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Accreting Neutron Stars - Crossref

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Last Updated: 03 November 2022

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GRMHD simulations of accreting neutron stars I: Non-rotating dipoles

ABSTRACT We investigate the general-relativistic behavior of matter being accreted to and ejected by a magnetized and non-rotating neutron star, as well as its non-rotating neutron star. We can determine consistently the position of the magnetospheric radius rmsph and investigate how it changes with the magnetic moment u03bc and the accaccuation rate by making use of a number of simulations in which we change the direction of the stellar dipolar magnetic field. The total torque in solid magnetic field simulations differs dramatically, but the unsteady torques observed in the simulations may be attributed to spin fluctuations observed in X-ray pulsars.

Source link: https://doi.org/10.1093/mnras/stac2510


Magnetically confined mountains on accreting neutron stars with multipole magnetic fields

If the neutron star has strong multipole magnetic fields, the mountain's mass ellipticity rises by an order of magnitude. If the neutron star has a dipole magnetic field, the dipole magnetic field is buried and converted into multipole components. By comparison, if the neutron star has both dipole and high multipole magnetic fields, the multipole magnetic fields are buried and transformed into a negative dipole unit. We also calculate magnetically bound mountains with toroidal magnetic fields, finding that the ellipticity becomes marginally smaller when the mountain has toroidal magnetic fields. If the multipole magnetic fields are buried, they maintain the robust toroidal magnetic field near the stellar surface, and the ratio of the toroidal magnetic field to the poloidal magnetic field is close to 100. The buried multipole magnetic fields provide the hidden magnetic fields that are not visible toroidal magnetic fields.

Source link: https://doi.org/10.1093/mnras/stac2585


Thermal evolution and quiescent emission of transiently accreting neutron stars

We investigate the long-term thermal evolution of neutron stars in soft X-ray transients, taking the deep crustal heating into account consistently with crustal change. We updated a compilation of the observational findings with the theoretical findings in the SXTs, including a comparison of the observational findings with the theoretical findings. The quasi-equilibrium thermal luminosity of a neutron star in an SXT can be much lower at the minimum than in the final state. The theory and observations have left the previous conclusions unchanged, namely that the direct Urca process works in relatively cool neutron stars and that an accrescent heat-blanketing envelope is most likely present in SXTs in quiescence. The results of the comparison of theory and observation indicate that the suppression of the triplet pairing type of nucleon superfluidity in the neutron-star matter is not supported.

Source link: https://doi.org/10.1051/0004-6361/201936003


Radio monitoring of transient Be/X-ray binaries and the inflow–outflow coupling of strongly magnetized accreting neutron stars

ABSTRACT: While classical jet-launching plans predict that such NSs cannot launch jets, recent experiments and models show otherwise. The BeXRB Swift J0243. 6+6124's correlation found previously corresponds to its increasing X-ray luminosity, and it lives in a region of the LX's u2013LR plane. We measure a BeXRB LX (u00b1 0. 06 u00b1 0. 06 u00b1) coupling index, which is close to the indices measured in NS and black hole low-mass X-ray binaries. Our findings are presented in the wider context of X-ray binary radio experiments, concluding that our findings reveal how supergiant X-ray binaries could host a previously unknown additional radio emission device.

Source link: https://doi.org/10.1093/mnras/stac2518


Accreting neutron stars from the nuclear energy-density functional theory

Matter deposited on the surface of a neutron star in a low-mass X-ray binder causes X-ray bursts, whose ashes are buried and further processed, thus altering the composition and the stellar crust's properties. In this second paper in a series, the effect of accretion on the equation of state and the global characteristics of neutron stars is investigated in the context of the nuclear energy-density functional theory. We calculated the mass, radius, moment of inertia, and tidal deformability of accaccered neutron stars using these equations of state, as well as catalyzed neutron stars for which combined equations of state based on the same functionals are available.

Source link: https://doi.org/10.1051/0004-6361/202243715


Crustal heating in accreting neutron stars from the nuclear energy-density functional theory

The X-ray observations of soft X-ray transients in quiescence show the presence of heat sources in the crust of accreted neutron stars. The heating in the crust of accreting neutron stars is investigated using a fully quantum strategy that takes into account nuclear shell effects. For the calculation of state of nonaccident neutron stars, we have used the following algorithms to determine the effect of accretion on the crust's structure. The total heat released in the crust is highly sensitive to the details of the nuclear system, and it is expected to lie in the range from 1. 5 MeV to 1. 7 MeV per accaccted nucleon. The occurrence of nuclear shell closures has influenced the evolution of an accaccted matter element and therefore the location of heat sources.

Source link: https://doi.org/10.1051/0004-6361/201833605


GRMHD simulations of accreting neutron stars with non-dipole fields

These actors are reported to have undergone a lengthy accaccaccation spin-up phase, begging the question of how accretion flows on to actors with complicated magnetic fields would look like. In an accelerated millisecond pulsars, this is the first step toward simulating realistic hotspot shapes in a general relativistic framework to investigate hotspot variability in accreting millisecond pulsars. We find that the exact location and size of the accacction columns resulting in hotspots varies dramatically depending on initial stellar field size and geometry. In virtually every parameter condition regime investigated here, we also find that the best contributions to the stellar torque are made from disc-connected field lines and the pulsar wind, leading to spin-down. The discu2013magnetosphere interaction for dipoles can either increase or reduce jet power relative to the isolated case.

Source link: https://doi.org/10.1093/mnras/stac1817


Accreting neutron stars: heating of the upper layers of the inner crust

The crust is thought to be warmed up by accretion-induced exothermic nuclear reactions in the crust. We present thermodynamically consistent estimates of the energy flux in three zones of the stellar crust: at the outer crust interface, in the upper crust's upper layers, and in the underlying crustal layers. We've found new theoretical lower limits for explosive rp ashes and Q u2273 0. 43 MeV for superburst and Kepler ashes, as shown by our experimental lower limits.

Source link: https://doi.org/10.1093/mnrasl/slac059


A Spectroscopic Angle on Central Engine Size Scales in Accreting Neutron Stars

Abstract: Analyses of absorption from disk winds and atmospheres in accreting compact objects often treat the central emitting regions in these systems as point sources relative to the absorber. In this case, a small part of the absorber's Keplerian motion contributes to the velocity width of absorption lines, resulting in absorption lines' length. We've recently reported that this technique was applied to three ultracompact and short-period neutron star X-ray binaries in which evidence of gravitationally redshifted absorption, owing to an inner-disk atmosphere, has been found. 1 320 km s u22121 on the magnitude of this geometric effect and a central engine of size RCE 60 GM/c 2.

Source link: https://doi.org/10.3847/1538-4357/ac3766


Origin of young accreting neutron stars in high-mass X-ray binaries in supernova remnants

ABSTRACT – Several accreting neutron stars have been identified in X-ray binary systems embedded in supernova remnants. A young NS will not reach the Ejector stage of development after a successful fallback episode with certain realistic assumptions of the initial spin period, stellar wind properties, and magnetic field, leading to a relatively rapid onset of accretion within the lifetime of a supernova remnant. U22731014 G and initial spin period u20130. 2 s accu20130. 2 s accretion rate is sufficient to prevent the Ejector stage from occurring.

Source link: https://doi.org/10.1093/mnras/stac332

* Please keep in mind that all text is summarized by machine, we do not bear any responsibility, and you should always check original source before taking any actions

* Please keep in mind that all text is summarized by machine, we do not bear any responsibility, and you should always check original source before taking any actions