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we derive an analytic approximation for the emissivity of neutrino-pair bremsstrahlung (npb) due to scattering of electrons by atomic nuclei in a neutron star (ns) crust of any realistic composition. the emissivity is expressed through generalized coulomb logarithm by introducing an effective potential of electron-nucl... | an effective potential for electron-nucleus scattering in neutrino-pair bremsstrahlung in neutron star crust |
thorne-żytkow objects (tżos) are a theoretical class of star in which a compact neutron star is surrounded by a large, diffuse envelope. supergiant tżos are predicted to be almost identical in appearance to red supergiants (rsgs), with their very red colors and cool temperatures placing them at the hayashi limit on the... | discovery of a thorne-żytkow object candidate in the small magellanic cloud |
we propose to continue our very successful program to use the observed cooling of the crusts in transiently accreting neutron star x-ray binaries to probe the behavior of ultra-dense matter. those crusts are heated due to the accretion of matter during the outbursts of those transients. after the outbursts are over the... | crust cooling of accretion-heated neutron stars |
black hole-accretion disk systems from compact binary mergers are possible engines for short duration gamma-ray bursts (grbs). in this scenario the evolution of the post-merger remnant torus is determined by a combination of neutrino cooling and magnetically-driven heating processes. we study the post-merger evolution ... | evolution of the magnetized, neutrino-cooled accretion disk in the aftermath of a black hole neutron star binary merger |
we propose a 45-ks chandra observation to continue our monitoring of the quiescent neutron star x-ray binary exo 0748-676. a 25-year long accretion outburst severely heated the neutron star crust, which has been gradually cooling since the source returned to quiescence in 2008. monitoring this thermal evolution provide... | the x-ray and uv spectra of the quiescent neutron star x-ray binary exo 0748-676 |
we study the v\bar v-pair emission from electrons and protons in a relativistic quantum approach. in this work we calculate the luminosity of the v\bar v-pairs emitted from neutron-star-matter with a strong magnetic field, and find that this luminosity is much larger than that in the modified urca process. the v\bar v-... | neutrino and antineutrino pair-emission in strong magnetic field in relativistic quantum approach |
near infrared (nir) flare/rebrightening in the afterglow of the short hard gamma ray burst (shb) 130603b measured with the hubble space telescope (hst) and an alleged late-time x-ray excess were interpreted as possible evidence of a neutron-star merger origin of this shb. however, the x-ray afterglow that was measured ... | grb 130603b: no compelling evidence for neutron star merger |
based on the special relativistic hydrodynamic equations and updated cooling function, we investigate the long-term evolution of neutron stars merger (nsm) remnants by a one-dimensional hydrodynamic code. three nsm models from one soft equation of state, sfho, and two stiff equations of state, dd2 and tm1, are used to ... | hydrodynamic evolution of neutron star merger remnants |
superfluidity in the crust is a key ingredient for the cooling properties of proto-neutron stars. present theoretical calculations employ the quasi-particle mean-field hartree-fock-bogoliubov theory with temperature dependent occupation numbers for the quasi-particle states. finite temperature stellar matter is charact... | the heat capacity of the neutron star inner crust within an extended nse model |
the observation of thermal emission from isolated neutron stars and the modeling of the corresponding cooling curves has been very useful to get information on the properties of matter at very high densities. more recently, the detection of quiescent thermal emission from neutron stars in low mass x-ray binary systems ... | inferring neutron stars crust properties from quiescent thermal emission |
both the symmetry energy part and excluded volume corrections to the equation of state play an important role for the neutron star interior structure and composition, namely for the profile of the baryon density and the proton fraction. while the symmetry energy uniquely determines the proton fraction, excluded volume ... | interplay between symmetry energy and excluded volume corrections under the direct urca cooling constraint in neutron stars |
neutron star mergers provide us with a remarkable laboratory to test the laws of physics in dense environments, to constrain the production sites of heavy elements, and to understand high-energy transients like gamma-ray bursts. neutrinos play an important role in these mergers: they are the main source of cooling in p... | monte-carlo radiation transport in neutron star merger simulations |
the 1 km thick crust of neutron stars is strongly heated by nuclear reactions during accretion outbursts, but cools in quiescence. hete j1900.1-2455 continously accreted since 2005, but in 2015 late oct its intensity dropped below the detection limit of maxi. swift observations (mar 7) fail to detect the source, implyi... | an exceptionally cold neutron star in hete j1900.1-2455 |
strongly interacting fermions define the properties of complex matter throughout nature, from atomic nuclei and modern solid state materials to neutron stars. ultracold atomic fermi gases have emerged as a pristine platform for the study of many-fermion systems. in this poster we demonstrate the realization of a quantu... | quantum gas microscope for fermionic atoms |
we used high-resolution spectra of all bright (v<8mag) f5 and cooler stars (teff<6500k) in several selected sky fields near the north ecliptic pole including tess northern continuous viewing zone (cvz). we used the 1.65m telescope at the moletai astronomical observatory of vilnius university in lithuania that is ... | vizier online data catalog: abundances of neutron-capture elements (tautvaisiene+, 2021) |
we are developing a concept for a new canadian-led x-ray observatory — colibrì. the main objectives of the colibrì mission are to study the structure of accretion flows in the near vicinity of black holes and neutron stars, the emission from the surfaces of neutron stars, and the intergalactic medium. the colibrì conce... | the colibri x-ray telescope |
the cooling behavior of neutron stars (nss) is a key observational test of the physics of their interiors, which can be probed through x-ray observations. while nss are hot enough to be studied in the x-ray, their long-term cooling is dominated by neutrino emission from the core. this enables us to constrain the neutri... | neutron star cooling |
previous studies of the young (340 yr) central compact object (cco) in the cas a supernova remnant resulted in a reported decrease of the cco's surface temperature by about 2% in 10 years. however, the actual rate of this exceptional cooling is still uncertain as the most recent data hint at a puzzling difference betwe... | monitoring the thermal evolution of the cas a cco |
we propose to continue our very successful program to use the observed cooling of the crusts in transiently accreting neutron star x-ray binaries to probe the behavior of ultra-dense matter. those crusts are heated due to the accretion of matter during the outbursts of those transients. after the outbursts are over the... | crust cooling of accretion-heated neutron stars |
a neutron star is a highly dense object which lasts after a supernova explosion. the density of a neutron star overcomes the nuclear density, and the temperature is high at the beginning of its history. an isolated neutron star does not have any heat sources, and it cools down emitting thermal energy by neutrinos. the ... | neutron star cooling with various superfluid and superconducting states |
we propose a 135 ks chandra observation of the globular cluster terzan 5, to continue our study of the thermal evolution of the transiently accreting neutron star igr j17480-2446. our previous chandra observations revealed that the crust of this neutron star was strongly heated during a 10-week long accretion outburst ... | probing the physics of neutron stars using terzan 5 |
we analyze the effects of pairing correlations on the behavior of stellar matter, focusing on thermodynamical conditions close to the onset of the liquid-gas phase transition, which are characterized by quite large density fluctuations and where clustering phenomena occur. we concentrate on the neutrino transport prope... | impact of pairing on clustering and neutrino transport properties in low-density stellar matter |
we propose to study the cooling of the neutron star crust in maxi j0556-332 after its most recent (fourth) outburst. of all cooling neutron stars in lmxbs, maxi j0556-332 has shown by far the strongest shallow heating. this is a process of unknown origin in the upper layers of the neutron star crust that dominates the ... | shallow heating in the neutron star crust of maxi j0556?-332 |
the central compact object (cco) in the cas a snr is a 340 yrs old neutron star. a decrease of its surface temperature by at least 2% in 10 years has been reported, on an 18 years baseline. the used acis data were affected by time-dependent instrumental effects (particularly pileup). the unknown time-dependent systemat... | monitoring the thermal evolution of the cas a cco |
weak decay processes (like direct and modified urca) play an important role in transport phenomena in neutron stars and neutron star mergers. the traditional treatment for the in-medium nucleon propagator in the modified urca process uses crude approximations. we are developing an approach to unify direct and modified ... | a unified approach to urca processes |
what is the heaviest element that can, if it is very short lived, exist in nature? this simple, yet profound question has urged us to synthesize unknown superheavy nuclei (shn) at terrestrial accelerator facilities all over the world. the synthesis of shn is notoriously difficult due to its really tiny cross sections o... | a new perspective of the study of superheavy nuclei |
this study presents multiphysics analyses of the electron target cooling system of the accelerator-driven system (ads) of the kharkiv institute of physics and technology (kipt) using mcnp and fluent computer programs. mcnp has been used to transport electrons, gammas, and neutrons, and to calculate the energy depositio... | electron target cooling analyses of the kipt ads using mcnp and ansys fluent |
this paper presents the theory and application of a code called callisto which is used for performing npp start-up and power ascension calculations. the callisto code is designed to calculate various values relating to the neutron population of a nuclear system which contains a low number of neutrons. these variables i... | callisto-spk: a stochastic point kinetics code for performing low source nuclear power plant start-up and power ascension calculations |
unlike the commonly known rotation-powered pulsars, x-ray thermal isolated neutron stars (xtinss) do not show radio/gamma-ray emission or other signs of magnetospheric activity but emit purely thermal soft x-ray radiation. a few hst observations of these sources have shown very puzzling results, with possible contribut... | the most puzzling uv-optical-nir spectrum of an isolated neutron star: a disk or a magnetosphere? |
we discuss the effect of the chemical composition of heat blanketing envelopes of neutron stars (nss) on the interpretation of the observations of these stars. first we analyze the diffusive fluxes of ions in non-isothermal and non-ideal coulomb plasmas. then we outline models of diffusively-equilibrated heat blanketin... | heat blanketing envelopes vs cooling of neutron stars |
neutron stars are high-density objects formed by the gravitational collapse of massive stars, and the whole star can be likened to a giant nucleus. the interior of a neutron star is considered to contain exotic particles and states which do not appear in a normal nucleus. the internal states are constrained by observat... | cooling of neutron stars with quark-hadron continuity |
the direct urca process of rapid neutrino emission can occur in nonuniform nuclear pasta phases that are expected in the inner crust of neutron stars. here, the periodic potential for a nucleon in nuclear pasta allows momentum conservation to be satisfied for direct urca reactions. we improve on earlier work by modelin... | fast neutrino cooling of nuclear pasta in neutron stars: molecular dynamics simulations |
as an advanced research tool, neutronics and thermal-hydraulics coupling have a wide range of promising applications in the field of nuclear energy. this paper develops a burnup-control drum coupling code based on the monte carlo code rmc and the computational fluid dynamics (cfd) program star-ccm +. the dynamic adjust... | burnup-control drum coupling characteristics investigation of lead-bismuth eutectic-cooled solid reactor |
neutron-rich matter exists naturally in neutron stars and some nuclei. it can also be created during mergers of neutron stars in space and collisions between two heavy nuclei in terrestrial nuclear laboratories. the nature and equation of state (eos) of such matter are still very poorly known while they have broad impa... | probing symmetry energy of dense neutron-rich matter |
neutron stars are heated during accretion episodes due to nuclear reactions that occur in their crust, while they cool primarily through neutrino emissions from their core. during quiescence, the thermal glow of a neutron star can be detected with sensitive x-ray satellites. comparing the observed thermal quiescent x-r... | an unexplored regime of neutron star heating and cooling |
compact binary mergers involving at least one neutron star are promising sites for the synthesis of r-process elements found in stars and planets. however, mergers can take place at significant offsets from their host galaxies, with many occurring several kpc from star-forming regions. it is thus important to understan... | r-process rain from binary neutron star mergers in the galactic halo |
a method of uncertainty quantification in the calculation of wait-time probability distributions in delayed supercritical systems is presented. the method is based on monte carlo uncertainty quantification and makes use of the computationally efficient gamma distribution method for prediction of the wait-time probabili... | importance of parametric uncertainty in predicting probability distributions for burst wait-times in fissile systems |
we present results from fully relativistic simulations of binary neutron star mergers varying the tabular equation of state used to approximate the degenerate material and the mass ratio. the simulations incorporate both magnetic fields and the effects of neutrino cooling. in particular, we examine the amount and prope... | mergers of binary neutron star systems |
recently, it has been discovered that the beta+decay rates and neutrino loss rates of 64ga and 68se greatly affect the light curves and final abundances of x-ray bursts in a one-zone model in all circumstances. here we further expand the study to the multizone model mesa and compare the results with observations of the... | sensitivity studies on the thermal beta+decay and thermal neutrino loss rates in the multizone x-ray burst model mesa |
the equation of state (eos) for nuclear matter at finite temperature and out of equilibrium is a fundamental ingredient for simulations of binary neutron star mergers, calculation of cooling curves, and other transport properties. we construct four new eoss using a relativistic mean-field theory (rmf). typically, the c... | equations of state at finite temperature and out of equilibrium calibrated using chiral effective field theory |
this paper describes a novel methodology for the analysis of nuclear criticality excursions in fissile powder beds under wetting conditions. these potentially hazardous powder, slurry and sludge systems may be found in nuclear fuel manufacturing and fabrication facilities. a point neutron kinetics model was coupled wit... | mathematical and computational models for simulating transient nuclear criticality excursions within wetted fissile powder systems |
this paper describes a probabilistic method of modelling point nuclear systems with low numbers of neutrons including the effects of delayed neutron precursors and its coupling with standard point kinetics equations. this coupling allows the simulation of the non-deterministic progression of a system transitioning from... | coupled probabilistic and point kinetics modelling of fast pulses in nuclear systems |
we propose to observe the tev-emitting supernova remnanthess j1731347for 36 ks to measureits expansion rate by comparing the new image of the x-ray filaments with that obtained in 2008. we willalso search for variability within filaments, and measure the displacement between the remnants centralneutron star and its for... | constraining the expansion rate of the supernova remnant hess j1731-347 |
the doppler beaming effect for cool stars is amplified relative to a blackbody of the same temperature because of deep tio and vo absorption features. also, a strong na feature at 5890a coincides with the short wavelength cutoff of the tess response function. we simulated doppler beaming for bt-settl model spectra rang... | a source of uncertainty in tess photometry of high-velocity m dwarfs |
recent detections of high mass gravitational wave events in the upper neutron star mass range have raised the question, if near equal mass black hole -neutron star (bhns) systems could form and merge, and how they would be distinct from a binary neutron star merger. in this talk, i will present general-relativistic mag... | near equal mass black hole - neutron star mergers: general-relativistic magnetohydrodynamics simulations with realistic microphysics |
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 |
neutrinos act as an important cooling mechanism in an array of explosive astrophysical events. modeling of their fluxes and spectra is key for the interpretation of their detection and the understanding of the synthesis of heavy elements. the neutrino surface is key in the modeling of neutrino spectra. in previous work... | nucleon-nucleon interaction and the neutrino surface of neutron star mergers |
type i x-ray bursts are unstable nuclear burning processes that occur on the surface of neutron star in low-mass x-ray binary. the radiation of type i x-ray bursts can have significant effects on matter around neutron stars. we review the observations and theoretical interpretations of the interaction between type i x-... | the research progress of the interaction between type i x-ray burst and matter around neutron stars |
the goal of this study is to improve a micro reactor core into uniform power distribution, a smaller and safer core. neutronic thermal-hydraulics coupling is an effective means to study the characteristics of microreactors. this paper performs an improvement work of lead-bismuth eutectic alloy (lbe) cooled solid core u... | improved design of lbe cooled solid reactor using 3d neutronics thermal-hydraulics coupling method |
neutron stars and magnetars possess extremely strong magnetic fields. radiative cooling of plasma particles in their magnetospheres can be short compared to the plasma dynamical time. such magnetospheres are observed to produce strong flares, which indicates production of a relativistic pair plasma. how does the partic... | on motion of an charge in a magnetar magnetosphere |
the charge radius of 54ni was determined for the first time using collinear laser spectroscopy at the beam cooling and laser spectroscopy (becola) facility. combined with the known charge radius of its mirror partner 54fe, the slope l of symmetry energy in the nuclear equation of state was determined. the details of th... | charge radius of neutron deficient 54ni and symmetry energy constraints using the difference in mirror pair charge radii |
some astronomical mysteries are found deep in the interiors of stars. such is the case with the puzzle of q-branch white dwarfs, a population of these evolved, dense stars that seems to have an unexpected heat source, causing them to cool more slowly than a typical white dwarf. one hypothesis proposes that q-branch whi... | featured image: to heat a white dwarf |
we examine the frequencies of the gravitational waves radiating from the protoneutron star produced via the core‑collapse supernova. in a way similar to the cold neutron star, we find that the frequencies of the w1 and f mode gravitational waves can be, respectively, expressed well as a function of the stellar compactn... | gravitational waves from protoneutron stars and nuclear equation of state |
dense matter in neutron star crusts can be studied in transient low-mass x-ray binaries. in these systems, the accretion during outbursts compresses the underlying layers, heating the crust out of equilibrium with core. once the system is in quiescence, monitoring the thermal evolution of the crust allows us to probe d... | investigating late-time evolution of exo 0748-676 |
super asymptotic giant branch (super-agb) stars reside in the mass range ~ 6.5-10 m⊙ and bridge the divide between low/intermediate-mass and massive stars. they are characterised by off-centre carbon ignition prior to a thermally pulsing phase which can consist of many tens to even thousands of thermal pulses. with the... | hiding in plain sight - red supergiant imposters? super-agb stars |
we present the results of chandra observations of two non-accreting millisecond pulsars psrs j1640+2224 (j1640) and j1709+2313(j1709), with low inferred magnetic fields in order to constrain their surface temperatures, obtain limits on the amplitude of unstable r-modes in them and make comparisons with similar limits o... | where are the r-modes? chandra observations of millisecond pulsars |
neutron stars and magnetars possess extremely strong magnetic fields, so that radiative cooling of particles in their magnetospheres can be short compared to a plasma dynamical time. the magnetospheres are observed to produce strong flares, possibly due to reconnection, which is a source of high-energy particles. how d... | on trapped particle motion in a strong magnetic field |
binary neutron star mergers can drive dynamical outflows of neutron rich material. these ejecta might be the astrophysical site of production of the r-process elements. in this talk, i will present very recent full-gr, numerical relativity, simulations of binary neutron star mergers with microphysical equation of state... | dynamical ejecta from binary neutron star mergers |
hyperaccreting disks around black holes are the engines that drive outflows and jets in gamma ray bursts (grbs). the torus formed after the core collapse or a compact binary merger is composed of free nucleons, helium, electron-positron pairs, and is cooled by neutrinos rather than photon emission. hyperaccretion power... | on the gamma-ray burst - gravitational wave association in gw150914 |
in this work, we present a calculation of the non-fermi liquid correction to the specific heat of magnetized degenerate quark matter present at the core of the neutron star. the role of non-fermi liquid corrections to the neutrino emissivity has been calculated beyond leading order. we extend our result to the evaluati... | role of magnetic interactions in neutron stars |
both hot and cool evolved stars, e.g., red (super)giants and wolf-rayet stars, lose copious amounts of mass, momentum and mechanical energy through powerful, dense stellar winds. the interaction of these outflows with their surroundings results in highly structured and complex circumstellar environments, often featurin... | shaping the outflows of evolved stars |
the thermal evolution of neutron stars is a subject of intense research, both theoretical and observational. the evolution depends very sensitively on the state of dense matter at supranuclear densities, which essentially controls the neutrino emission. the evolution depends, too, on the structure of the stellar outer ... | thermal evolution of neutron stars |
we calculate the neutrino mean free path in cold neutron matter with some modern brussels-montreal functionals. the three typical functionals used in this article produce quite different results implying a possible impact on the cooling mechanism of neutron stars. | neutrino mean free path in neutron matter with brussels-montreal skyrme functionals |
we study the dynamical evolution of the gravitational-wave driven instability of the f-mode in rapidly rotating relativistic stars. with an approach based on linear perturbation theory we describe the evolution of the mode amplitude and follow the trajectory of a newborn neutron star through its instability window. we ... | the f-mode instability in relativistic neutron stars |
accretion flow around a black hole or a neutron star emits high energy radiations with varying spectral and temporal properties. observed temporal variations point to the existence of a mechanism, dictated by the flow dynamics and not by the stellar surface or magnetic fields, that is common in both types of compact ob... | what is the origin of qpos in accreting neutron stars? |
a model and algorithm for the cooling of the magnetized neutron stars are presented. the cooling evolution described by a system of parabolic partial differential equations with non-linear coeffcients is solved using the alternating direction implicit method. a difference scheme and the preliminary results of simulatio... | an algorithm for the simulation of the magnetized neutron star cooling |
possible mechanisms of creation of both hyperheavy nuclei by electron-nuclear collapse and neutron matter by condensation of ultracold neutrons are discussed. the fundamental possibility of the existence of such objects was previously substantiated by a.b.migdal, who suggested that the known set of proton-neutron nucle... | obtaining neurton matter and hyperheavy nuclei: possible quantum-technological instrumental approaches |
the historical gravitational wave detections of last years ushered in a new era for the study of massive binaries evolution. in high mass x-ray binaries, a transient albeit decisive phase preceding compact binaries, a compact accretor orbits a massive star and captures part of its intense stellar wind. from the stellar... | enhanced accretion and wind-captured discs in high mass x-ray binaries |
through the relativistic mean field theory and relevant weakinteractional cooling theories, the relativistic cooling properties inconventional and hyperonic neutron star matter are studied. also a comparison betweenrelativistic and non-relativistic results with the consideration of the gravity correction is performed.r... | relativistic correction on neutrino emission from neutron stars |
considering the octet baryons in relativistic mean field (rmf) theory, the entropy per baryon is selected to be 1 or 2. we investigate the influence of the entropy per baryon for the massive protoneutron star corresponding to psr j0348+0432. one set of coupling constants gl85 in rmf are selected to reproduce the mass o... | composition and structure of massive protoneutron star psr j0348+0432 |
one of the key aspects in the comprehension of neutron star (ns) interiors is the identification of observables that may impose constraints on the equation of state (eos). at present, limits are obtained mainly through the study of the mass-radius relationship, the maximum rotational frequency and the cooling behaviour... | toward linking fluid pulsation modes to the internal composition of neutron stars |
neutron stars in low mass x-ray binaries accrete enough mass over their lifetimes to replace their entire crust. the accreted matter undergoes a series of nuclear reactions in the crust as it is compressed by continued accretion to higher density. these reactions, which include electron captures, neutron emissions, and... | heating and cooling in accreting neutron stars |
precise measurement of the mass-radius relation of a neutron star (ns) is crucial to determine the equation of state of the ultra dense matter. instead of directly measuring the mass and radius, it is often measured the mass-radius ratio, i.e. gravitational redshift at the ns surface, as it is free from the uncertainty... | a broad spectral feature detected during the cooling phase of a thermonuclear x-ray burst from grs 1747-312 with suzaku |
studying thermal evolution of neutron stars (nss) is one of a few ways to investigate the properties of superdense matter in their cores. we study the cooling of isolated nss (inss) and deep crustal heating of transiently accreting nss in x-ray transients (xrts, binary systems with low-mass companions). currently, near... | statistical approach to thermal evolution of neutron stars |
in this work, we investigate the properties of hybrid stars based on the togashi eos with a low value for the symmetry energy. we adopt the togashi eos and (2 + 1) - flavor njl eos to describe the hadron matter and quark matter, respectively, and construct the hybrid star with the 3-window interpolation approach. the s... | the properties of hybrid stars in a low symmetry energy model |
in this talk, i will present our recent work on a new mechanism for deep crustal heating in accreting neutron stars. during active accretion, charged pions (π+) are produced in nuclear collisions on the neutron star surface. upon decay, they provide a flux of neutrinos into the neutron star crust. we find that for mass... | deep crustal heating and neutron star cooling observation |
pulsars are stars from which electromagnetic radiation is observed to pulsate in well-defined time intervals as the star rotates and the emission of eletromagnetic signal is located in a place different from the rotation center. the frequencies of the pulses decay with time, quantified by the braking index (n). in the ... | the influence of superfluid core cooling in the braking index of pulsars. |
<strong>symbiotic stars are interacting binaries</strong> consisting of an evolved, <strong>cool giant</strong> that is transferring mass to a hot companion - a <strong>white dwarf</strong> or rarely a neutron star. the presence of both ionized and neutral regions in their surroundin... | characterizing cool giants in symbiotic binaries using the gaia edr3 data |
type i x-ray bursts are thermonuclear flashes observed from the surfaces of accreting neutron stars in low mass x-ray binaries. oscillations have been observed during the rise and/or decay of some of these x-ray bursts. those seen during the rise can be well explained by a spreading hot spot model, but large amplitude ... | burst oscillation studies with nicer |
we propose the first observational study of the thermal evolution of old neutron stars (nss) through far-uv observations of three nearby pulsars in the age range from 17 myr to 6 gyr. the cooling history of younger nss is being mapped out in the x-rays, providing important information on the properties of the super-den... | thermal evolution of old neutron stars |
binary star systems composed of two white dwarfs are a natural outcome of stellar evolution. angular momentum losses from gravitational wave radiation cause the binary system's orbit to shrink until the two white dwarfs merge. the final outcome of the merger depends on the masses of the white dwarfs. some potential out... | the long-term outcomes of double white dwarf mergers |
the possible presence of amorphous and heterogeneous phases in the inner crust of a neutron star is expected to reduce the electrical conductivity of the crust, with potentially important consequences on the magneto-thermal evolution of the star. in cooling simulations, the disorder is quantified by an impurity paramet... | inner crust of a neutron star at the point of crystallization in a multicomponent approach (corrigendum) |
in neutron stars the nuclear asymmetric matter is expected to undergo phase transitions to a superfluid state. according to simple estimates, neutron matter in the inner crust and just below should be in the s-wave superfluid phase, corresponding to the neutron-neutron 1s0 channel. at higher density in the core also th... | superfluid phonons in neutron star core |
low mass x-ray binaries are star systems in which a neutron star or a small black hole is paired with a companion star with mass comparable to that of the sun. during accretion, the companion star donates matter to the compact object in the system and increases its temperature. when accretion ends, a stage called quies... | digging deeper into the properties of a cooling neutron star's crust |
neutron stars are unique natural laboratories to study bulk nuclear matter. our understanding of these dense stars has been driven by x-ray and gamma-ray observatories; by the detection of gravitational waves; and by ground-breaking nuclear physics experiments and the coming facility for rare isotope beams. for low-mas... | the complex geology of a neutron star's crust |
we propose a 72 ks epic observation of the recently identified youngpulsar psr j0837-2454. the resulting first-time x-ray spectrum and deepimage of the pulsar, complemented by proposed radio observations, willdetermine whether this pulsar is the first known product of a runawayo/b progenitor star or is a massive neutro... | x-ray properties of the unique runaway or very cool neutron star psr j0837-2454 |
the origin of half of the elements heavier than iron- the so-called r-process elements including gold and uranium, is a central unsolved mystery in astrophysics. recent observations utilising light and gravitational waves have demonstrated that at least some of these elements are formed through the merger of two neutro... | do collapsars create the heaviest elements? |
following a neutron star merger, neutrinos are the primary means of cooling the resulting accretion disk and remnant compact object, they drive outflows, and they determine the abundances of elements formed in the ejecta. state-of-the-art numerical relativity simulations of these mergers employ a variety of methods for... | neutrino kinetics in neutron star mergers |
observations of quasi-persistent x-ray transients yield valuable constraints for neutron star physics and structure. the nuclear reactions which occur during the outburst phase determine the composition of the neutron star crust. during the cooling phase, observations probe the thermal structure of the curst. nuclear r... | production and impact of urca nuclides |
we propose a chandra+swift too program to observe cooling of the neutron star crust in a transiently accreting system, with the aim of probing the behavior and properties of ultra-dense matter. after the crust is heated during an outburst by a variety of nuclear reactions, it will cool down in quiescence until thermal ... | crustal cooling in accretion-heated neutron stars |
passively cooling neutron stars are expected to reach undetectably low surface temperatures $t_s < 10^{4}$ k within less than $10^7$ yr. however, likely thermal ultraviolet emission was detected from the gyr-old millisecond pulsars psr j0437$-$4715 and psr j2124$-$3358 and the $\sim$ $10^7$ yr-old classical pulsar b... | contrasting neutron star heating mechanisms with hubble space telescope observations |
the aim of this slow too proposal is to monitor the next be/x-ray transient and increasing the number of high-magnetic field nss in the small sample to obtain high-quality post-outburst spectra, which hold the key to understanding the physical differences in cooling among nss. for this, the high signal-to-noise and rem... | cooling emission from highly magnetized neutron-star crusts |
risk assessments are fundamental to invasive species management and are underpinned by comprehensive characterization of invasive species impacts. our understanding of the impacts of invasive species is growing constantly, and several recently developed frameworks offer the opportunity to systematically categorize envi... | a global review of socioeconomic and environmental impacts of ants reveals new insights for risk assessment |
we present simulations of the merger of binary neutron star systems calculated with full general relativity and incorporating the global magnetic field structure for the stars evolved with resistive magnetohydrodynamics. our simulation tools have recently been improved to incorporate the effects of neutrino cooling and... | coalescence of magnetized binary neutron star systems |
we analyze broadband x-ray data of ngc 6946 x-1 and probe plausible accretion scenarios in this ulx. ngc 6946 x-1 is a persistent soft source with broadband continuum spectra described by two thermal disk components. the cool accretion disk temperature t cool ~ 0.2 kev and the presence of a ~0.9 kev emission/absorption... | constraint on the accretion of ngc 6946 x-1 using broadband x-ray data |
colibrì is canada's flagship x-ray observatory, proposed to have multiple aperture x-ray optics with cryogenically cooled transition-edge detectors for achieving high-energy and high-time resolution, as well as high throughput and sensitivity in the 0.1-15 kev range. these specifications are tuned to capture the evolvi... | black hole astrophysics with colibrì |
neutron star provides unique environments for the investigation of the physics of extreme dense matter beyond normal nuclear saturation density. in such high density environments, hadrons with strange quarks are expected to play very important role in stabilizing the system. kaons and hyperons are the lowest mass state... | role of strangeness to the neutron star mass and cooling |
crustal cooling of accretion-heated neutron stars provides insight into the stellar interior of neutron stars. the neutron star x-ray transient, ks 1731-260, was in outburst for 12.5 years before returning to quiescence in 2001. we have monitored the cooling of this source since then through chandra and xmm-newton obse... | the thermal state of ks 1731-260 after 14.5 years in quiescence |
the objective of this proposal is to pioneer a new computational tool, the lattice boltzmann method, for simulating condensed nuclear matter in the neutron star inner crust. this will be used to study the properties of the nuclear "pasta" phases, predicted to exist at the crust-core interface, over significantly larger... | lattice boltzmann simulations of soft nuclear astromaterials in neutron star crusts |
a quantitative analysis of luminosity and temperature observations from isolated neutron stars constrains two nucleon superfluid critical temperatures: the neutron triplet superfluid critical temperature and the proton singlet superconducting critical temperature. the neutron star observations imply that the most likel... | constraining superfluidity in dense matter from the cooling of isolated neutron stars |
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