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we examine the cosmological and astrophysical signatures of a "dark baryon," a neutral fermion that mixes with the neutron. as the mixing is through a higher-dimensional operator at the quark level, production of the dark baryon at high energies is enhanced so that its abundance in the early universe may be significant... | cosmological and astrophysical probes of dark baryons |
the spacetime surrounding compact objects such as neutron stars and black holes provides an excellent place to study gravity in the strong, nonlinear, dynamical regime. here, the effects of strong curvature can leave their imprint on observables which we may use to study gravity. recently, nicer provided a mass and rad... | tidal deformabilities of neutron stars in scalar-gauss-bonnet gravity and their applications to multimessenger tests of gravity |
background: we analyze several constraints on the nuclear equation of state (eos) currently available from neutron star (ns) observations and laboratory experiments and study the existence of possible correlations among properties of nuclear matter at saturation density with ns observables. methods: we use a set of dif... | a modern view of the equation of state in nuclear and neutron star matter |
a first-order mev-scale cosmological phase transition (pt) can generate a peak in the power spectrum of stochastic gravitational wave background around nanohertz frequencies. with the recent international pulsar timing array data release two covering nanohertz frequencies, we search for such a phase transition signal. ... | squeezing cosmological phase transitions with international pulsar timing array |
we study the asymptotically flat spacetime in chern-simons modified gravity and then gravitational memory effects are considered in this work. if the chern-simons scalar does not directly couple with the ordinary matter fields, there are also displacement, spin, and center-of-mass memory effects as in general relativit... | asymptotic analysis of chern-simons modified gravity and its memory effects |
this manuscript investigates the compact stars solutions in the background of observational data (radii and mass) by employing the karmarkar condition under the f(g , t) modified gravity for an anisotropic source of fluid. for this study, we have assumed a specific model for grr metric potential function, which has ful... | realistic solutions of fluid spheres in f(g , t) gravity under karmarkar condition |
for decades, observations of faraday rotation have provided unique insights into the plasma density and magnetic field structure of the solar wind. faraday rotation (fr) is the rotation of the plane of polarization when linearly polarized radiation propagates through a magnetized plasma, such as the solar corona, coron... | modern faraday rotation studies to probe the solar wind |
we reconsider the problem of the hyperon puzzle and its suggested solution by quark deconfinement within the two-phase approach to hybrid compact stars with recently obtained hadronic and quark matter equations of state. for the hadronic phase we employ the hypernuclear equation of state from the lowest order constrain... | first-order phase transition from hypernuclear matter to deconfined quark matter obeying new constraints from compact star observations |
pulsar wind nebulae, blazars, gamma ray bursts and magnetars all contain regions where the electromagnetic energy density greatly exceeds the plasma energy density. these sources exhibit dramatic flaring activity where the electromagnetic energy distributed over large volumes, appears to be converted efficiently into h... | magnetoluminescence |
in this work we explore the evolution of magnetic fields inside strongly magnetized neutron stars in axisymmetry. we model numerically the coupled field evolution in the core and the crust. our code models the hall drift and ohmic effects in the crust, the back-reaction on the field from magnetically induced elastic de... | magnetic field evolution of neutron stars - i. basic formalism, numerical techniques and first results |
we apply collisionless particle-in-cell simulations of relativistic pair plasmas to explore whether driven turbulence is a viable high-energy astrophysical particle accelerator. we characterize nonthermal particle distributions for varying system sizes up to l/2πρe0 = 163, where l/2π is the driving scale and ρe0 is the... | system-size convergence of nonthermal particle acceleration in relativistic plasma turbulence |
popular models of repeating fast radio bursts (frbs; and perhaps of all frbs) involve neutron stars because of their high rotational or magnetostatic energy densities. these models take one of two forms: giant but rare pulsar-like pulses like those of rotating radio transients, and outbursts like those of soft gamma re... | are fast radio bursts made by neutron stars? |
we present global fits of an effective field theory description of real, and complex scalar dark matter candidates. we simultaneously take into account all possible dimension 6 operators consisting of dark matter bilinears and gauge invariant combinations of quark and gluon fields. we derive constraints on the free mod... | effective field theory of dark matter: a global analysis |
we present techniques developed to calibrate and correct murchison widefield array low-frequency (72-300 mhz) radio observations for polarimetry. the extremely wide field-of-view, excellent instantaneous (u, v)-coverage and sensitivity to degree-scale structure that the murchison widefield array provides enable instrum... | the challenges of low-frequency radio polarimetry: lessons from the murchison widefield array |
we describe directed searches for continuous gravitational waves (gws) in data from the sixth laser interferometer gravitational-wave observatory (ligo) science data run. the targets were nine young supernova remnants not associated with pulsars; eight of the remnants are associated with non-pulsing suspected neutron s... | searches for continuous gravitational waves from nine young supernova remnants |
context. lofar offers the unique capability of observing pulsars across the 10-240 mhz frequency range with a fractional bandwidth of roughly 50%. this spectral range is well suited for studying the frequency evolution of pulse profile morphology caused by both intrinsic and extrinsic effects such as changing emission ... | wide-band, low-frequency pulse profiles of 100 radio pulsars with lofar |
context. many energetic supernovae (sne) are thought to be powered by the rotational energy of a highly magnetized, rapidly rotating neutron star. the emission from the associated luminous pulsar wind nebula (pwn) can photoionize the sn ejecta, leading to a nebular spectrum of the ejecta with signatures that might reve... | toward nebular spectral modeling of magnetar-powered supernovae |
pulsars have been identified as good candidates for the acceleration of cosmic rays, up to ultra-high energies. however, a precise description of the acceleration processes at play is still to be established. using 2d particle-in-cell simulations, we study proton acceleration in axisymmetric pulsar magnetospheres. prot... | proton acceleration in pulsar magnetospheres |
the north american nanohertz observatory for gravitational waves (nanograv) collaboration has recently reported strong evidence for a stochastic process affecting the 12.5 yr dataset of pulsar timing residuals. we show that the signal can be interpreted in terms of a stochastic gravitational wave background emitted fro... | qcd axion and gravitational waves in light of nanograv results |
we explore the potential of pulsar timing arrays (ptas) such as nanograv, epta, and ppta to detect the stochastic gravitational wave background in theories of massive gravity. in general relativity, the function describing the dependence of the correlation between the arrival times of signals from two pulsars on the an... | detecting the stochastic gravitational wave background from massive gravity with pulsar timing arrays |
after large galaxies merge, their central supermassive black holes are expected to form binary systems. their orbital motion should generate a gravitational wave background (gwb) at nanohertz frequencies. searches for this background use pulsar timing arrays, which perform long-term monitoring of millisecond pulsars at... | a gamma-ray pulsar timing array constrains the nanohertz gravitational wave background |
observations of optical and near-infrared counterparts of binary neutron star mergers not only enrich our knowledge about the abundance of heavy elements in the universe and help reveal the remnant object just after the merger, which is generally known, but can also effectively constrain the dense properties of the nuc... | a bayesian inference of a relativistic mean-field model of neutron star matter from observations of nicer and gw170817/at2017gfo |
we analysed the thermal emission from the entire surface of the millisecond pulsar psr j0437-4715 observed in the ultraviolet and soft x-ray bands. for this, we calculated non-magnetized, partially ionized atmosphere models of hydrogen, helium, and iron compositions and included plasma frequency effects that may affect... | neutron star radius measurement from the ultraviolet and soft x-ray thermal emission of psr j0437-4715 |
neutron stars (ns)s are astrophysical objects with strong gravitational and electromagnetic fields. since there are several effects on radiation processes around the star, it is impossible to consider whole effects all together. one way to study the processes is by considering them one by one as a toy model. in this pa... | particle acceleration and electromagnetic field of deformed neutron stars |
the particle-in-cell (pic) method has been developed by oscar buneman, charles birdsall, roger w. hockney, and john dawson in the 1950s and, with the advances of computing power, has been further developed for several fields such as astrophysical, magnetospheric as well as solar plasmas and recently also for atmospheri... | pic methods in astrophysics: simulations of relativistic jets and kinetic physics in astrophysical systems |
high time resolution and accuracy are of critical importance in the studies of timing analysis and time delay localization of gamma-ray bursts (grbs), soft gamma-ray repeaters (sgrs) and pulsars. the gravitational wave high-energy electromagnetic counterpart all-sky monitor (gecam) consisting of two micro-satellites, g... | on-ground and on-orbit time calibrations of gecam |
in the present paper, we investigate the dynamics of magnetized particles around magnetically and electrically reissner-nordström (rn) black hole. the main idea of the work is to distinguish the effects of electric and magnetic charges of the rn black hole and spin of the rotating kerr black hole through the dynamics o... | distinguishing magnetically and electrically charged reissner-nordström black holes by magnetized particle motion |
initial distributions of pulsar periods and magnetic fields are essential components of multiple modern astrophysical models. not enough work has been done to properly constrain these distributions using direct measurements. here, we aim to fill this gap by rigorously analysing the properties of young neutron stars (ns... | initial periods and magnetic fields of neutron stars |
discoveries of rotating radio transients and fast radio bursts (frbs) in pulsar surveys suggest that more of such transient sources await discovery in archival data sets. here we report on a single-pulse search for dispersed radio bursts over a wide range of galactic latitudes (|b| < 60°) in data previously searched... | a search for rotating radio transients and fast radio bursts in the parkes high-latitude pulsar survey |
the dark matter particle explorer, a space-based high precision cosmic-ray detector, has just reported the new measurement of the total electron plus positron energy spectrum up to 4.6 tev. a notable feature in the spectrum is the spectral break at ∼0.9 tev, with the spectral index softening from -3.1 to -3.9. such a f... | explanation of the knee-like feature in the dampe cosmic {e}^{-}+{e}^{+} energy spectrum |
the neutron star interior composition explorer (nicer) has extensively monitored the 2019 august outburst of the 401 hz millisecond x-ray pulsar sax j1808.4-3658. in this letter, we report on the detection of a bright helium-fueled type i x-ray burst. with a bolometric peak flux of (2.3 ± 0.1) × 10-7 erg s-1 cm-2, this... | a nicer thermonuclear burst from the millisecond x-ray pulsar sax j1808.4-3658 |
plasma energization through magnetic reconnection in the magnetically dominated regime featured by low plasma beta ( β = 8 π n k t 0 / b 2 ≪ 1 ) and/or high magnetization ( σ = b 2 / ( 4 π n m c 2 ) ≫ 1 ) is important in a series of astrophysical systems such as solar flares, pulsar wind nebula, and relativistic jets f... | particle acceleration during magnetic reconnection in a low-beta pair plasma |
motivated by the recent discoveries that six ultraluminous x-ray sources (ulxs) are powered by highly super-eddington x-ray pulsars, we searched for additional pulsating ulx (pulx) candidates by identifying sources that exhibit long-term flux variability of at least an order of magnitude (a common feature seen in the s... | the hunt for pulsating ultraluminous x-ray sources |
we perform a bayesian analysis of neutrons star moment of inertia by utilizing the available gravitational-wave data from ligo/virgo (gw170817 and gw190425) and mass-radius measurements from the neutron star interior composition explorer (psr j0030+0415 and psr j0740 + 6620), incorporating the possible phase transition... | on the moment of inertia of psr j0737-3039 a from ligo/virgo and nicer |
aims: we report on the measurement and investigation of pulsed high-energy γ-ray emission from the vela pulsar, psr b0833-45, based on observations with the largest telescope of h.e.s.s., ct5, in monoscopic mode, and on data obtained with the fermi-lat.methods: data from 40.3 h of observations carried out with the h.e.... | first ground-based measurement of sub-20 gev to 100 gev γ-rays from the vela pulsar with h.e.s.s. ii |
in the present paper we derive strong constrains on scalarization in scalar-gauss-bonnet (sgb) gravity using observations of pulsars in close binary systems. since scalarized neutron stars carry a nonzero scalar change, they emit scalar dipole radiation while inspiraling which speeds up the orbital decay. the observati... | constraining scalarization in scalar-gauss-bonnet gravity through binary pulsars |
we study the possibility of probing new physics accounting for $(g-2)_\mu$ anomaly and gravitational waves with pulsar timing array measurements. the model we consider is either a light gauge boson or neutral scalar interacting with muons. we show that the parameter spaces of dark $u(1)$ model with kinetic mixing expla... | probing new physics for $(g-2)_\\mu$ and gravitational waves |
the recent measurement by lhaaso of gamma-ray emission extending up to hundreds of tev from multiple galactic sources represents a major observational step forward in the search for the origin of the galactic cosmic rays. the burning question is if this ultra-high-energy emission is associated with the acceleration of ... | pulsar wind nebula origin of the lhaaso-detected ultra-high energy γ-ray sources |
tev halos are regions of enhanced photon emissivity surrounding pulsars. while multiple sources have been discovered, a self-consistent explanation of their radial profile and spherically symmetric morphology remains elusive due to the difficulty in confining high-energy electrons and positrons within ∼20 pc regions of... | anisotropic diffusion cannot explain tev halo observations |
the globular cluster 47 tucanae (47 tuc) is one of the most massive star clusters in the milky way and is exceptionally rich in exotic stellar populations. for several decades it has been a favorite target of observers, and yet it is computationally very challenging to model because of its large number of stars (n ≳ 10... | compact object modeling in the globular cluster 47 tucanae |
based on the accurately calibrated interaction fsugold, we show that including isovector-scalar δ meson and its coupling to isoscalar-scalar σ meson in the relativistic mean-field (rmf) model can soften the symmetry energy e sym(n) at intermediate densities while stiffening the e sym(n) at high densities. we find this ... | effects of isoscalar- and isovector-scalar meson mixing on neutron star structure |
in this work, we study variations in the parabolic scintillation arcs of the binary millisecond pulsar psr j1643-1224 over five years using the large european array for pulsars (leap). the two-dimensional (2d) power spectrum of scintillation, called the secondary spectrum, often shows a parabolic distribution of power,... | modelling annual scintillation arc variations in psr j1643-1224 using the large european array for pulsars |
aims: the usefulness and versatility of the psrsalsa open-source pulsar data-analysis project is demonstrated through an analysis of the radio pulsar b1839-04. this study focuses on the phenomenon of bi-drifting, an effect where the drift direction of subpulses is systematically different in different pulse profile com... | investigation of the bi-drifting subpulses of radio pulsar b1839-04 utilising the open-source data-analysis project psrsalsa |
the canadian hydrogen intensity mapping experiment (chime)/frb experiment has detected thousands of fast radio bursts (frbs) due to its sensitivity and wide field of view; however, its low angular resolution prevents it from localizing events to their host galaxies. very long baseline interferometry (vlbi), triggered b... | localizing frbs through vlbi with the algonquin radio observatory 10 m telescope |
we consider spherical exact models for compact stars with anisotropic pressures and a conformal symmetry. the conformal symmetry condition generates an integral relationship between the gravitational potentials. we solve this condition to find a new anisotropic solution to the einstein field equations. we demonstrate t... | spherical conformal models for compact stars |
libstempo uses the tempo2 library (ascl:1210.015) to load a pulsar's tim/par files, providing python access to the toas, the residuals, the timing-model parameters, the fit procedure, and more. | libstempo: python wrapper for tempo2 |
evidence for the presence of extra fields during inflation may be found in the anisotropies of the scalar and tensor spectra across a vast range of scales. indeed, beyond the single-field slow-roll paradigm, a long tensor mode modulating the power spectrum can induce a sizable quadrupolar anisotropy. we investigate how... | searching for fossil fields in the gravity sector |
while the majority of massive stars have a stellar companion, most pulsars appear to be isolated. taken at face value, this suggests that most massive binaries break apart due to strong natal kicks received in supernova explosions. however, the observed binary fraction can still be subject to strong selection effects, ... | gaia pulsars and where to find them |
we constrain the equation of state of quark stars within the bayesian statistical approach using the mass and radius measurements of psr j0030+0451 from nicer. three types of bag models, with and without non-zero finite quark mass and/or superfluidity, are employed for quark stars made up with self-bound strange quark ... | bayesian inference of quark star equation of state using the nicer psr j0030+0451 data |
events gw170817 and grb 170817a provide the best confirmation so far that compact binary mergers where at least one of the companions is a neutron star can be the progenitors of short gamma-ray bursts (sgrbs). an open question for gw170817 remains the values and impact of the initial neutron star spins. the initial spi... | effects of spin on magnetized binary neutron star mergers and jet launching |
some of the most energetic pulsars exhibit rotation-modulated γ-ray emission in the 0.1-100 gev band. the luminosity of this emission is typically 0.1%-10% of the pulsar spin-down power (γ-ray efficiency), implying that a significant fraction of the available electromagnetic energy is dissipated in the magnetosphere an... | magnetic energy dissipation and γ-ray emission in energetic pulsars |
the electrical asymmetry effect (eae) enables separate control of the ion flux and the mean ion energy in capacitively coupled plasmas (ccp). while a variety of plasma processing applications benefit from this, large-area, very-high-frequency ccps still suffer from lateral nonuniformities caused by electromagnetic stan... | suppression of nonlinear standing wave excitation via the electrical asymmetry effect |
we generate a new exact model for neutral anisotropic star using einstein field equations. in this model, we consider a quadratic equation of state (qeos) and a choice of gravitational potential which generalizes the choice formulated by pant and fuloria. we generate stellar masses consistent with previous findings whi... | a neutral stellar model with quadratic equation of state |
a new type of embedding class-i representing anisotropic fluid distribution is presented. the new solution is free from singularity and also satisfies all physical criteria. it also satisfies all energy conditions such as sec, wec, nec and dec. the solution so obtained is used to optimize mass and radius of some well c... | a new analytic solution representing anisotropic stellar objects in embedding class i |
the discovery of millisecond pulsars switching between states powered either by the rotation of their magnetic field or by the accretion of matter has recently proved the tight link shared by millisecond radio pulsars and neutron stars in low-mass x-ray binaries. transitional millisecond pulsars also show an enigmatic ... | a propeller model for the sub-luminous state of the transitional millisecond pulsar psr j1023+0038 |
pixel super-resolution (psr) techniques have been developed to overcome the sampling limit in lensless digital holographic imaging. however, the inherent non-convexity of the psr phase retrieval problem can potentially degrade reconstruction quality by causing the iterations to tend toward a false local minimum. furthe... | high-fidelity pixel-super-resolved complex field reconstruction via adaptive smoothing |
as the moon migrated away from earth, it experienced a major spin axis reorientation. permanently shadowed regions (psrs), which are thought to have trapped ices and are a main focus of lunar exploration, appeared and grew after this (cassini state) transition and are often younger than their host craters. here, we cal... | past extent of lunar permanently shadowed areas |
the sustainable development of sii (small inhabited islands) has critical impacts on human well-being and requires balancing complex multiobjectives, for which the most beneficial actions must be prioritized, with limited financial and labor support. the effect of current plans based on single-scale or single-objective... | developing a multiscale landscape assessment framework integrating multiobjectives to identify priority action plans for sustainable development of small inhabited islands |
we study spherically symmetric magnetically charged generic singular black hole solutions of general relativity coupled to nonlinear electrodynamics. for characteristic values of the generic spacetime parameters and the parameter characterizing the ratio of the gravitational and electromagnetic forces acting on an elec... | charged and magnetized particles motion in the field of generic singular black holes governed by general relativity coupled to nonlinear electrodynamics |
in this paper we show that the most luminous supernova discovered very recently, asassn-15lh, could have been powered by a newborn ultra-strongly magnetized pulsar, which initially rotates near the kepler limit. we find that if this pulsar is a neutron star, its rotational energy could be quickly lost as a result of gr... | the most luminous supernova asassn-15lh: signature of a newborn rapidly rotating strange quark star |
we consider a scenario with axions/axion-like particles chern-simons gravity coupling, such that gravitational waves can be produced directly from axion wave tachyonic instability in the early universe after inflation. this axion gravity term is less constrained compared to the well-searched axion photon coupling and c... | gravitational waves from axion wave production |
timing a pulsar orbiting around sagittarius a* (sgr a*) can provide us with a unique opportunity of testing gravity theories. we investigate the detectability of a vector charge carried by the sgr a* black hole (bh) in the bumblebee gravity model with simulated future pulsar timing observations. the spacetime of a bumb... | probing the vector charge of sagittarius a* with pulsar timing |
we investigate gravitational-wave backgrounds (gwbs) of primordial origin that would manifest only at ultra-high frequencies, from kilohertz to 100 gigahertz, and leave no signal at either ligo, einstein telescope, cosmic explorer, lisa, or pulsar-timing arrays. we focus on gwbs produced by cosmic strings and make pred... | ultra-high frequency primordial gravitational waves beyond the khz: the case of cosmic strings |
we present the analysis of 200-ks nustar observation of the vela pulsar and the pulsar wind nebula (pwn). the phase-resolved spectra corresponding to the two main peaks in the folded pulse profile differ significantly. the spectrum of peak 1 is significantly harder than that of peak 2 in qualitative agreement with the ... | nustar observation of the vela pulsar and its nebula |
the maxi/gsc nova-alert system (negoro et al. 2016) detected an x-ray brightening from the be/x-ray binary pulsar v 0332+53 (x0331+53) on 2017 january 21 (mjd 57774). | maxi/gsc detection of the outburst onset from be/x-ray binary pulsar v 0332+53 (x0331+53) |
pulsar magnetospheres are thought to be filled with electron-positron plasma generated in pair cascades. the driving mechanism of these cascades is the emission of gamma-ray photons and their conversion into pairs via quantum electrodynamics (qed) processes. in this work, we present 2d particle-in-cell simulations of p... | coherent emission from qed cascades in pulsar polar caps |
recently, evidence of stochastic gravitational wave background (sgwb) signals observed by pulsar timing array (pta) collaborations, has prompted investigations into their origins. we explore the compatibility of a proposed inflationary scenario, incorporating an intermediate null energy condition (nec)-violating phase,... | null energy condition violation during inflation and pulsar timing array observations |
pulsars are known for their exceptionally stable rotation. however, this stability can be disrupted by glitches, sudden increases in rotation frequency whose cause is poorly understood. in this study, we present some preliminary results from the pulsar monitoring campaign conducted at the iar since 2019. we present mea... | updates on the glitching pulsar monitoring campaign performed from iar |
recent detections of a low-frequency gravitational wave background (gwb) from various pulsar-timing-array (pta) observations have renewed the interest in the inspiraling supermassive black hole binaries (smbhbs), whose population is believed to be the most promising candidate of but disfavored by the observed gwb spect... | distinctive gwbs from eccentric inspiraling smbh binaries with a dm spike |
general relativity has been very successful since its proposal more a century ago. however, various cosmological observations and theoretical consistency still motivate us to explore extended gravity theories. horndeski gravity stands out as one attractive theory by introducing only one scalar field. here we formulate ... | post-newtonian binary dynamics in effective field theory of horndeski gravity |
the discovery of gravitational waves (gws) opens a new window for exploring the physics of the early universe. identifying the source of gws and their spectra today turn out to be the important tasks so as to assist the experimental detection of stochastic gws. in this paper, we investigate the oscillations of the ultr... | oscillations of ultralight dark photon into gravitational waves |
the recent analysis on the central compact object in the hess j1731-347 remnant suggests interestingly small values for its mass and radius. such an observation favors soft nuclear models that may be challenged by the observation of massive compact stars. in contrast, the recent prex-ii experiment, concerning the neutr... | hybrid stars in light of the hess j1731-347 remnant and the prex-ii experiment |
it has been suggested that the gev excess, observed from the region surrounding the galactic center, might originate from a population of millisecond pulsars that formed in globular clusters. with this in mind, we employ the publicly available fermi data to study the gamma-ray emission from 157 globular clusters, ident... | the gamma-ray pulsar population of globular clusters: implications for the gev excess |
we report on a comprehensive multiwavelength study of the pulsars in the globular cluster (gc) m5, including the discovery of m5g, a new compact noneclipsing "black widow" pulsar. thanks to the analysis of 34 yr of radio data taken with the five-hundred-meter aperture spherical radio telescope and arecibo telescopes, w... | discovery and timing of millisecond pulsars in the globular cluster m5 with fast and arecibo |
the cherenkov telescope array (cta) is a next-generation ground-based observatory for gamma-ray astronomy at very high energies. the large-sized telescope prototype (lst-1) is located at the cta-north site, on the canary island of la palma. lsts are designed to provide optimal performance in the lowest part of the ener... | observations of the crab nebula and pulsar with the large-sized telescope prototype of the cherenkov telescope array |
cosi is a smex mission that provides a significant improvement in 0.2-5 mev sensitivity along with high-resolution spectroscopy, enabling studies of 511 kev positron annihilation emission and measurements of radioactive elements. cosi measures polarization of grbs, accreting black holes, and pulsars as well as localizi... | the compton spectrometer and imager |
black hole-neutron star (bhns) mergers are one of the most promising targets for multimessenger astronomy. using general relativistic magnetohydrodynamic simulations of bhns undergoing merger we previously showed that a magnetically driven jet can be launched by the disk +spinning black hole remnant if the neutron star... | jet launching from binary black hole-neutron star mergers: dependence on black hole spin, binary mass ratio, and magnetic field orientation |
ultraluminous x-ray (ulx) pulsars are a new class of object powered by apparent super-critical accretion onto magnetized neutron stars. three sources in this class have been identified so far; m82 x-2, ngc 5907 ulx-1, and ngc 7793 p13 have been found to have two properties in common; ∼1 s spin periods, and for ngc 5907... | a ∼60 day super-orbital period originating from the ultraluminous x-ray pulsar in m82 |
xte j1810-197 (psr j1809-1943) was the first magnetar that was found to emit transient radio emission. it has recently undergone another radio and high-energy outburst. this is only the second radio outburst that has been observed from this source. we observed j1810-197 soon after its recent radio outburst at low radio... | distinct properties of the radio burst emission from the magnetar xte j1810-197 |
we explore the possibility that the observed population of galactic hypervelocity stars (hvss) originate as runaway stars from the large magellanic cloud (lmc). pairing a binary evolution code with an n-body simulation of the interaction of the lmc with the milky way, we predict the spatial distribution and kinematics ... | hypervelocity runaways from the large magellanic cloud |
while theoretical models of dust condensation predict that most refractory elements produced in core-collapse supernovae (sne) efficiently condense into dust, a large quantity of dust has so far only been observed in sn 1987a. we present an analysis of observations from the spitzer space telescope, herschel space obser... | a massive shell of supernova-formed dust in snr g54.1+0.3 |
in this study we demonstrate that general relativity predicts arrival time differences between gravitational wave (gw) and electromagnetic (em) signals caused by the wave effects in gravitational lensing. the gw signals can arrive earlier than the em signals in some cases if the gw/em signals have passed through a lens... | arrival time differences between gravitational waves and electromagnetic signals due to gravitational lensing |
gravitational waves (gws) are a new avenue of observing our universe. so far, we have seen them in the ~10-100 hz range, and there are hints that we might soon detect them in the nanohertz regime. multiple efforts are underway to access gws across the frequency spectrum; however, parts of the frequency space are curren... | gravitational wave detection with relative astrometry using roman's galactic bulge time domain survey |
the nature of gw190814's secondary component m2 of mass 2.50-2.67 m⊙ in the mass gap between the currently known maximum mass of neutron stars and the minimum mass of black holes is currently under hot debate. among the many possibilities proposed in the literature, m2 was suggested to be a superfast pulsar, while its ... | r-mode stability of gw190814's secondary component as a supermassive and superfast pulsar |
we conduct searches for continuous gravitational waves from seven pulsars that have not been targeted in continuous wave searches of advanced ligo data before. we target emission at exactly twice the rotation frequency of the pulsars and in a small band around such a frequency. the former search assumes that the gravit... | new searches for continuous gravitational waves from seven fast pulsars |
we have measured the scattering time-scale, τ, and the scattering spectral index, α, for 84 single-component pulsars. observations were carried out with the meerkat telescope as part of the thousand-pulsar-array programme in the meertime project at frequencies between 0.895 and 1.670 ghz. our results give a distributio... | the thousand-pulsar-array programme on meerkat - v. scattering analysis of single-component pulsars |
neutrons were discovered 90 years ago by james chadwick. the concept of neutron stars was hypothesized around that time by lev landau, walter baade, and fritz zwicky, and it was further developed by richard tolman, robert oppenheimer, george volkoff, and other physicists. neutron stars are astrophysical compact objects... | neutron stars as extreme laboratories for gravity tests |
we present the sarao meerkat galactic plane survey (smgps), a 1.3 ghz continuum survey of almost half of the galactic plane (251°$\le l \le$ 358°and 2°$\le l \le$ 61°at $|b| \le 1.5°$). smgps is the largest, most sensitive and highest angular resolution 1 ghz survey of the plane yet carried out, with an angular resolut... | the sarao meerkat 1.3 ghz galactic plane survey |
cosmic-ray positrons have long been considered a powerful probe of dark matter annihilation. in particular, myriad studies of the unexpected rise in the positron fraction have debated its dark matter or pulsar origins. in this paper, we instead examine the potential for extremely precise positron measurements by ams-02... | cosmic-ray positrons strongly constrain leptophilic dark matter |
in this paper, we assess different charged self-gravitating stellar models possessing anisotropic matter source in the background of $f(g,t)$ gravity. for this purpose, we choose a well-known model of this gravity, i.e., $f(g,t)=g^2+\varrho t$, where $\varrho$ stands for the coupling constant. the modified field equati... | study of charged celestial objects in modified gravity |
the detection of nanohertz gravitational waves through pulsar timing arrays hinges on identifying a common stochastic process affecting all pulsars in a correlated way across the sky. in the presence of other deterministic and stochastic processes affecting the time-of-arrival of pulses, a detection claim must be accom... | posterior predictive checking for gravitational-wave detection with pulsar timing arrays. ii. posterior predictive distributions and pseudo-bayes factors |
in this paper, we investigate the properties of anisotropic, spherically symmetric compact stars, especially, electrically charged strange stars in f(q) symmetric teleparallel gravity. those stars are hypothesized to be composed of strange quark matter, whose distribution is controlled by the mit-bag model equation of ... | anisotropic electrically charged stars in f(q) symmetric teleparallel gravity |
the shapes of galaxies trace scalar physics in the late-universe through the large-scale gravitational potential. are they also sensitive to higher-spin physics? we present a general study into the observational consequences of vector and tensor modes in the early and late universe, through the statistics of cosmic she... | what can galaxy shapes tell us about physics beyond the standard model? |
we propose a new stellar structure of compact stars, the "cross stars" that consist of a hadronic matter core and a quark matter crust, with an inverted structure compared to the conventional hybrid stars. this distinct stellar structure naturally arises from the quark matter to hadronic matter transition associated wi... | hybrid stars may have an inverted structure |
astrometry holds the potential for testing fundamental physics through the effects of the stochastic gravitational wave background (sgwb) in the $\sim 1-100$ nhz frequency band on precision measurements of stellar positions. such measurements are complementary to tests made possible by the detection of the sgwb using p... | probing parity violation in the stochastic gravitational wave background with astrometry |
observations of accreting neutron stars (nss) with strong magnetic fields can be used not only for studying the accretion flow interaction with the ns magnetospheres, but also for understanding the physical processes inside nss and for estimating their fundamental parameters. of particular interest are (i) the interact... | the x-ray properties of be/x-ray pulsars in quiescence |
more than 100 millisecond pulsars (msps) have been discovered in radio observations of gamma-ray sources detected by the fermi large area telescope (lat), but hundreds of pulsar-like sources remain unidentified. here, we present the first results from the targeted survey of fermi-lat sources being performed by the tran... | the trapum l-band survey for pulsars in fermi-lat gamma-ray sources |
statistical anisotropy in the nanohertz-frequency gravitational wave background (gwb) is expected to be detected by pulsar timing arrays (ptas) in the near future. by developing a frequentist statistical framework that intrinsically restricts the gwb power to be positive, we establish scaling relations for multipole-de... | forecasting pulsar timing array sensitivity to anisotropy in the stochastic gravitational wave background |
we present the first large sample of scintillation arcs in millisecond pulsars (msps), analysing 12 sources observed with the large european array for pulsars (leap), and the effelsberg 100-m telescope. we estimate the delays from multipath propagation, measuring significant correlated changes in scattering time-scales... | variable scintillation arcs of millisecond pulsars observed with the large european array for pulsars |
we report on radio timing observations of psr j0210+5845 which reveal large deviations from typical pulsar spin-down behaviour. we interpret these deviations as being due to binary motion around the $v=13.5$ star 2mass j02105640$+$5845176, which is coincident in celestial position and distance with the pulsar. archival... | psr j0210+5845; an ultra wide binary pulsar with a b6v main-sequence star companion |
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