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we report on a full-polarization analysis of the first 25 as yet non-repeating frbs detected at 1.4 ghz by the 110-antenna deep synoptic array (dsa-110) during commissioning observations. we present details of the data-reduction, calibration, and analysis procedures developed for this novel instrument. the data have 32... | deep synoptic array science: polarimetry of 25 new fast radio bursts provides insights into their origins |
aims: taking advantage of more than 11 years of fermi-lat data, we perform a new and deep analysis of the pulsar wind nebula (pwn) hess j1825-137. combining this analysis with recent h.e.s.s. results we investigate and constrain the particle transport mechanisms at work inside the source as well as the system evolution... | energy dependent morphology of the pulsar wind nebula hess j1825-137 with fermi-lat |
axions are a promising dark matter candidate that were motivated to solve the strong charge-parity problem and that may also address the cosmological matter-antimatter asymmetry. axion-photon conversion is possible in the presence of the strong magnetic fields, and the photon so produced will have energy equal to the a... | new limits on axionic dark matter from the magnetar psr j1745-2900 |
high-energy radiation from nonthermal particles accelerated in relativistic magnetic reconnection is thought to be important in many astrophysical systems, ranging from blazar jets and black hole accretion disk coronae to pulsars and magnetar flares. the presence of a substantial density of high-energy photons (>mev... | effects of synchrotron cooling and pair production on collisionless relativistic reconnection |
pulsar timing array experiments search for phenomena that produce angular correlations in the arrival times of signals from millisecond pulsars. the primary goal is to detect an isotropic and stochastic gravitational wave background. we use simulated data to show that this search can be affected by the presence of othe... | a study of spatial correlations in pulsar timing array data |
a faraday rotation measure (rm) catalogue, or rm grid, is a valuable resource for the study of cosmic magnetism. using the second data release (dr2) from the lofar two-metre sky survey (lotss), we have produced a catalogue of 2461 extragalactic high-precision rm values across 5720 deg2 of sky (corresponding to a polari... | the faraday rotation measure grid of the lofar two-metre sky survey: data release 2 |
we report on six new chandra observations of the geminga pulsar wind nebula (pwn). the pwn consists of three distinct elongated structures—two ≈ 0.2{d}250 pc long lateral tails and a segmented axial tail of ≈ 0.05{d}250 pc length, where {d}250=d/(250 {pc}). the photon indices of the power-law spectra of the lateral tai... | geminga’s puzzling pulsar wind nebula |
the dense stellar environment of the galactic center has been proposed to host a large population of as-yet undetected millisecond pulsars (msps). recently, this hypothesis has found support in an analysis of gamma-rays detected using the large area telescope onboard the fermi satellite, which revealed an excess of dif... | radio detection prospects for a bulge population of millisecond pulsars as suggested by fermi-lat observations of the inner galaxy |
the determination of the polarization modes of gravitational waves (gws), and of their dispersion relations is decisive to scrutinize the viability of extended theories of gravity. a tool to investigate the polarization states of gws is the newman-penrose (np) formalism. however, if the speed of gws is smaller than the... | testing gravity with gauge-invariant polarization states of gravitational waves |
in this paper, we study compact binary millisecond pulsars with low- and very low-mass companion stars (spiders) in the galactic field, using data from the latest gaia data release (dr3). we infer the parallax distances of the optical counterparts to spiders, which we use to estimate optical and x-ray luminosities. we ... | a gaia view of the optical and x-ray luminosities of compact binary millisecond pulsars |
in this paper, we discuss the holographic first order qcd phase transition with gluon condensate and the generation of gravitational waves (gws) from the phase transition. the first order qcd phase transition is dual to the first order hawking-page phase transition from holography. we study the first order hawking-page... | gravitational waves from holographic qcd phase transition with gluon condensate |
close-orbit low-mass x-ray binaries (lmxbs), radio binary millisecond pulsars (bmsps) with extremely low-mass helium white dwarfs (elm he wds) and ultra-compact x-ray binaries (ucxbs) are all part of the same evolutionary sequence. it is therefore of uttermost importance to understand how these populations evolve from ... | formation of millisecond pulsars with helium white dwarfs, ultra-compact x-ray binaries, and gravitational wave sources |
we study the polarizations induced by the galileon as a stochastic gravitational wave background in the cross correlated power in a pulsar timing array. working within galileon gravity, we first show that the scalar gravitational wave signature of the galileon is encoded solely in its effective mass, which is controlle... | looking out for the galileon in the nanohertz gravitational wave sky |
spider pulsars are neutron stars that have a companion star in a close orbit. the companion star sheds material to the neutron star, spinning it up to millisecond rotation periods, while the orbit shortens to hours. the companion is eventually ablated and destroyed by the pulsar wind and radiation1,2. spider pulsars ar... | a binary pulsar in a 53-minute orbit |
reliable neutron star mass measurements are key to determining the equation of state of cold nuclear matter, but such measurements are rare. black widows and redbacks are compact binaries consisting of millisecond pulsars and semi-degenerate companion stars. spectroscopy of the optically bright companions can determine... | neutron star mass estimates from gamma-ray eclipses in spider millisecond pulsar binaries |
when galaxies merge, the supermassive black holes in their centers may form binaries and emit low-frequency gravitational radiation in the process. in this paper, we consider the galaxy 3c 66b, which was used as the target of the first multimessenger search for gravitational waves. due to the observed periodicities pre... | multimessenger gravitational-wave searches with pulsar timing arrays: application to 3c 66b using the nanograv 11-year data set |
in magnetized capacitively coupled radio frequency (rf) plasmas operated at low pressure, the magnetic asymmetry effect (mae) provides the opportunity to control the discharge symmetry, the dc self-bias, and the ion energy distribution functions at boundary surfaces by adjusting a magnetic field, that is oriented paral... | magnetic control of nonlinear electron resonance heating in a capacitively coupled radio frequency discharge |
binary pulsars are affected by general relativity (gr), causing the spin axis of each pulsar to precess. we present polarimetric radio observations of the pulsar psr j1906+0746 that demonstrate the validity of the geometrical model of pulsar polarization. we reconstruct the (sky-projected) polarization emission map ove... | radio emission from a pulsar’s magnetic pole revealed by general relativity |
in the framework of einstein's the theory of general relativity we present a new interior solution with a perfect fluid, this is constructed from the proposal of a gravitational redshift factor. the geometry is regular and its density and pressure are monotonic decrescent functions, furthermore the sound speed is small... | a perfect fluid model for compact stars |
more than 50 years after the discovery of pulsars1 and confirmation of their association with supernova explosions2-4, the origin of the initial spin and velocity of pulsars remains largely a mystery. the typical space velocities of several hundred km s−1 have been attributed to `kicks' resulting from asymmetries eithe... | evidence for three-dimensional spin-velocity alignment in a pulsar |
we have constructed mocassin photoionization plus dust radiative transfer models for the crab nebula core-collapse supernova (ccsn) remnant, using either smooth or clumped mass distributions, in order to determine the chemical composition and masses of the nebular gas and dust. we computed models for several different ... | the dust and gas content of the crab nebula |
gravitational waves (gws) cause the apparent position of distant stars to oscillate with a characteristic pattern on the sky. astrometric measurements (e.g., those made by gaia) provide a new way to search for gws. the main difficulty facing such a search is the large size of the data set; gaia observes more than one b... | astrometric search method for individually resolvable gravitational wave sources with gaia |
understanding the natal kicks, or birth velocities, of neutron stars is essential for understanding the evolution of massive binaries and double neutron star formation. we use maximum likelihood methods as published in verbunt et al. to analyse a new large data set of parallaxes and proper motions measured by deller et... | the observed velocity distribution of young pulsars - ii. analysis of complete psrπ |
aims: we aim to present a first step in developing a benchmark equation-of-state (eos) model for multi-messenger astronomy that unifies the thermodynamics of quark and hadronic degrees of freedom.methods: a lagrangian approach to the thermodynamic potential of quark-meson-nucleon matter was used. in this approach, dyna... | toward a unified equation of state for multi-messenger astronomy |
scintillation of compact radio sources results from the interference between images caused by multipath propagation, and probes the intervening scattering plasma and the velocities of the emitting source and scattering screen. in frb20201124a, a repeating fast radio burst (frb) that entered a period of extreme activity... | scintillation time-scale measurement of the highly active frb20201124a |
the historic first detection of the binary neutron star merger gw170817 by the ligo-virgo collaboration has set a limit on the gravitational deformability of neutron stars. in contrast, radio observations of psr j 0740 +6620 find a very massive neutron star. tension between the small deformability and the large maximum... | large sound speed in dense matter and the deformability of neutron stars |
galactic double neutron star systems have a tight mass distribution around ∼1.35m⊙, but the mass distribution of all known pulsars is broader (tauris et al. 2017). here we reconstruct the alsing et al. (2018), antoniadis et al. (2016) bimodal mass distribution of pulsars observed in binary systems, incorporating data f... | a population-informed mass estimate for pulsar j0740+6620 |
fast radio bursts (frbs) are millisecond-duration signals that are highly dispersed at distant galaxies. however, the physical origin of frbs is still unknown. coherent curvature emission by bunches, e.g., powered by starquakes, has already been proposed for repeating frbs. it has the nature of understanding narrowband... | repeating fast radio bursts: coherent circular polarization by bunches |
wetlands are impacted by economic and political initiatives, and research on their ecosystem health is attracting increasing public attention. it is crucial that management decisions for wetland ecosystems quantify the whole ecosystem health status. in this paper, we aimed to precisely assess the ecosystem health for j... | ecosystem health assessment: a psr analysis combining ahp and fce methods for jiaozhou bay, china1 |
we examine the capability of pulsar timing arrays (ptas) to detect very small-scale clumps of dark matter (dm), which are a natural outcome of the standard cold dark matter (cdm) paradigm. a clump streaming near the earth or a pulsar induces an impulsive acceleration to encode residuals on pulsar timing data. we show t... | detectability of small-scale dark matter clumps with pulsar timing arrays |
upcoming fast radio burst (frb) surveys will search ∼103 beams on the sky with a very high duty cycle, generating large numbers of single-pulse candidates. the abundance of false positives presents an intractable problem if candidates are to be inspected by eye, making it a good application for artificial intelligence ... | applying deep learning to fast radio burst classification |
we study electron-positron pair production in polar caps of energetic pulsars to determine the maximum multiplicity of pair plasma a pulsar can produce under the most favorable conditions. this paper complements and updates our study of pair cascades presented in timokhin & harding (2015) with a more accurate treat... | on the maximum pair multiplicity of pulsar cascades |
the mergers of supermassive black hole binaries (smbhbs) promise to be incredible sources of gravitational waves (gws). while the oscillatory part of the merger gravitational waveform will be outside the frequency sensitivity range of pulsar timing arrays, the nonoscillatory gw memory effect is detectable. further, any... | the nanograv 11 yr data set: limits on gravitational wave memory |
the widths, dispersion measures (dms), dispersion indices, and fluences of fast radio bursts (frbs) impose coupled constraints that all models must satisfy. the non-monotonic dependence of burst widths (after deconvolution of instrumental effects) on dms excludes the intergalactic medium as the location of scattering t... | inferences from the distributions of fast radio burst pulse widths, dispersion measures, and fluences |
spontaneous scalarization is a gravitational phenomenon in which deviations from general relativity arise once a certain threshold in curvature is exceeded, while being entirely absent below that threshold. for black holes, scalarization is known to be triggered by a coupling between a scalar and the gauss-bonnet invar... | black hole scalarization with gauss-bonnet and ricci scalar couplings |
written by a leading expert, this monograph presents recent developments on supernova remnants, with the inclusion of results from various satellites and ground-based instruments. the book details the physics and evolution of supernova remnants, as well as provides an up-to-date account of recent multiwavelength result... | physics and evolution of supernova remnants |
we present photometry and spectroscopy of ps1-14bj, a hydrogen-poor superluminous supernova (slsn) at redshift z = 0.5215 discovered in the last months of the pan-starrs1 medium deep survey. ps1-14bj stands out because of its extremely slow evolution, with an observed rise of ≳ 125 rest-frame days, and exponential decl... | ps1-14bj: a hydrogen-poor superluminous supernova with a long rise and slow decay |
we demonstrate that future radius measurements of the nicer mission have the potential to reveal the existence of a strong phase transition in dense neutron star matter by confirming the existence of so-called twin stars, compact star configurations with the same mass but different radii. the latest radius constraints ... | confirming the existence of twin stars in a nicer way |
a long-lived scalar field (φ) which couples weakly to the right-handed (rh) neutrinos (nri), generates small rh neutrino masses (mi) in low-scale-leptogenesis (lsl) mechanisms, despite having a large vacuum expectation value vφ. in this case, the correlation shared by the mis and the duration of the non-standard cosmic... | gravitational waves-tomography of low-scale-leptogenesis |
using data from the hawc gamma-ray telescope, we have studied a sample of 37 millisecond pulsars (msps), selected for their spindown power and proximity. from among these msp, we have identified four which favor the presence of very high-energy gamma-ray emission at a level of (2 δ ln l )1/2≥2.5 . adopting a correlatio... | evidence of tev halos around millisecond pulsars |
the 6.67 hr periodicity and the variable x-ray flux of the central compact object (cco) at the center of the supernova remnant rcw 103, named 1e 161348-5055, have been always difficult to interpret within the standard scenarios of an isolated neutron star (ns) or a binary system. on 2016 june 22, the burst alert telesc... | magnetar-like activity from the central compact object in the snr rcw103 |
context. the sardinia radio telescope (srt) is the new 64 m dish operated by the italian national institute for astrophysics (inaf). its active surface, comprised of 1008 separate aluminium panels supported by electromechanical actuators, will allow us to observe at frequencies of up to 116 ghz. at the moment, three re... | the sardinia radio telescope . from a technological project to a radio observatory |
enterprise (enhanced numerical toolbox enabling a robust pulsar inference suite) is a pulsar-timing analysis code which performs noise analysis, gravitational-wave searches, and timing model analysis. it uses tempo2 (ascl:1210.015) to find the maximum-likelihood fit for the timing parameters and the basis of the fit fo... | enterprise: enhanced numerical toolbox enabling a robust pulsar inference suite |
the discovery of the first binary pulsar in 1974 has opened up a completely new field of experimental gravity. in numerous important ways, pulsars have taken precision gravity tests quantitatively and qualitatively beyond the weak-field slow-motion regime of the solar system. apart from the first verification of the ex... | gravity tests with radio pulsars |
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 dim... | constraining free parameters of a color superconducting nonlocal nambu-jona-lasinio model using bayesian analysis of neutron stars mass and radius measurements |
context. the formation of a large-scale current sheet is a generic feature of pulsar magnetospheres. if the magnetic axis is misaligned with the star rotation axis, the current sheet is an oscillatory structure filling an equatorial wedge determined by the inclination angle, known as the striped wind. relativistic reco... | dissipation of the striped pulsar wind and non-thermal particle acceleration: 3d pic simulations |
we investigate the effects of the modified f(r, t) gravity on the charged strange quark stars with the standard choice of f(r, t)=r+2χ t. those types of stars are supposed to be made of strange quark matter (sqm) whose distribution is governed by the phenomenological mit bag eos as p=1/3(ρ-4b), where b is the bag const... | study on charged strange stars in f(r, t) gravity |
this study simulates strange stars in f(q) gravity with an additional source under an electric field using gravitational decoupling by means of the complete geometric deformation (cgd) technique. by employing the tolman ansatz and the mit bag model equation of state (eos), we explore bounded star configurations derived... | influence of three parameters on maximum mass and stability of strange star under linear f(q) - action |
we suggest that fast-rising blue optical transients (fbots) and the brightest event of the class, at2018cow, result from an electron-capture collapse to a neutron star following the merger of a massive onemg white dwarf (wd) with another wd. two distinct evolutionary channels lead to the disruption of the less-massive ... | fast-rising blue optical transients and at2018cow following electron-capture collapse of merged white dwarfs |
the deep synoptic array 10-dish prototype (dsa-10) is an instrument designed to detect and localize fast radio bursts with arcsecond accuracy in real time. deployed at owens valley radio observatory, it consists of ten 4.5-m diameter dishes, equipped with a 250-mhz bandwidth dual polarization receiver, centred at 1.4 g... | dsa-10: a prototype array for localizing fast radio bursts |
the ams-02 collaboration has just released its first result of the cosmic positron fraction e+ / (e- +e+) with high precision up to ∼350 gev. the ams-02 result shows the same trend with the previous pamela result, which requires extra electron/positron sources on top of the conventional cosmic ray background, either fr... | implications of the ams-02 positron fraction in cosmic rays |
integrating femtosecond (fs) lasers to electron microscopies has enabled direct imaging of transient structures and morphologies of materials in real time and space, namely, ultrafast electron microscopy (uem). here we report the development of a laser-free uem offering the same capability of real-time imaging with hig... | direct visualization of electromagnetic wave dynamics by laser-free ultrafast electron microscopy |
prospects of establishing the radii of massive neutron stars in psr j1614 - 2230 and psr j0740 + 6620 from neutron star interior composition explorer and chandra observatories hold the potential to constrain the equation of state (eos) of matter to densities well beyond those encountered in canonical stars of mass $\si... | on the minimum radius of very massive neutron stars |
the north american nanohertz observatory for gravitational waves (nanograv) has recently reported strong statistical evidence for a common-spectrum red-noise process for all pulsars, as seen in their 12.5-yr analysis for an isotropic stochastic gravitational-wave signal. however, there is currently very little evidence... | common-spectrum process versus cross-correlation for gravitational-wave searches using pulsar timing arrays |
qcd axions or axionlike particles are among the most popular candidates for cold dark matter (dm) in the universe. we proposed to detect axionlike dm, using linearly polarized pulsar light as a probe. because of birefringence effect potentially caused by an oscillating galactic axion dm background, when pulsar light tr... | detecting axionlike dark matter with linearly polarized pulsar light |
recently, the radius of neutron star (ns) psr j 0740 +6620 was measured by neutron star interior composition explorer (nicer), and an updated measurement of neutron skin thickness of 208pb (rskin208 ) was reported by the prex-ii experiment. these new measurements can help us better understand the unknown equation of st... | constraints on the phase transition and nuclear symmetry parameters from psr j 0740 +6620 and multimessenger data of other neutron stars |
inspired by the conundrum of the gravitational event gw190814, which brings to light the coalescence of a 23 m ⊙ black hole with a yet-to-be-determined secondary component, we look to modeling compact objects within the framework of $f({ \mathcal q })$ gravity by employing the method of gravitational decoupling. we imp... | the effect of gravitational decoupling on constraining the mass and radius for the secondary component of gw190814 and other self-bound strange stars in f(q) gravity theory |
axion dark matter can be converted into photons in the magnetospheres of neutron stars leading to a spectral line centered on the compton wavelength of the axion. due to the rotation of the star and the plasma effects in the magnetosphere the signal is predicted to be periodic with significant time variation that persi... | searching for time-dependent axion dark matter signals in pulsars |
in this work, we interpreted the high braking index of psr j1640-4631 with a combination of the magneto-dipole radiation and dipole magnetic field decay models. by introducing a mean rotation energy conversion coefficient \overline{\zeta }, the ratio of the total high-energy photon energy to the total rotation energy l... | the dipole magnetic field and spin-down evolutions of the high braking index pulsar psr j1640-4631 |
the mpifr-meerkat galactic plane survey at l-band (mmgps-l) is the most sensitive pulsar survey in the southern hemisphere, providing 78 discoveries in an area of 900 sq. deg. here, we present a follow-up study of one of these new discoveries, psr j1208−5936, a 28.71-ms recycled pulsar in a double neutron star system w... | the mpifr-meerkat galactic plane survey. ii. the eccentric double neutron star system psr j1208−5936 and a neutron star merger rate update |
the origin of fast radio bursts (frbs) remains mysterious. recently, the only repeating frb source, frb 121102, was reported to possess an extremely large and variable rotation measure (rm). the inferred magnetic field strength in the burst environment is comparable to that in the vicinity of the supermassive black hol... | frb 121102: a repeatedly combed neutron star by a nearby low-luminosity accreting supermassive black hole |
direct detection of gravitational waves is opening a new window onto our universe. here, we study the sensitivity to continuous-wave strain fields of a kg-scale optomechanical system formed by the acoustic motion of superfluid helium-4 parametrically coupled to a superconducting microwave cavity. this narrowband detect... | detecting continuous gravitational waves with superfluid 4he |
background: an accurate determination of the core-crust transition is necessary in the modeling of neutron stars for astrophysical purposes. the transition is intimately related to the isospin dependence of the nuclear force at low baryon densities. purpose: to study the symmetry energy and the core-crust transition in... | higher-order symmetry energy and neutron star core-crust transition with gogny forces |
the neutron star interior composition explorer (nicer) is looking for neutron stars and pulsars from its perch on the international space station. keith gendreau and zaven arzoumanian provide an overview of its capabilities. | searching for a pulse |
radio interferometers have the ability to precisely localize and better characterize the properties of sources. this ability is having a powerful impact on the study of fast radio transients, where a few milliseconds of data is enough to pinpoint a source at cosmological distances. however, recording interferometric da... | realfast: real-time, commensal fast transient surveys with the very large array |
we present a model for a super-eddington accretion disc around a magnetized neutron star taking into account advection of heat and the mass loss by the wind. the model is semi-analytical and predicts radial profiles of all the basic physical characteristics of the accretion disc. the magnetospheric radius is found as a... | super-eddington accretion discs with advection and outflows around magnetized neutron stars |
one very promising technique for measuring the dense matter equation of state exploits hotspots that form on the neutron star surface due to the pulsar mechanism, accretion streams, or during thermonuclear explosions in the neutron star ocean. this article explains how pulse profile modeling of hotspots is being used b... | constraining the neutron star equation of state using pulse profile modeling |
according to the general-relativistic no-hair theorem, astrophysical black holes depend only on their masses and spins and are uniquely described by the kerr metric. mass and spin are the first two multipole moments of the kerr spacetime and completely determine all other moments. the no-hair theorem can be tested by m... | testing the no-hair theorem with observations of black holes in the electromagnetic spectrum |
lorentz symmetry is one of the pillars of both general relativity and the standard model of particle physics. motivated by ideas about quantum gravity, unification theories and violations of cpt symmetry, a significant effort has been put the last decades into testing lorentz symmetry. this review focuses on lorentz sy... | tests of lorentz symmetry in the gravitational sector |
in 2019 november, maxi detected an x-ray outburst from the known be x-ray binary system rx j0209.6-7427 located in the outer wing of the small magellanic cloud. we followed the outburst of the system with nicer, which led to the discovery of x-ray pulsations with a period of 9.3 s. we analysed simultaneous x-ray data o... | the 2019 super-eddington outburst of rx j0209.6-7427: detection of pulsations and constraints on the magnetic field strength |
despite significant efforts over the past decade, the origin of the cosmic ray positron excess has still not been unambiguously established. a popular class of candidate sources are pulsars or pulsar wind nebulae but these cannot also account for the observed hard spectrum of cosmic ray antiprotons. we revisit the alte... | explaining cosmic ray antimatter with secondaries from old supernova remnants |
magnetic reconnection in the relativistic regime has been proposed as an important process for the efficient production of nonthermal particles and high-energy emission. using fully kinetic particle-in-cell simulations, we investigate how the guide-field strength and domain size affect the characteristic spectral featu... | particle injection and nonthermal particle acceleration in relativistic magnetic reconnection |
it has recently been discovered that a fraction of ultraluminous x-ray sources (ulxs) exhibit x-ray pulsations, and are therefore powered by super-eddington accretion on to magnetized neutron stars (nss). for typical ulx mass accretion rates ({≳ } 10^{19} {g s^{-1}}), the inner parts of the accretion disc are expected ... | timing properties of ulx pulsars: optically thick envelopes and outflows |
to date, the most precise tests of general relativity have been achieved through pulsar timing, albeit in the weak-field regime. since pulsars are some of the most precise and stable "clocks" in the universe, present observational efforts are focused on detecting pulsars in the vicinity of supermassive black holes (mos... | test-particle dynamics in general spherically symmetric black hole spacetimes |
in the present work, we try to find a solution without singularity of einstein's field equations for the spherically symmetric perfect fluid objects, accurately strange quark spheres, taking into consideration schwarzschild metric as the outside space-time. an ensemble of inside solutions found on the basis of the simp... | a spherically symmetric model of anisotropic fluid for strange quark spheres |
we present the first detection of x-ray coherent pulsations from the transitional millisecond pulsar xss j12270-4859, while it was in a sub-luminous accretion disc state characterized by a 0.5-10 kev luminosity of 5 × 1033 erg s-1 (assuming a distance of 1.4 kpc). pulsations were observed by xmm-newton at an rms amplit... | x-ray coherent pulsations during a sub-luminous accretion disc state of the transitional millisecond pulsar xss j12270-4859. |
we initiate a study on various cosmological imprints of string axions whose scalar potentials have plateau regions. in such cases, we show that a delayed onset of oscillation rather generically leads to a parametric resonance instability. in particular, for ultralight axions, the parametric resonance can enhance the po... | cosmological imprints of string axions in plateau |
we identify new astrophysical signatures of dark matter that implodes neutron stars (nss), which could decisively test whether ns-imploding dark matter is responsible for missing pulsars in the milky way galactic center, the source of some r -process elements, and the origin of fast-radio bursts. first, ns-imploding da... | searching for dark matter with neutron star mergers and quiet kilonovae |
this work presents an algorithm for modeling a static spherically symmetric compact object satisfying the eiesland condition (eiesland in am math soc 27:213, 1925), a necessary and sufficient condition that a general centro-symmetric space shall be of the class 1. the model parameters are obtained accordingly by employ... | some families of relativistic anisotropic compact stellar models embedded in pseudo-euclidean space e^5: an algorithm |
superconductors are excellent testbeds for studying vortices, topological excitations that also appear in superfluids, liquid crystals and bose-einstein condensates. vortex motion can be disruptive; it can cause phase transitions, glitches in pulsars, and losses in superconducting microwave circuits, and it limits the ... | universal lower limit on vortex creep in superconductors |
binary neutron star mergers can be sources of gravitational waves coincident with electromagnetic counterpart emission across the spectrum. to solidify their role as multimessenger sources, we present fully 3d, general relativistic, magnetohydrodynamic simulations of highly spinning binary neutrons stars initially on q... | magnetohydrodynamic simulations of binary neutron star mergers in general relativity: effects of magnetic field orientation on jet launching |
pulsar dispersion measures (dms) have been used to model the electron density of the interstellar medium (ism) in the galactic disk as a plane-parallel medium, despite significant scatter in the dm-distance distribution and strong evidence for inhomogeneities in the ism. we use a sample of pulsars with independent dist... | electron density structure of the local galactic disk |
we build a model of radius-to-frequency mapping in magnetospheres of neutron stars and apply it to frequency drifts observed in fast radio bursts (frbs). we assume that an emission patch propagates along the dipolar magnetic field lines, producing coherent emission with frequency, direction, and polarization defined by... | radius-to-frequency mapping and frb frequency drifts |
the anomalous x-ray pulsar xte j1810-197 was the first magnetar found to emit pulsed radio emission. after spending almost a decade in a quiescent, radio-silent state, the magnetar was reported to have undergone a radio outburst in 2018 december. we observed radio pulsations from xte j1810-197 during this early phase o... | wideband polarized radio emission from the newly revived magnetar xte j1810-197 |
ngc 300 ulx1 is an ultraluminous x-ray pulsar, showing an unprecedented spin evolution, from about 126 s to less than 20 s in only 4 yr, consistent with steady mass accretion rate. following its discovery we have been monitoring the system with swift and nicer to further study its properties. we found that even though ... | ngc 300 ulx1: spin evolution, super-eddington accretion, and outflows |
the repeating fast radio burst (frb) 121102 was recently localized in a dwarf galaxy at a cosmological distance. the dispersion measure (dm) derived for each burst from frb 121102 so far has not shown significant evolution, even though an apparent increase was recently seen with newly detected vla bursts. it is expecte... | dispersion measure variation of repeating fast radio burst sources |
we describe the x-ray pulse profile models we use and how we use them to analyze neutron star interior composition explorer (nicer) observations of rotation-powered millisecond pulsars to obtain information about the mass-radius relation of neutron stars and the equation of state of the dense matter in their cores. her... | constraining the neutron star mass-radius relation and dense matter equation of state with nicer. iii. model description and verification of parameter estimation codes |
hyperons are essential constituents in the neutron star interior. the poorly known hyperonic interaction is a source of uncertainty for studying laboratory hypernuclei and neutron star observations. in this work, we perform bayesian inference of phenomenological hyperon-nucleon interactions using the tidal deformabilit... | astrophysical implications on hyperon couplings and hyperon star properties with relativistic equations of states |
supermassive black hole binary systems (smbhbs) emitting gravitational waves may be traced by periodic light curves. we assembled a catalog of 149 such periodic light curves, and using their masses, distances, and periods, predicted the gravitational-wave strain and detectability of each binary candidate using all-sky ... | multimessenger pulsar timing array constraints on supermassive black hole binaries traced by periodic light curves |
with the first multi messenger observation of a binary neutron star merger (gw170817), new constraints became available for masses and radii of neutron stars. we introduce a class of hybrid eos that fulfills all these constraints and predicts a region in the mass radius diagram that could be populated only by hybrid ne... | studying the onset of deconfinement with multi messenger astronomy of neutron stars |
a successful measurement of the stochastic gravitational wave background (sgwb) in pulsar timing arrays (ptas) would open up a new window through which to test the predictions of general relativity (gr). we consider how these measurements might reveal deviations from gr by studying the overlap reduction function - the ... | a test of gravity with pulsar timing arrays |
we show that gravitational wave emission from neutron star binaries can be used to discover any generic long-ranged muonic force due to the large inevitable abundance of muons inside neutron stars. as a minimal consistent example, we focus on a gauged u(1 ) lμ-lτ symmetry. in pulsar binaries, such u(1 ) lμ-lτ vectors i... | probing muonic forces with neutron star binaries |
the galactic center excess (gce) of gev gamma rays can be explained as a signal of annihilating dark matter or of emission from unresolved astrophysical sources, such as millisecond pulsars. evidence for the latter is provided by a statistical procedure—referred to as non-poissonian template fitting (nptf)—that disting... | characterizing the nature of the unresolved point sources in the galactic center: an assessment of systematic uncertainties |
we explore the effects of strangeness and δ resonance in baryonic matter and compact stars within the relativistic-mean-field models. the parameter set pkdd is adopted for n -n interaction, parameters fixed based on finite hypernuclei and neutron stars are taken for the hyperon-meson couplings, and the universal baryon... | strangeness and δ resonance in compact stars with relativistic-mean-field models |
fast radio bursts (frbs) are millisecond radio signals that exhibit dispersion larger than what the galactic electron density can account for. we have conducted a 1446 h survey for frbs at 145 mhz, covering a total of 4193 deg2 on the sky. we used the uk station of the low frequency array (lofar) radio telescope - the ... | limits on fast radio bursts at 145 mhz with artemis, a real-time software backend |
it is currently not known if repeating fast radio bursts (frbs) are fundamentally different from those that have not been seen to repeat. one striking difference between repeaters and apparent non-repeaters in the canadian hydrogen intensity mapping experiment sample is that the once-off events are typically shorter in... | beaming as an explanation of the repetition/width relation in frbs |
we report on a search for dark matter axion conversion photons from the magnetosphere of the galactic center magnetar psr j1745-2900 using spectra obtained from the karl g. jansky very large array (the national radio astronomy observatory is a facility of the national science foundation operated under cooperative agree... | search for axionic dark matter using the magnetar psr j1745-2900 |
radio pulsar observations probe the lives of galactic double neutron star (dns) systems while gravitational waves enable us to study extragalactic dns in their final moments. by combining measurements from radio and gravitational-wave astronomy, we seek to gain a more complete understanding of dns from formation to mer... | heavy double neutron stars: birth, midlife, and death |
binary pulsars provide some of the tightest current constraints on modified theories of gravity and these constraints will only get tighter as radio astronomers continue timing these systems. these binary pulsars are particularly good at constraining scalar-tensor theories in which gravity is mediated by a scalar field... | binary pulsar constraints on massless scalar-tensor theories using bayesian statistics |
we report on a detailed spectral analysis of the transient x-ray pulsar 1a 0535+262, which underwent the brightest giant outburst ever recorded for this source from 2020 november to december with a peak luminosity of 1.2 × 1038 erg s-1. thanks to the unprecedented energy coverage and high-cadence observations provided ... | luminosity dependence of the cyclotron line energy in 1a 0535+262 observed by insight-hxmt during the 2020 giant outburst |
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