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we discuss the prospects for identifying the nearest isolated black holes (ibhs) in our galaxy. ibhs accreting gas from the interstellar medium likely form magnetically arrested disks (mads). we show that thermal electrons in the mads emit optical signals through the thermal synchrotron process while nonthermal electro... | multiwavelength emission from magnetically arrested disks around isolated black holes |
observations of galactic white dwarfs with gaia have allowed for unprecedented modelling of white dwarf cooling, resolving core crystallization, and sedimentary heating from neutron-rich nuclei. these cooling sequences are sensitive to the diffusion coefficients of nuclei in coulomb plasmas which have order 10 per cent... | precise diffusion coefficients for white dwarf astrophysics |
the onset of s10 proton spin-singlet pairing in neutron-star matter is studied in the framework of the bcs theory including medium polarization effects. the strong three-body coupling of the diproton pairs with the dense neutron environment and the bcs self-energy effects severely reduce the gap magnitude, so to reshap... | proton-proton s10 pairing in neutron stars |
strongly magnetized isolated neutron stars (nss) are categorized into two families, according mainly to their magnetic field strength. those with a higher magnetic field of 1014-1015 g are called magnetars, characterized by repeated short bursts, and the others are x-ray isolated neutron stars (xinss) with 1013 g. both... | universal detection of high-temperature emission in x-ray isolated neutron stars |
about 10% of the massive main sequence stars have recently been found to host a strong, large scale magnetic field. both, the origin and the evolutionary consequences of these fields are largely unknown. we argue that these fields may be sufficiently strong in the deep interior of the stars to suppress convection near ... | blue supergiants as descendants of magnetic main sequence stars |
the persistent thermal luminosity of magnetars and their outbursts suggest the existence of some internal heat sources located in their outer crust. the compression of matter accompanying the decay of the magnetic field may trigger exothermic electron captures and, possibly, pycnonuclear fusions of light elements that ... | heating in magnetar crusts from electron captures |
evidence has accumulated for an as-yet unaccounted for source of heat located at shallow depths within the accreted neutron star crust. however, the nature of this heat source is unknown. i demonstrate that the inferred depth of carbon ignition in x-ray superbursts can be used as an additional constraint for the magnit... | constraining accreted neutron star crust shallow heating with the inferred depth of carbon ignition in x-ray superbursts |
it was pointed out in a recent paper that the observed cooling rate of old, cold neutron stars (ns) can provide an upper limit on the transition rate of neutron to mirror neutron (n -n' ). this limit is so stringent that it would preclude any discovery of n →n' oscillation in the current round of terrestrial searches f... | neutron-mirror-neutron oscillation and neutron star cooling |
modeling of crust heating and cooling across multiple accretion outbursts of the low mass x-ray binary mxb 1659-29 indicates that the neutrino luminosity of the neutron star core is consistent with direct urca (durca) reactions occurring in ~1% of the core volume. we investigate this scenario with neutron star models t... | fast neutrino cooling in the accreting neutron star mxb 1659-29 |
we study a class of dfsz-like models for the qcd axion that can address observed anomalies in stellar cooling. stringent constraints from sn1987a and neutron stars are avoided by suppressed couplings to nucleons, while axion couplings to electrons and photons are sizable. all axion couplings depend on few parameters th... | flavor-violating higgs decays and stellar cooling anomalies in axion models |
based on the oscillation between the b phase and a phase of 3p2 neutron superfluid in neutron stars, we propose a new glitch model for young pulsars. according to our model, the glitch is explained as a repeat phenomena from the quasi period 3p2 neutron superfluid b phase, to a phase, then to b phase (many repeated gli... | new insight into the physical essence of pulsar glitch |
in this lecture i will briefly review some of the effects of hyperons on the properties of neutron and proto-neutron stars. in particular, i will revise the problem of the strong softening of the eos, and the consequent reduction of the maximum mass, induced by the presence of hyperons, a puzzle which has become more i... | hyperons and neutron stars |
circulating tumor cells (ctcs) have become an established biomarker for prognosis in patients with various carcinomas. however, current ex vivo ctc isolation technologies rely on small blood volumes from a single venipuncture limiting the number of captured ctcs. this produces statistical variability and inaccurate ref... | a temporary indwelling intravascular aphaeretic system for in vivo enrichment of circulating tumor cells |
we study the thermal evolution of neutron stars containing deconfined quark matter in their core. such objects are generally referred to as quark-hybrid stars. the confined hadronic matter in their core is described in the framework of nonlinear relativistic nuclear field theory. for the quark phase we use a nonlocal e... | thermal evolution of hybrid stars within the framework of a nonlocal nambu-jona-lasinio model |
newborn, strongly magnetized neutron stars (so-called magnetars) surrounded by their stellar or merger ejecta are expected to be sources of ultrahigh-energy neutrinos via decay of mesons produced in hadronic interactions of protons which are accelerated to ultrahigh energies by magnetic dissipation of the spindown ener... | charm contribution to ultrahigh-energy neutrinos from newborn magnetars |
background: superfluidity in the crust is a key ingredient for the cooling properties of proto-neutron stars. present theoretical calculations employ the quasiparticle mean-field hartree-fock-bogoliubov theory with temperature-dependent occupation numbers for the quasiparticle states. purpose: finite temperature stella... | heat capacity of the neutron star inner crust within an extended nuclear statistical equilibrium model |
the fermi surface depletion of beta-stable nuclear matter is calculated to study its effects on several physical properties that determine the neutron star (ns) thermal evolution. the neutron and proton z factors measuring the corresponding fermi surface depletions are calculated within the brueckner-hartree-fock appro... | role of nucleonic fermi surface depletion in neutron star cooling |
we investigate the spectral and timing properties of the millihertz quasi-periodic oscillations (mhz qpos) in neutron-star low-mass x-ray binary 4u 1636-53 using xmm-newton and rossi x-ray timing explorer (rxte) observations. the mhz qpos in the xmm-newton/rxte observations show significant frequency variation and disa... | spectral and timing analysis of the mhz qpos in the neutron-star low-mass x-ray binary 4u 1636-53 |
we use the bayesian approach to write the posterior probability density for the three-dimensional velocity of a pulsar and for its kinematic age. as a prior, we use the bimodal velocity distribution found in a recent article by verbunt, igoshev & cator. when we compare the kinematic ages with spin-down ages we find... | ages of radio pulsar: long-term magnetic field evolution |
nuclear reactions heat and cool the crust of accreting neutron stars and need to be understood to interpret observations of x-ray bursts and long-term cooling in transiently accreting systems. it was recently suggested that previously ignored neutron transfer reactions may play a significant role in the nuclear process... | the impact of neutron transfer reactions on the heating and cooling of accreted neutron star crusts |
the long-period (p = 1091 s) of the recently discovered pulsar gleam-x j162759.5-523504.3 can be attained by neutron stars evolving with fallback discs and magnetic dipole moments of a few 1030 g cm3 at ages greater than ~2 × 105 yr consistently with the observational upper limits to the period derivative, $\dot{p}$, a... | evolution of the long-period pulsar gleam-x j162759.5-523504.3 |
in this work, we reinvestigate the electron fraction $y_{e}$ and electron fermi energy $e_{f}(e)$ of neutron stars, based on our previous work of li et al.(2016), in which we firstly deduced a special solution to $e_{f}(e)$, and then obtained several useful analytical formulae for $y_{\rm e}$ and matter density $\rho$ ... | reinvestigation of the electron fraction and electron fermi energy of neutron star |
valuable information about the neutron star (ns) interior can be obtained by comparing observations of thermal radiation from a cooling ns crust with theoretical models. nuclear burning of lighter elements that diffuse to deeper layers of the envelope can alter the relation between surface and interior temperatures and... | the effect of diffusive nuclear burning in neutron star envelopes on cooling in accreting systems |
a review of wind accretion in high-mass x-ray binaries is presented. we focus on different regimes of quasi-spherical accretion onto the neutron star (ns): the supersonic (bondi) accretion, which takes place when the captured matter cools down rapidly and falls supersonically towards the ns magnetosphere, and subsonic ... | wind accretion: theory and observations |
the application of standard accretion theory to observations of x-ray binaries provides valuable insights into neutron star (ns) properties, such as their spin period and magnetic field. however, most studies concentrate on relatively old systems, where the ns is in its late propeller, accretor, or nearly spin equilibr... | early neutron star evolution in high-mass x-ray binaries |
we report that the rs cvn-type star gt mus (hr 4492, hd 101379+hd 101380) was the most active star in the x-ray sky in the last decade in terms of the scale of recurrent energetic flares. we detected 11 flares from gt mus in 8 yr of observations with the monitor of all-sky x-ray image (maxi) from 2009 august to 2017 au... | the rs cvn-type star gt mus shows most energetic x-ray flares throughout the 2010s |
we discuss the effect of convection driven by chemical separation at the ocean-crust boundary of accreting neutron stars. we extend the steady-state results of medin & cumming to transient accretors, by considering the time-dependent cases of heating during accretion outbursts and cooling during quiescence. during ... | time-dependent, compositionally driven convection in the oceans of accreting neutron stars |
accreting neutron stars (ns) can exhibit high frequency modulations in their lightcurves during thermonuclear x-ray bursts, known as burst oscillations. these frequencies can be offset from the ns spin frequency by several hz (where known independently) and can drift by 1-3 hz. one plausible explanation is that a wave ... | relativistic ocean r-modes during type-i x-ray bursts |
designs for future gravitational wave detection facilities feature silicon test masses at cryogenic temperatures to reduce thermal noise and thermally induced aberrations. designers call for operation at 123 k or close to 18 k to exploit the vanishing thermal expansion of crystalline silicon. the amount of absorbed hea... | practical test mass and suspension configuration for a cryogenic kilohertz gravitational wave detector |
previous optical and radio observations of the binary millisecond pulsar psr j1640+2224 have come to inconsistent conclusions about the identity of its companion, with some observations suggesting that the companion is a low-mass helium-core (he-core) white dwarf (wd), while others indicate that it is most likely a hig... | reconciling optical and radio observations of the binary millisecond pulsar psr j1640+2224 |
we study the effects of heat blanketing envelopes of neutron stars on their cooling. to this aim, we perform cooling simulations using newly constructed models of the envelopes composed of binary ion mixtures (h-he, he-c, c-fe) varying the mass of lighter ions (h, he or c) in the envelope. the results are compared with... | cooling of neutron stars with diffusive envelopes |
context. an increasing number of low-mass (m⋆/m⊙ ≲ 0.45) and extremely low-mass (elm, m⋆/m⊙ ≲ 0.18-0.20) white-dwarf stars are being discovered in the field of the milky way. some of these stars exhibit long-period g-mode pulsations, and are called elmv variable stars. also, some low-mass pre-white dwarf stars show sho... | pulsating low-mass white dwarfs in the frame of new evolutionary sequences. iv. the secular rate of period change |
we report the discovery of the isolated neutron star (ins) candidates erassu j065715.3+260428 and erassu j131716.9−402647 from the spectrum roentgen gamma (srg) erosita all-sky survey. selected for their soft x-ray emission and absence of catalogued counterparts, both objects were recently targeted with the large binoc... | discovery of two promising isolated neutron star candidates in the srg/erosita all-sky survey |
the structure and composition of the crust of neutron stars plays an important role in their thermal and magnetic evolution, hence in setting their observational properties. one way to study the properties of the crust of a neutron star, is to measure how it cools after it has been heated during an accretion outburst i... | crust cooling of the neutron star in aql x-1: different depth and magnitude of shallow heating during similar accretion outbursts |
in this work, we shortly review the role and properties of hyperons in finite and infinite nuclear systems such as hypernuclei and neutron stars. particularly, we describe different production mechanisms of hypernuclei, discuss some aspects of their γ-ray spectroscopy and their weak decay modes, and give a few strokes ... | hyperons in finite and infinite nuclear systems |
we perform 2d axisymmetric radiative relativistic mhd simulations of radiation pressure supported neutron star accretion columns in split-monopole magnetic fields. the accretion columns exhibit quasi-periodic oscillations, which manifest in the luminosity power spectrum as 2-10 khz peaks, together with broader extensio... | dynamics of neutron star accretion columns in split-monopole magnetic fields |
disk accretion at a high rate onto a white dwarf (wd) or a neutron star has been suggested to result in the formation of a spreading layer (sl)—a belt-like structure on the object's surface, in which the accreted matter steadily spreads in the poleward (meridional) direction while spinning down. to assess its basic cha... | spreading layers in accreting objects: role of acoustic waves for angular momentum transport, mixing, and thermodynamics |
based on the linear-mixing approach, we calculate the latent heat for crystallizing fully ionized 12c/16o and 16o/20ne mixtures in white dwarf (wd) cores for two different parametrizations of the corrections to the linear-mixing energies and with account of ion quantum effects. we report noticeable composition-dependen... | on excess entropy and latent heat in crystallizing white dwarfs |
new shell-model hamiltonians which can successfully describe spin responses in nuclei are used to evaluate nuclear weak rates in stellar environments. the e-capture and β-decay rates for the nuclear pair with 31mg-31al, in the island of inversion, which have been pointed out to be important for the cooling of neutron s... | shell-model study of nuclear weak rates relevant to astrophysical processes in stars |
we model the quiescent luminosity of accreting neutron stars with several equation of states (eoss), including the effect of pion condensation and superfluidity. as a consequence of comparison with the observations, we show that the results with togashi eos (the strong direct urca process is forbidden) and tm1e eos (ma... | quiescent luminosities of accreting neutron stars with different equation of states |
the nuclear symmetry energy and its behavior with density has been recently evaluated with enhanced value by prex-2 experiment. this new values enables direct urca neutrino emission process to be functioning in the dense matter inside neutron stars. with this new outlook we study the cooling rate of canonical mass neut... | fast neutron star cooling in light of the prex-2 experiment |
the presence of strong magnetic fields in neutron stars, such as in magnetars, may significantly affect their crust-core transition properties and the crust size. this knowledge is crucial in the correct interpretation of astrophysical phenomena involving magnetars, such as glitches in observed rotation frequencies, co... | estimating magnetar radii with an empirical meta-model |
in this work, we revisit the thermal relaxation process for neutron stars. such a process is associated with the thermal coupling between the core and the crust of neutron stars. the thermal relaxation, which takes place at around 10-100 years, is manifested as a sudden drop in the star's surface temperature. such a dr... | revisiting the thermal relaxation of neutron stars |
the be/x-ray transient gro j1750-27 exhibited a type-ii (giant) outburst in 2015. after the source transited to quiescence, we triggered our multi-year chandra monitoring programme to study its quiescent behaviour. the programme was designed to follow the cooling of a potentially heated neutron-star crust due to accret... | quiescent x-ray variability in the neutron star be/x-ray transient gro j1750-27 |
we report on the results of a ∼40-d multi-wavelength monitoring of the be x-ray binary system igr j05007-7047 (lxp 38.55). during that period the system was monitored in the x-rays using the swift telescope and in the optical with multiple instruments. when the x-ray luminosity exceeded 1036 erg s-1 we triggered an xmm... | multi-wavelength properties of igr j05007-7047 (lxp 38.55) and identification as a be x-ray binary pulsar in the lmc |
the code harm\_cool, a conservative scheme for relativistic magnetohydrodynamics, is being developed in our group and works with a tabulated equation of state of dense matter. this eos can be chosen and used during dynamical simulation, instead of the simple ideal gas one. in this case, the inversion scheme between the... | neutrino cooled disk in post-merger system studied via numerical gr mhd simulation with a composition-dependent equation of state |
we investigate the gravitational waves (gws) at low frequencies produced by neutrinos that are emitted anisotropically from the protoneutron star (pns) during its cooling phase that lasts for about a minute. we are particularly interested in the deci-hz range, in which some satellite-borne detectors are expected to hav... | gravitational wave signals in the deci-hz range from neutrinos during the protoneutron star cooling phase |
the gravitational instability, responsible for the formation of the structure of the universe, occurs below energy thresholds and above spatial scales of a self-gravitating expanding region, when thermal energy can no longer counterbalance self-gravity. i argue that at sufficiently-large scales, dark energy may restore... | the gravothermal instability at all scales: from turnaround radius to supernovae |
accreting neutron stars (nss) can exhibit high-frequency modulations, known as burst oscillations, in their light curves during thermonuclear x-ray bursts. their frequencies can be offset from the spin frequency of the ns (known independently) by several hz, and can drift by 1-3 hz. one plausible explanation for this p... | burning in the tail: implications for a burst oscillation model |
late activity of the central engine is often invoked in order to explain the flares observed in the early x-ray afterglow of gamma-ray bursts, either in the form of an active neutron star remnant or (fall-back) accretion on to a black hole. however, these scenarios are not always plausible, in particular when flares ar... | late x-ray flares from the interaction of a reverse shock with a stratified ejecta in grb afterglows: simulations on a moving mesh |
we study properties of an accretion ring in a steady mass flow from a companion star to a compact object in an x-ray binary. the accretion ring is a place where matter inflowing from a companion star sojourns for a while to bifurcate to accretion and excretion flows due to angular momentum transfer. the matter in the a... | properties of the accretion ring in an x-ray binary, and accretion and excretion two-layer flows from it |
superbursts are hours-long x-ray flares attributed to the thermonuclear runaway burning of carbon-rich material in the envelope of accreting neutron stars. by studying the details of the x-ray light curve, properties of carbon combustion can be determined. in particular, we show that the shape of the rise of the light ... | the imprint of carbon combustion on a superburst from the accreting neutron star 4u 1636-536 |
sax j1810.8-2609 is a faint x-ray transient, mostly known for its low quiescent thermal luminosity, which disagrees with slow cooling in the core. it is also one of a small sample of stars with a mass and radius that has been estimated using spectral modeling of one of its thermonuclear bursts. here we report the disco... | a millisecond oscillation in the bursting x-ray flux of sax j1810.8-2609 |
coherent oscillations and the evolution of the x-ray spectrum during thermonuclear x-ray bursts in accreting neutron-star x-ray binaries have been studied intensively but separately. we analysed all the x-ray bursts of the source 4u 1728-34 with the rossi x-ray timing explorer. we found that the presence of burst oscil... | the link between coherent burst oscillations, burst spectral evolution and accretion state in 4u 1728-34 |
a rapidly spinning, strongly magnetized neutron star (ns) is invoked as the central engine for some gamma-ray bursts (grbs), especially, the `internal plateau' feature of x-ray afterglow. however, for these `internal plateau' grbs, how to produce their prompt emission remains an open question. two different physical pr... | the radiative efficiency of relativistic jet and wind: a case study of grb 070110 |
type i x-ray bursts on the surface of a neutron star are a unique probe into accretion in x-ray binary systems. however, we know little about the feedback of the burst emission on accretion. hard x-ray shortages and enhancements of the persistent emission at soft x-rays have been observed. to put these findings in cont... | diagnosing the burst influence on accretion in the clocked burster gs 1826-238 |
the be/x-ray transient 4u 0115+63 exhibited a giant, type-ii outburst in 2015 october. the source did not decay to its quiescent state but settled in a meta-stable plateau state (a factor ∼ 10 brighter than quiescence) in which its luminosity slowly decayed. we used xmm-newton to observe the system during this phase an... | the low-luminosity behaviour of the 4u 0115+63 be/x-ray transient |
although accretion disc coronae appear to be common in many accreting systems, their fundamental properties remain insufficiently understood. recent work suggests that type i x-ray bursts from accreting neutron stars provide an opportunity to probe the characteristics of coronae. several studies have observed hard x-ra... | cooling of accretion disc coronae by type i x-ray bursts |
the magnetic field of a rotating pulsar might be so strong that the equation of state (eos) of neutron star (ns) matter is significantly affected by the spin polarization of baryons. in the present work, the eos of the spin-polarized nuclear matter is investigated in the nonrelativistic hartree-fock formalism, using a ... | spin-polarized β -stable neutron star matter: the nuclear symmetry energy and gw170817 constraint |
extremely compact objects trap gravitational waves or neutrinos, assumed to move along null geodesics in the trapping regions. the trapping of neutrinos was extensively studied for spherically symmetric extremely compact objects constructed under the simplest approximation of the uniform energy density distribution, wi... | neutrino trapping in extremely compact tolman vii spacetimes |
we study heat diffusion after an energy release in a deep spherical layer of the outer neutron star crust (107 ≲ ρ ≲ 4 × 1011 g cm-3). we demonstrate that this layer possesses specific heat-accumulating properties, absorbing heat and directing it mostly inside the star. it can absorb up to ∼1043-1044 erg due to its hig... | model of heat diffusion in the outer crust of bursting neutron stars |
high-velocity neutron stars (hvnss) that were kicked out from their birth location can be potentially identified with their large proper motions, and possibly with large parallax, when they come across the solar neighborhood. in this paper, we study the feasibility of hunting isolated hvnss in wide-area optical surveys... | hunting wide-area optical surveys for high proper motion isolated neutron stars |
the aim of this study was to perform sensitivity analysis, investigating how different fluidisation and sedimentation characteristics of three-phase wetted uo2 powder beds, may affect a transient nuclear criticality excursion initiated through the addition of water into a fissile powder bed. this type of postulated nuc... | transient nuclear criticality excursion analysis of highly dispersed particulate three-phase fluidised systems |
we report a 72 ks xmm-newton observation of the be/x-ray pulsar (bexrp) rx j0812.4-3114 in quiescence (l_x ≈ 1.6× 10^{33} erg s^{-1}). intriguingly, we find a two-component spectrum, with a hard power-law (γ ≈ 1.5) and a soft blackbody-like excess below ≈1 kev. the blackbody component is consistent in kt with a prior q... | soft excess in the quiescent be/x-ray pulsar rx j0812.4-3114 |
recent observational data on transiently-accreting neutron stars has unequivocally shown fast-cooling sources, such as in the case of neutron star mxb 1659-29. previous calculations have estimated its total neutrino luminosity and heat capacity, as well as suggested that direct urca reactions take place in $1 \%$ of th... | probing dense matter physics with transiently-accreting neutron stars: the case of source mxb 1659-29 |
we analyse and determine the effects of modest progenitor rotation in the context of core-collapse supernovae by comparing two separate long-duration three-dimensional simulations of 9 m$_{\odot}$ progenitors, one rotating with an initial spin period of $\sim$60 seconds and the other non-rotating. we determine that bot... | the physical effects of progenitor rotation: comparing two long-duration 3d core-collapse supernova simulations |
astrophysicists have found the first direct evidence for the fastest neutrino-emission mechanism by which neutron stars can cool. | a rapidly cooling neutron star |
the accretion behaviour in low-mass x-ray binaries (lmxbs) at low luminosities, especially at <1034 erg s-1, is not well known. this is an important regime to study to obtain a complete understanding of the accretion process in lmxbs, and to determine if systems that host neutron stars with accretion-heated crusts c... | uv and x-ray observations of the neutron star lmxb exo 0748-676 in its quiescent state |
in the present work, we used five different versions of the quark-meson coupling (qmc) model to compute astrophysical quantities related to the gw170817 event and the neutron star cooling process. two of the models are based on the original bag potential structure and three versions consider a harmonic oscillator poten... | neutron star cooling and gw170817 constraint within quark-meson coupling models |
axial anomalous contributions into neutrino pbf losses due to triplet pairing of neutrons are still ignored in modeling the evolution of neutron stars. in this paper, the influence of the anomalous axial contributions onto the rate of neutron stars cooling is estimated. | on the pbf neutrino losses in superfluid cores of neutron stars |
an efficient panchromatic planar perovskite solar cell is developed based on highly uniform, lead-reduced ch3nh3sn0.5pb0.5i3 perovskite films with full film-coverage on the substrates. we demonstrate here that full-coverage of the ch3nh3sn0.5pb0.5i3 films can be developed by a facile chlorobenzene-assisted spin-coating... | highly compact and uniform ch3nh3sn0.5pb0.5i3 films for efficient panchromatic planar perovskite solar cells |
we study the thermal evolution of neutron stars in the presence of hyperons or kaons in the core. our results indicate that the nucleon and the hyperon direct urca processes play crucial roles for macroscopic cooling behavior of neutron stars. the presence of hyperons drives fast cooling mechanisms in two ways: 1) it a... | strangeness in neutron star cooling |
we construct the quiescent neutron star models in the evolutionary calculations. the x-ray luminosities have been derived in terms of the time-averaged mass accretion rate for various neutron star masses and surface compositions. we compare the quiescent luminosities observed from x-ray transients in low mass x-ray bin... | quiescent luminosities of accreting neutron stars-possibility of neutrino losses due to strong pion condensations |
after an introduction to the qcd phase diagram, the nuclear equations of state, and neutron star mergers, i discuss three projects related to transport and nuclear matter in neutron star mergers. the first is the nature of beta equilibrium in the portion of a merger that is transparent to neutrinos. we calculate the we... | transport in neutron star mergers |
we find that the proton separation energy, s (p ) , of 73rb is -640 (40 ) kev, deduced from the observation of β -delayed ground-state protons following the decay of 73sr. this lower-limit determination of the proton separation energy of 73rb coupled with previous upper limits from nonobservation, provides a full const... | influence of 73rb on the ashes of accreting neutron stars |
we develop a multicomponent hydrodynamic model based on moments of the born-bogolyubov-green-kirkwood-yvon hierarchy equations for physical conditions relevant to astrophysical plasmas. these equations incorporate strong correlations through a density functional theory closure, while transport enters through a relaxati... | a dynamic density functional theory approach to diffusion in white dwarfs and neutron star envelopes |
in this work, we explore different aspects in which strong magnetic fields play a role in the composition, structure and evolution of neutron stars. more specifically, we discuss (i) how strong magnetic fields change the equation of state of dense matter, alter its composition, and create anisotropies, (ii) how they ch... | many aspects of magnetic fields in neutron stars |
magnetars are neutron stars having extreme magnetic field strengths. study of their emission properties in quiescent state can help understand effects of a strong magnetic field on neutron stars. sgr 0501+4516 is a magnetar that was discovered in 2008 during an outburst, which has recently returned to quiescence. we re... | x-ray observations of magnetar sgr 0501+4516 from outburst to quiescence |
we present x-ray and radio monitoring observations of the gamma-ray binary psr j2032+4127/mt91 213 during its periastron passage in late 2017. dedicated chandra, xmm-newton, nustar x-ray observations, and very large array radio observations of this long orbit (50 yr), 143 ms pulsar/be star system clearly revealed flux ... | x-ray and radio variabilities of psr j2032+4127 near periastron |
we present a new mechanism for deep crustal heating in accreting neutron stars. charged pions (π+) are produced in nuclear collisions on the neutron star surface during active accretion and upon decay they provide a flux of neutrinos into the neutron star crust. for massive and/or compact neutron stars, neutrinos depos... | deep crustal heating by neutrinos from the surface of accreting neutron stars |
we investigate whether the intrinsic spin of neutron stars (nss) leaves an observable imprint on the spectral properties of x-ray binaries. to evaluate this, we consider a sample of nine nss for which the spins have been measured that are not accreting pulsars (for which the accretion geometry will be different). for e... | the impact of neutron star spin on x-ray spectra |
we report on the long-term flux relaxation of the magnetar sgr 1627-41 after its 2008 outburst, and evidence for hard x-ray excess measured with nustar. we use new observations made with chandra and xmm-newton, and an archival nustar observation, which add flux measurements at ∼2000 days into quiescence after the 2008 ... | flux relaxation after two outbursts of the magnetar sgr 1627-41 and possible hard x-ray emission |
we carry out the first robust numerical simulation of accretion flows on a weakly magnetized neutron star using smoothed particle hydrodynamics (sph). we follow the two-component advective flow (tcaf) paradigm for black holes and focus only on the advective component for the case of a neutron star. this low-viscosity s... | timing properties of shocked accretion flows around neutron stars in the presence of cooling |
context. transient neutron star low-mass x-ray binaries undergo episodes of accretion, alternated with quiescent periods. during an accretion outburst, the neutron star heats up due to exothermic accretion-induced processes taking place in the crust. besides the long-known deep crustal heating of nuclear origin, a like... | long-term temperature evolution of neutron stars undergoing episodic accretion outbursts |
we study the cooling of isolated neutron stars with particular regard to the importance of nuclear pairing gaps. a microscopic nuclear equation of state derived in the brueckner-hartree-fock approach is used together with compatible neutron and proton pairing gaps. we then study the effect of modifying the gaps on the ... | nuclear pairing gaps and neutron star cooling |
summaryeffective biosecurity and pest management are fundamental to sustainable development. invasive ants pose significant risks to the environment and economy, which are well‑managed by biosecurity agencies in developed countries. however, a comprehensive view of the potential impacts of invasive ants in developing p... | predicting socio‑economic and biodiversity impacts of invasive species: red imported fire ant in the developing western pacific |
we study the quiescent luminosities of accreting neutron stars by a new mechanism as neutrino heating for additional deep crustal heating, where the neutrino heating is produced by charged pions decay from the nuclear collisions on the surface of neutron star during its active accretion. for low mass neutron star (≲1.4... | quiescent luminosities of transiently accreting neutron stars with neutrino heating due to charged pion decay |
the fundamental difference between accretion around black holes and neutron stars is the inner boundary condition, which affects the behavior of matter very close to the compact objects. this leads to formation of additional shocks and boundary layers for neutron stars. previous studies on the formation of such boundar... | two-component advective flows around neutron stars |
starting from a separable pairing force of finite range of nucleons, a new set of the pairing strengths for the 1s0 hyperon-hyperon pairing based on the quark model is proposed and the 1s0 hyperon superfluidity in neutron stars with the new hyperon pairing strengths is investigated. the reliable λ λ pairing strength is... | 1s0 hyperon superfluidity in neutron stars from a separable pairing force of finite range |
binary neutron star mergers are believed to eject significant masses with a diverse range of velocities. once these ejected materials begin to be decelerated by a homogeneous medium, relativistic electrons are mainly cooled down by synchrotron radiation, generating a multiwavelength long-lived afterglow. analytic and n... | light curves of a shock-breakout material and a relativistic off-axis jet from a binary neutron star system |
we examine the influence of the density dependence of the symmetry energy on several properties of neutron stars. in particular, we study the constraints set on the nuclear matter equation of state by the values of the tidal deformability and neutron star radius, using a diverse set of relativistic and non-relativistic... | neutron star properties: constraining the nuclear matter eos |
we monitored the neutron star low-mass x-ray binary sax j1750.8-2900 after the end of its 2015/2016 outburst using the x-ray telescope (xrt) aboard swift to detect possible post-outburst 'rebrightenings', similar to those seen after its 2008 outburst. we did not detect any rebrightening behaviour, suggesting that the p... | variable quiescent state for the neutron-star x-ray transient sax j1750.8-2900: not such a hot neutron star after all? |
recent long-term radio follow-up observations of gw170817 reveal a simple power-law rising light curve, with a slope of {t}0.78, up to 93 days after the merger. the latest x-ray detection at 109 days is also consistent with such a temporal slope. such a shallow rise behavior requires a mildly relativistic outflow with ... | early soft x-ray to uv emission from double neutron star mergers: implications from the long-term observations of gw170817 |
we have derived analytic expressions that describe cooling of isolated neutron stars with nucleon cores after reaching the state of internal thermal relaxation. the results are valid for a wide class of equations of state of nucleonic matter and, in this sense, are universal. moreover, they accurately reproduce the evo... | analytic description of neutron star cooling |
the light curve of gw170817 is surprisingly blue and bright. assuming that the event is a binary neutron star merger, we argue that blueness and brightness of the light curve is the result of ejecta that contains an substantial amount of thermal energy. to achieve this, the ejecta must be reheated at a substantial dist... | gw170817: a neutron star merger in a mass-transferring triple system |
we report on a detailed study of the spectral and temporal properties of the neutron star low-mass x-ray binary slx 1737-282, which is located only ∼1° away from sgr a*. the system is expected to have a short orbital period, even within the ultracompact regime, given its persistent nature at low x-ray luminosities and ... | the very faint hard state of the persistent neutron star x-ray binary slx 1737-282 near the galactic centre |
this paper consists of two related parts: in the first part we derive an expression of the moment of inertia (moi) of a neutron star as a function of observables from a hypothetical r-mode gravitational-wave detection. for a given r-mode detection we show how the value of the moi of a neutron star constrains the equati... | constraining the r-mode saturation amplitude from a hypothetical detection of r-mode gravitational waves from a newborn neutron star: sensitivity study |
we investigate the impact of pairing correlations on neutrino transport in stellar matter. our analysis is extended to nuclear matter conditions where large density fluctuations may develop, associated with the onset of the liquid-vapor phase transition, and where clustering phenomena occur. within a thermodynamical tr... | pairing effects on neutrino transport in low-density stellar matter |
during very early age of neutron stars, the core cools down faster compared to the crust creating a large thermal gradient in the interior of the star. during 10 - 100 years, a cooling wave propagates from the core to the crust causing the interior of the star to thermalize. during this duration thermal properties of t... | thermal properties of the core of magnetar |
young neutron stars cool via the emission of neutrinos from their core. a precise understanding of all the different processes producing neutrinos in the hot and degenerate matter is essential for assessing the cooling rate of such stars. the main standard model processes contributing to this effect are ν bremsstrahlun... | anomaly induced cooling of neutron stars: a standard model contribution |
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