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The X-ray properties of Be/X-ray pulsars in quiescence
Monthly Notices of the Royal Astronomical Society. 2017. Vol. 470. No. 1. P. 126–141.
Wijnands R., Tsygankov S., Degenaar N., Lutovinov A., Poutanen J.
Observations of accreting neutron stars (NSs) with strong magnetic fields can be used not only for studying the accretion flow interaction with the NS magnetospheres, but also for understanding the physical processes inside NSs and for estimating their fundamental parameters. Of particular interest are (I) the interaction of a rotating NS (magnetosphere) with the infalling matter at different accretion rates, and (II) the theory of deep crustal heating and the influence of a strong magnetic field on this process. Here, we present results of the first systematic investigation of 16 X-ray pulsars with Be optical companions during their quiescent states, based on data from the Chandra, XMM-Newton and Swift observatories. The whole sample of sources can be roughly divided into two distinct groups: (I) relatively bright objects with a luminosity around ˜1034 erg s-1 and (hard) power-law spectra, and (II) fainter ones showing thermal spectra. X-ray pulsations were detected from five objects in group (I) with quite a large pulse fraction of 50-70 per cent. The obtained results are discussed within the framework of the models describing the interaction of the infalling matter with the NS magnetic field and those describing heating and cooling in accreting NSs.
V. E. Shaposhnikov, Simonova T. V., Geomagnetism and Aeronomy 2024 Vol. 64 No. 7 P. 1044–1048
The electron cyclotron waves instability near the frequencies of electron cyclotron harmonics in an
electron–positron plasma is studied under conditions typical for the radio emission source with a quasi-harmonic
structure of the pulsar in the Crab Nebula. The increment of instability of longitudinal cyclotron waves
is calculated for an electron–positron plasma with a small admixture of energetic electrons ...
Added: March 11, 2025
Shtykovsky A. E., Lutovinov A., Кривонос Р. А. et al., Письма в Астрономический журнал 2023 Т. 49 № 5 С. 335–344
We present the first results of the SRG observation of the pulsar 4U 1538–52 based on ARC-XC and eROSITA data. An extended emission in the form of a halo is detected around the source in the 0.5–8 keV energy band. Our simulation has shown that its surface brightness distribution can be described by a two-component ...
Added: February 1, 2024
Biryukov A., Beskin G., Monthly Notices of the Royal Astronomical Society 2023 Vol. 522 No. 4 P. 6258–6263
Numerical simulations predict that the spin-down rate of a single rotation-powered neutron star depends on the angle α between its spin and magnetic axes as $P\dot{P} \propto \mu ^2 (k_0 + k_1\sin ^2\alpha)$, where P is the star spin period, μ is its magnetic moment, while k0 ~ k1 ~ 1. Here, we describe a simple observational ...
Added: June 8, 2023
Novoselov E. M., Beskin V. S., Galishnikova A. K. et al., Monthly Notices of the Royal Astronomical Society 2020 Vol. 494 No. 3 P. 3899–3911
At present, there is no direct information about evolution of inclination angle χ between magnetic and rotational axes in radio pulsars. As to theoretical models of pulsar evolution, they predict both the alignment, I.e. evolution of inclination angle χ to 0°, and its counter-alignment, I.e. evolution to 90°. In this paper, we demonstrate that the ...
Added: October 31, 2022
Abolmasov P., Biryukov A., Monthly Notices of the Royal Astronomical Society 2020 Vol. 496 No. 1 P. 13–18
Magnetic fields of strongly magnetized stars can trap conducting matter due to frozen-in condition. In the force-free regime, the motion of the matter along the field lines may be considered in the 'bead on a wire' approximation. Such a motion, if gravity and centrifugal forces are taken into account, has equilibrium points, some of which ...
Added: October 31, 2022
Khokhryakova A. D., Biryukov A., Popov S. B., Astronomy Reports 2021 Vol. 65 No. 7 P. 615–630
A four-year sky survey with the use of the eROSITA telescope on board the Spektr-RG observatory with focusing optics will provide the best coverage in the soft (0.5-2 keV) and standard (2-10 keV) X-ray ranges, both in terms of sensitivity and angular resolution. We have investigated the possibility of detecting various types of single neutron ...
Added: October 31, 2022
Biryukov A., Abolmasov P., Monthly Notices of the Royal Astronomical Society 2021 Vol. 505 No. 2 P. 1775–1786
The rotation of a magnetized accreting neutron star (NS) in a binary system is described by its spin period and two angles: spin inclination α with respect to the orbital momentum and magnetic angle χ between the spin and the magnetic moment. Magnetospheric accretion spins the NS up and adjusts its rotation axis, decreasing α ...
Added: October 31, 2022
Gorban A., Мольков С. В., Цыганков С. С. et al., Письма в Астрономический журнал 2022 Т. 48 № 4 С. 279–289
The results of the broadband spectral and timing study of the transient X-ray pulsar GRO J2058+42 in a wide energy range at a low luminosity Lx ≃ 2.5 × 10^36 erg s^−1 are reported. The data revealed that the pulse profile and pulse fraction of the source are significantly changed in comparison with previous NuSTAR ...
Added: June 16, 2022
Samodurov V., Тюльбашев С. А., Торопов М. О. et al., Астрономический журнал 2022 Т. 99 № 4 С. 334–341
A search for impulse signals was carried out in a new site included in the monitoring program for the search for pulsars and transients. Processing of several months of data recorded in six frequency channels with a total bandwidth of 2.5 MHz showed that, on average, 4 pulses per hour are observed in each of ...
Added: April 23, 2022
Бисноватый-Коган Г. С., Kondratyev I., Успехи физических наук 2021 Т. 191 № 5 С. 543–557
The thermodynamic properties of electron gas under the extreme conditions of high temperature, high matter density, and/or a strong magnetic field largely determine the behavior of matter in upper layers of neutron stars and accretion columns of magnetized neutron stars in binary systems. A strong magnetic field in these objects makes the motion of electrons ...
Added: March 29, 2022
Gorban A., Мольков С. В., Цыганков С. С. et al., Письма в Астрономический журнал 2021 Т. 47 № 6 С. 416–427
We present the results of our spectral and timing analysis of the emission from the transient X-ray pulsar XTE J1946+274 based on the simultaneous NuSTAR and Swift/XRT observations in the broad energy range 0.3–79 keV carried out in June 2018 during a bright outburst. Our spectral analysis has confirmed the presence of a cyclotron absorption ...
Added: November 18, 2021
Sazonov S., Kulkarni S., Monthly Notices of the Royal Astronomical Society 2021 Vol. 508 No. 3 P. 3820–3847
We present the first sample of tidal disruption events (TDEs) discovered during the SRG all-sky survey. These 13 events were selected among X-ray transients detected in the 0° < l < 180° hemisphere by eROSITA during its second sky survey (2020 June 10 to December 14) and confirmed by optical follow-up observations. The most distant ...
Added: October 27, 2021
Beznogov M. V., Potekhin A. Y., Yakovlev D., Physics Reports 2021 Vol. 919 P. 1–68
Near the surface of any neutron star there is a thin heat blanketing envelope that produces substantial thermal insulation of warm neutron star interiors and that relates the internal temperature of the star to its effective surface temperature. Physical processes in the blanketing envelopes are reasonably clear but the chemical composition is not. The latter ...
Added: October 22, 2021
Kondratyev I., Moiseenko S. G., Бисноватый-Коган Г. С. et al., Астрономический журнал 2020 Т. 97 № 3 С. 206–224
The results of three-dimensional numerical simulation of heat transfer in the outer layers of magnetized neutron stars are presented. Determining the structure of the magnetic field on a neutron star surface is an important task of modern astrophysics. In the presence of strong magnetic fields, the medium becomes anisotropic, and the laws of heat conduction ...
Added: October 14, 2021
Kondratyev I., Moiseenko S. G., Бисноватый-Коган Г. С. et al., Monthly Notices of the Royal Astronomical Society 2020 Vol. 497 No. 3 P. 2883–2892
Determination of a magnetic field structure on a neutron star (NS) surface is an important problem of a modern astrophysics. In a presence of strong magnetic fields, a thermal conductivity of a degenerate matter is anisotropic. In this paper, we present 3D anisotropic heat transfer simulations in outer layers of magnetized NSs, and construct synthetic ...
Added: October 14, 2021
Ridnaia A., Svinkin D., Frederiks D. et al., NATURE ASTRONOMY 2021 Vol. 5
Fast radio bursts (FRBs) are bright, millisecond-scale radio flashes of unknown physical origin1. Young, highly magnetized, isolated neutron stars—magnetars—have been suggested as the most promising candidates for FRB progenitors owing to their energetics and high X-ray flaring activity2,3. Here we report the detection with Konus-Wind of a hard X-ray event of 28 April 2020 temporally ...
Added: March 24, 2021
Igoshev A., Popov S., Astronomische Nachrichten 2021 Vol. 342 No. 1-2 P. 216–221
The role of magnetic field decay in normal radio pulsars is still debated. In this paper, we present results which demonstrate that an episode of magnetic field decay in hot young neutron stars can explain anomalous values of braking indices recently measured for more than a dozen of sources. It is enough to have few ...
Added: March 24, 2021
Sazonov S., New Astronomy Reviews 2020 Vol. 88 P. 101536
Seventeen years of hard X-ray observations with the instruments of the INTEGRAL observatory, with a focus on the Milky Way and in particular on the Galactic Centre region, have provided a unique database for exploration of the Galactic population of low-mass X-ray binaries (LMXBs). Our understanding of the diverse energetic phenomena associated with accretion of ...
Added: November 16, 2020
Yakovlev D., International Journal of Modern Physics A 2020 Vol. 35 No. 2-3 P. 1–8
Neutron stars contain superdense matter in their interiors. Characteristic densities in their cores are several times higher than the standard density of nuclear matter. This matter is so dense that it would be natural to assume that frequent particle collisions produce immediate equilibration. However, because of the slowness of some reactions, the equilibration with respect ...
Added: November 13, 2020
Chaikin E. A., Kaminker A. D., Yakovlev D.G., Astrophysics and Space Science 2018 No. 363 P. 209
We study thermal relaxation in a neutron star after internal heating events (outbursts) in the crust. We consider thin and thick spherically symmetric heaters, superfluid and non-superfluid crusts, stars with open and forbidden direct Urca processes in their cores. In particular, we analyze long-term thermal relaxation after deep crustal heating produced by nuclear transformations in ...
Added: November 13, 2020
Гусаков М. Е., Кантор Е. М., Ofengeim D., Monthly Notices of the Royal Astronomical Society 2020 Vol. 499 No. 3 P. 4561–4569
The self-consistent approach to the magnetic field evolution in neutron star (NS) cores, developed recently, is generalized to the case of superfluid and superconducting NSs. Applying this approach to the cold matter of NS cores composed of neutrons, protons, electrons, and muons, we find that, similarly to the case of normal matter, an arbitrary configuration ...
Added: November 11, 2020