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Accretion disks around neutron stars regularly undergo sudden strong irradiation by Type I X-ray bursts powered by unstable thermonuclear burning on the stellar surface. We investigate the impact on the disk during one of the first X-ray…

Recent observations of X-ray pulsars at low luminosities allow, for the first time, to compare theoretical models for the emission from highly magnetized neutron star atmospheres at low mass accretion rates ($\dot{M} \lesssim 10^{15}$ g…

In this paper, we use analytical methods to study the last stages of the double neutron star (NS) system evolution. Depending on the initial masses of the components, this evolution can occur either in the framework of the merging scenario…

High Energy Astrophysical Phenomena · Physics 2024-02-13 Nikita Kramarev , Andrey Yudin

X-ray bursts are thermonuclear flashes on the surface of accreting neutron stars and reliable burst models are needed to interpret observations in terms of properties of the neutron star and the binary system. We investigate the dependence…

High Energy Astrophysical Phenomena · Physics 2016-10-19 R. H. Cyburt , A. M. Amthor , A. Heger , E. Johnson , L. Keek , Z. Meisel , H. Schatz , K. Smith

Strongly magnetized, accreting neutron stars show periodic and aperiodic variability over a wide range of time scales. By obtaining spectral and timing information on these different time scales, we can have a closer look into the physics…

High Energy Astrophysical Phenomena · Physics 2019-05-15 F. Fuerst , P. Kretschmar , V. Grinberg , K. Pottschmidt , J. Wilms , M. Kuehnel , I. El Mellah , S. Martinez-Nunez

The crust of accreting neutron stars plays a central role in many different observational phenomena. In these stars, heavy elements produced by H-He burning in the rapid proton capture (rp-) process continually freeze to form new crust. In…

High Energy Astrophysical Phenomena · Physics 2018-07-04 M. E. Caplan , Andrew Cumming , D. K. Berry , C. J. Horowitz , R. Mckinven

A quasi-statistical equilibrium model is constructed to simulate the multicomponent composition of the crust of an accreting neutron star. The ashes of rp-process nucleosynthesis are driven by accretion through a series of electron…

Nuclear Theory · Physics 2012-05-17 Andrew W. Steiner

We have investigated the crustal properties of neutron stars without fallback accretion. We have calculated the chemical evolution of the neutron star crust in three different cases (a modified Urca process without the thermal influence of…

Solar and Stellar Astrophysics · Physics 2015-05-13 Kelsey Hoffman , Jeremy Heyl

Type-I X-ray bursts can be used to determine properties of accreting neutron stars via comparisons between model calculations and astronomical observations, exploiting the sensitivity of models to astrophysical conditions. However, the…

High Energy Astrophysical Phenomena · Physics 2019-02-19 Zach Meisel , Grant Merz , Sophia Medvid

Neutron stars in low-mass X-ray binaries are thought to be heated up by accretion-induced exothermic nuclear reactions in the crust. The energy release and the location of the heating sources are important ingredients of the thermal…

High Energy Astrophysical Phenomena · Physics 2023-10-02 Nikolay N. Shchechilin , Mikhail E. Gusakov , Andrey I. Chugunov

I review our understanding of the thermonuclear instabilities on accreting neutron stars that produce Type I X-Ray bursts. I emphasize those observational and theoretical aspects that should interest the broad audience of this meeting. The…

Astrophysics · Physics 2009-10-31 Lars Bildsten

Type I X-ray bursts are thermonuclear explosions on the neutron star (NS) surface caused by mass accretion from a companion star. Observations of X-ray bursts provide valuable information on X-ray binary systems, e.g., binary parameters,…

High Energy Astrophysical Phenomena · Physics 2022-01-06 A. Dohi , N. Nishimura , M. Hashimoto , Y. Matsuo , T. Noda , S. Nagataki

Context. Tighter constraints on metal-poor stars we observe are needed to better understand the chemical processes of the early Universe. Computing a stellar spectrum in 3D allows one to model complex stellar behaviours, which cannot be…

Solar and Stellar Astrophysics · Physics 2017-02-22 A. J. Gallagher , E. Caffau , P. Bonifacio , H. -G. Ludwig , M. Steffen , D. Homeier , B. Plez

Transiently accreting Low Mass X-Ray Binaries have the potential to probe the core composition of their neutron stars via deep crustal heating caused by nuclear reactions. We statistically assess this deep crustal heating scenario, taking…

High Energy Astrophysical Phenomena · Physics 2024-06-14 Kaiser Arf , Kai Schwenzer

Here we present models of hot neutron star (NS) atmospheres consisting of thermonuclear ashes of various chemical compositions. These models are essential for studying thermonuclear flashes in X-ray bursting NSs in which nuclear-burning…

High Energy Astrophysical Phenomena · Physics 2026-05-07 Valery F. Suleimanov , Juri Poutanen , Klaus Werner

The observation of X-rays during quiescence from transiently accreting neutron stars provides unique clues about the nature of dense matter. This, however, requires extensive modeling of the crusts and matching the results to observations.…

High Energy Astrophysical Phenomena · Physics 2023-10-03 R. Jain , E. F. Brown , H. Schatz , A. V. Afanasjev , M. Beard , L. R. Gasques , S. S. Gupta , G. W. Hitt , W. R. Hix , R. Lau , P. Moller , W. J. Ong , M. Wiescher , Y. Xu

In February and March 2024, a series of many Type I X-ray bursts from the accreting neutron star SRGA J144459.2$-$604207, which has been identified by multiple X-ray satellites, with the first reports coming from INTEGRAL and NinjaSat.…

Thermal evolution of neutron stars is known to depend on the properties of superdense matter in neutron star cores. We suggest a statistical analysis of isolated cooling middle-aged neutron stars and old transiently accreting…

Solar and Stellar Astrophysics · Physics 2015-07-16 M. V. Beznogov , D. G. Yakovlev

We model the nuclear evolution of an accreted matter as it sinks toward the stellar center, in order to find its composition and equation of state. To this aim, we developed a simplified reaction network that allows for redistribution of…

High Energy Astrophysical Phenomena · Physics 2023-06-28 Nikolay N. Shchechilin , Mikhail E. Gusakov , Andrey I. Chugunov

The heavy element ashes of rp-process hydrogen and helium burning in accreting neutron stars are compressed to high density where they freeze, forming the outer crust of the star. We calculate the chemical separation on freezing for a…

Solar and Stellar Astrophysics · Physics 2016-06-08 Ryan Mckinven , Andrew Cumming , Zach Medin , Hendrik Schatz