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The discovery of the ultraluminous X-ray pulsar M82 X-2 has stimulated lively discussion on the nature of the accreting neutron star. In most of the previous studies the magnetic field of the neutron star was derived from the observed…

High Energy Astrophysical Phenomena · Physics 2017-04-12 Kun Xu , Xiang-Dong Li

Rigid (Uniform) rotation is usually assumed when investigating the properties of mature neutron stars (NSs). Although it simplifies their description, it is an assumption because we cannot observe the NS's innermost parts. Here, we analyze…

High Energy Astrophysical Phenomena · Physics 2024-10-18 Jonas P. Pereira , Tulio Ottoni , Jaziel G. Coelho , Jorge A. Rueda , Rafael C. R. de Lima

Massive stars lose mass in the form of stellar winds and outbursts. This material accumulates around the star. When the star explodes as a supernova (SN) the resulting shock wave expands within this circumstellar medium. The X-ray emission…

High Energy Astrophysical Phenomena · Physics 2015-05-30 Vikram V. Dwarkadas , Julieta Gruszko

We consider the magnetic and spin evolution of isolated neutron stars assuming that the magnetic field is initially confined to the crust. The evolution of the crustal field is determined by the conductive properties of the crust which, in…

Astrophysics · Physics 2015-06-24 Vadim Urpin , Denis Konenkov

One long standing tension between theory and observations of Type I X-ray burst is the accretion rate at which the burst disappear due to stabilization of the nuclear burning that powers them. This is observed to happen at roughly one third…

High Energy Astrophysical Phenomena · Physics 2024-11-18 Martin Nava-Callejas , Yuri Cavecchi , Dany Page

A newly discovered instability in rotating neutron stars, driven by gravitational radiation reaction acting on the stars' $r$-modes, is shown here to set an upper limit on the spin rate of young neutron stars. We calculate the timescales…

Astrophysics · Physics 2009-10-30 Nils Andersson , Kostas Kokkotas , Bernard F. Schutz

Neutron stars are not observed to spin faster than about half their breakup rate. This limiting rotational frequency may be related to the strength of their crusts. As a star spins up from accretion, centrifugal forces stress the crust. We…

High Energy Astrophysical Phenomena · Physics 2024-12-17 J. A. Morales , C. J. Horowitz

Context. In tight binary star systems, tidal interactions can significantly influence the rotational and orbital evolution of both stars, and therefore their activity evolution. This can have strong effects on the atmospheric evolution of…

Solar and Stellar Astrophysics · Physics 2019-06-12 C. P. Johnstone , E. Pilat-Lohinger , T. Lüftinger , M. Güdel , A. Stökl

In a previous paper [M. E. Gusakov, A. I. Chugunov, and E. M. Kantor, Phys. Rev. Lett. 112, 151101 (2014)], we introduced a new scenario that explains the existence of rapidly rotating warm neutron stars (NSs) observed in low-mass X-ray…

Solar and Stellar Astrophysics · Physics 2015-06-16 Mikhail E. Gusakov , Andrey I. Chugunov , Elena M. Kantor

We present the results of hydrodynamical simulations of nonaxisymmetric gas flow past a gravitating compact object in two dimensions. Calculations were performed with uniform flow as well as with transverse velocity and density gradients.…

Astrophysics · Physics 2009-10-28 J. S. Benensohn , D. Q. Lamb , R. E. Taam

We perform general-relativistic hydrodynamical simulations of dynamical capture binary neutron star mergers, emphasizing the role played by the neutron star spin. Dynamical capture mergers may take place in globular clusters, as well as…

High Energy Astrophysical Phenomena · Physics 2016-01-14 William E. East , Vasileios Paschalidis , Frans Pretorius , Stuart L. Shapiro

Pinning of vortex lines in the inner crust of a spinning neutron star may be the mechanism that enhances the differential rotation of the internal neutron superfluid, making it possible to freeze some amount of angular momentum which…

High Energy Astrophysical Phenomena · Physics 2018-02-07 M. Antonelli , A. Montoli , P. M. Pizzochero

Rotation-powered millisecond radio pulsars have been spun up to their present spin period by a $10^8$ - $10^9$ yr long X-ray-bright phase of accretion of matter and angular momentum in a low-to-intermediate mass binary system. Recently, the…

High Energy Astrophysical Phenomena · Physics 2015-06-19 A. Papitto , D. F. Torres , N. Rea , T. Tauris

The loss of angular momentum due to unstable r-modes in hot young neutron stars has been proposed as a mechanism for achieving the spin rates inferred for young pulsars. One factor that could have a significant effect on the action of the…

Astrophysics · Physics 2009-11-07 Anna. L. Watts , Nils. Andersson

Irradiation of the accretion disc causes reflection signatures in the observed X-ray spectrum, encoding important information about the disc structure and density. A Type I X-ray burst will strongly irradiate the accretion disc and alter…

High Energy Astrophysical Phenomena · Physics 2021-11-03 J. Speicher , D. R. Ballantyne , P. C. Fragile

We present the first set of a new generation of models of massive stars of solar composition extending between 13 and 120 \msun, computed with and without the effects of rotation. We included two instabilities induced by rotation, namely…

Solar and Stellar Astrophysics · Physics 2012-12-13 Alessandro Chieffi , Marco Limongi

We report the detection during the JEM-X/INTEGRAL observations of several X-ray bursters of series of close type I X-ray bursts consisting of two or three events with a recurrence time much shorter than the characteristic (at the observed…

High Energy Astrophysical Phenomena · Physics 2017-08-24 S. A. Grebenev , I. V. Chelovekov

Neutron star (NS) masses and radii can be estimated from observations of photospheric radius-expansion X-ray bursts, provided the chemical composition of the photosphere, the spectral colour-correction factors in the observed luminosity…

Precision measurements of neutron star radii can provide a powerful probe of the properties of cold matter beyond nuclear density. Beginning in the late 1970s it was proposed that the radius could be obtained from the apparent or inferred…

High Energy Astrophysical Phenomena · Physics 2015-05-14 Sudip Bhattacharyya , M. Coleman Miller , Duncan K. Galloway

Type I X-ray bursts from low-mass X-ray binaries result from a thermonuclear runaway in the material accreted onto the neutron star. Although typical recurrence times are a few hours, consistent with theoretical ignition model predictions,…

High Energy Astrophysical Phenomena · Physics 2015-05-19 L. Keek , D. K. Galloway , J. J. M. in 't Zand , A. Heger