the nanograv collaboration based on the analysis of 12.5-year pulsar timing array data which might be interpreted as a potential stochastic gravitational wave signal, has aroused the keen interest of theorists. the first-order color charge confinemen... | nanograv signal from first-order confinement-deconfinement phase transition in different qcd-matter scenarios |
a sample of 14 frbs with measured redshifts and scattering times is used to assess contributions to dispersion and scattering from the intergalactic medium (igm), galaxy halos, and the disks of host galaxies. the igm and galaxy halos contribute significantly to dispersion measures (dms) but evidently not to scattering,... | redshift estimation and constraints on intergalactic and interstellar media from dispersion and scattering of fast radio bursts |
the nanograv, parkes, european, and international pulsar timing array (pta) collaborations have reported evidence for a common-spectrum process that can potentially correspond to a stochastic gravitational wave background (sgwb) in the 1-100 nhz frequency range. we consider the scenario in which this signal is produced... | gravitational wave signal from primordial magnetic fields in the pulsar timing array frequency band |
observations have shown that spatially extended "tev halos" are a common (and potentially generic) feature surrounding young and middle-aged pulsars. however, their morphology is not understood. they are larger than the "compact" region where the stellar remnant dominates the properties of the interstellar medium, but ... | self-generated cosmic-ray turbulence can explain the morphology of tev halos |
we present the timing and spectral studies of rx j0209.6-7427 during its rare 2019 outburst using observations with the soft x-ray telescope (sxt) and large area x-ray proportional counter (laxpc) instruments on the astrosat satellite. pulsations having a periodicity of 9.29 s were detected for the first time by the ni... | study of recent outburst in the be/x-ray binary rx j0209.6-7427 with astrosat: a new ultraluminous x-ray pulsar in the magellanic bridge? |
context. the gravitational strong equivalence principle (sep) is a cornerstone of the general theory of relativity (gr). hence, testing the validity of sep is of great importance when confronting gr, or its alternatives, with experimental data. pulsars that are orbited by white dwarf companions provide an excellent lab... | an improved test of the strong equivalence principle with the pulsar in a triple star system |
the phase state of dense matter in the intermediate density range ($\sim$ 1-10 times the nuclear saturation density) is both intriguing and unclear and can have important observable effects in the present gravitational wave era of neutron stars. as matter density increases in compact stars, the sound velocity is expect... | sound velocity in dense stellar matter with strangeness and compact stars |
the f (r) gravity can be cast into the form of a scalar-tensor theory, and scalar degree of freedom can be suppressed in high-density regions by the chameleon mechanism. in this article, for the general f (r) gravity, using a scalar-tensor representation with the chameleon mechanism, we calculate the parametrized post-... | constraining f(r) gravity in solar system, cosmology and binary pulsar systems |
plasmoids—magnetized quasi-circular structures formed self-consistently in reconnecting current sheets—were previously considered to be the graveyards of energetic particles. in this paper, we demonstrate the important role of plasmoids in shaping the particle energy spectrum in relativistic reconnection (i.e., with up... | secondary energization in compressing plasmoids during magnetic reconnection |
fast radio bursts (frbs) are millisecond bursts of radio radiation at frequencies of about 1 ghz, recently discovered in pulsar surveys. they have not yet been definitively identified with any other astronomical object or phenomenon. the bursts are strongly dispersed, indicating passage through a high column density of... | fast radio bursts — a brief review: some questions, fewer answers |
fast radio bursts (frbs) display a confounding variety of burst properties and host-galaxy associations. repeating frbs offer insight into the frb population by enabling spectral, temporal, and polarimetric properties to be tracked over time. here, we report on the polarized observations of 12 repeating sources using m... | revealing the dynamic magnetoionic environments of repeating fast radio burst sources through multiyear polarimetric monitoring with chime/frb |
the hot big bang is often considered as the origin of all matter and radiation in the universe. primordial nucleosynthesis provides strong evidence that the early universe contained a hot plasma of photons and baryons with a temperature t >mev . however, the earliest probes of dark matter originate from much later t... | dark matter and gravitational waves from a dark big bang |
we report the discovery of 1.97 ms period gamma-ray pulsations from the 75 minute orbital-period binary pulsar now named psr j1653-0158. the associated fermi large area telescope gamma-ray source 4fgl j1653.6-0158 has long been expected to harbor a binary millisecond pulsar. despite the pulsar-like gamma-ray spectrum a... | discovery of a gamma-ray black widow pulsar by gpu-accelerated einstein@home |
while pulsars possess exceptional rotational stability, large-scale timing studies have revealed at least two distinct types of irregularities in their rotation: red timing noise and glitches. using modern bayesian techniques, we investigated the timing noise properties of 300 bright southern-sky radio pulsars that hav... | the utmost pulsar timing programme - ii. timing noise across the pulsar population |
an equation of state of cold nuclear matter with an arbitrary isotopic composition is studied within a relativistic mean-field approach with hadron masses and coupling constants depending self-consistently on the scalar mean-field. all hadron masses decrease universally with the scalar field growth, whereas meson-nucle... | relativistic mean-field models with scaled hadron masses and couplings: hyperons and maximum neutron star mass |
the nearby radio pulsar b0950$+$08 with full duty cycle is targeted by the five-hundred-meter aperture spherical radio telescope (fast, 110 minutes allocated), via adopting polarization calibration on two ways of baseline determination, in order to understand its magnetospheric radiation geometry as well as the polar c... | radio pulsar b0950$+$08: radiation in magnetosphere and sparks above surface |
axion dark matter can resonantly convert to photons in the magnetosphere of neutron stars, possibly giving rise to radio signals observable on earth. this method for the indirect detection of axion dark matter has recently received significant attention in the literature. the calculation of the radio signal is complica... | axion-photon conversion in strongly magnetised plasmas |
we present a novel calculation of the spectrum of electrons and positrons from random sources, supernova remnants and pulsars, distributed within the spiral arms of the galaxy. the pulsar emissivity in terms of electron-positron pairs is considered as time dependent, following the magnetic dipole spin-down luminosity, ... | galactic factories of cosmic-ray electrons and positrons |
we provide timing solutions for 45 radio pulsars discovered by the robert c. byrd green bank telescope. these pulsars were found in the green bank north celestial cap pulsar survey, an all-gbt-sky survey being carried out at a frequency of 350 {mhz}. we include pulsar timing data from the green bank telescope and low f... | the green bank north celestial cap pulsar survey. iii. 45 new pulsar timing solutions |
we present high signal-to-noise ratio, multifrequency polarization pulse profiles for 24 millisecond pulsars that are being observed as part of the parkes pulsar timing array project. the pulsars are observed in three bands, centred close to 730, 1400 and 3100 mhz, using a dual-band 10 cm/50 cm receiver and the central... | a study of multifrequency polarization pulse profiles of millisecond pulsars |
we report the first star formation history study of the milky ways nuclear star cluster (nsc), which includes observational constraints from a large sample of stellar metallicity measurements. these metallicity measurements were obtained from recent surveys from gemini and the very large telescope of 770 late-type star... | the star formation history of the milky way's nuclear star cluster |
radio observations using five-hundred-metre aperture spherical radio telescope (fast) detected a highly polarised radio burst from sgr 1935+2154 at mjd 58969.9048669008. | a highly polarised radio burst detected from sgr 1935+2154 by fast |
with unparalleled rotational stability, millisecond pulsars (msps) serve as ideal laboratories for numerous astrophysical studies, many of which require precise knowledge of the distance and/or velocity of the msp. here, we present the astrometric results for 18 msps of the 'mspsr$\pi$' project focusing exclusively on ... | the mspsrπ catalogue: vlba astrometry of 18 millisecond pulsars |
neutron stars (nss) obtain kicks, typically of several 100 km s-1, at birth. the gravitational tugboat mechanism can explain these kicks as consequences of asymmetric mass ejection during the supernova (sn) explosion. support for this hydrodynamic explanation is provided by observations of sn remnants with associated n... | hydrodynamical neutron-star kicks in electron-capture supernovae and implications for the crab supernova |
the regularity of pulsar emissions becomes apparent once we reference the pulses' times of arrivals to the inertial rest frame of the solar system. it follows that errors in the determination of earth's position with respect to the solar system barycenter can appear as a time-correlated bias in pulsar-timing residual t... | modeling the uncertainties of solar system ephemerides for robust gravitational-wave searches with pulsar-timing arrays |
binary neutron stars (bnss) mergers are prime sites for r-process nucleosynthesis. their rate determines the chemical evolution of heavy elements in the milky way. the merger rate of bns is a convolution of their birth rate and the gravitational radiation spiral-in delay time. using the observed population of galactic ... | the gravitational waves merger time distribution of binary neutron star systems |
the radio spectral index is a powerful probe for classifying cosmic radio sources and understanding the origin of the radio emission. combining data at 147 mhz and 1.4 ghz from the tifr gmrt sky survey (tgss) and the nrao vla sky survey (nvss), we produced a large-area radio spectral index map of ∼80 per cent of the sk... | a radio spectral index map and catalogue at 147-1400 mhz covering 80 per cent of the sky |
we present a search for quasi-monochromatic gravitational-wave signals from the young, energetic x-ray pulsar psr j0537-6910 using data from the second and third observing runs of ligo and virgo. the search is enabled by a contemporaneous timing ephemeris obtained using neutron star interior composition explorer (nicer... | diving below the spin-down limit: constraints on gravitational waves from the energetic young pulsar psr j0537-6910 |
neutron stars are among the most exotic objects in the universe. a neutron star, with a mass of 1.4-2 solar masses within a radius of about 10-15 km, is the most compact stable configuration of matter in which degeneracy pressure can still balance gravity, since further compression would lead to gravitational collapse ... | accretion powered x-ray millisecond pulsars |
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