arXiv subjects

A. I. Bogomazov

Publications and source records attributed to A. I. Bogomazov.

26 records · Page 2Linked to original sources

arXiv2009

Magnetars, Gamma-ray Bursts, and Very Close Binaries

We consider the possible existence of a common channel of evolution of binary systems, which results in a gamma-ray burst during the formation of a black hole or the birth of a magnetar during the formation of a neutron star. We assume that the rapid rotation of the core of a collapsing star can be explained by tidal synchronization in a very close binary. The calculated rate of formation of rapidly rotating neutron stars is qualitatively consistent with estimates of the formation rate of magnetars. However, our analysis of the binarity of newly-born compact objects with short rotational periods indicates that the fraction of binaries among them substantially exceeds the observational estimates. To bring this fraction into agreement with the statistics for magnetars, the additional velocity acquired by a magnetar during its formation must be primarily perpendicular to the orbital plane before the supernova explosion, and be large.

astro-ph.HE↗

arXiv2009

Merging of Components in Close Binaries: Type Ia Supernovae, Massive White Dwarfs, and Ap stars

The "Scenario Machine" (a computer code designed for studies of the evolution of close binaries) was used to carry out a population synthesis for a wide range of merging astrophysical objects: main-sequence stars with main-sequence stars; white dwarfs with white dwarfs, neutron stars, and black holes; neutron stars with neutron stars and black holes; and black holes with black holes.We calculate the rates of such events, and plot the mass distributions for merging white dwarfs and main-sequence stars. It is shown that Type Ia supernovae can be used as standard candles only after approximately one billion years of evolution of galaxies. In the course of this evolution, the average energy of Type Ia supernovae should decrease by roughly 10%; the maximum and minimum energies of Type Ia supernovae may differ by no less than by a factor of 1.5. This circumstance should be taken into account in estimations of parameters of acceleration of the Universe. According to theoretical estimates, the most massive - as a rule, magnetic - white dwarfs probably originate from mergers of white dwarfs of lower mass. At least some magnetic Ap and Bp stars may form in mergers of low-mass main sequence stars (<1.5 mass of the Sun) with convective envelopes.

astro-ph.SR↗

arXiv2008

Long Gamma-Ray Bursts and the Morphology of their Host Galaxies

We present the results of population syntheses for binary stars carried out using the ``Scenario Machine'' code with the aim of analyzing events that may result in long gamma-ray bursts. We show that the observed distribution of morphological types of the host galaxies of long gamma-ray bursts can be explained in a model in which long gamma-ray bursts result from the core collapse of massive Wolf-Rayet stars in close binaries. The dependence of the burst rate on galaxy type is associated with an increase in the rate of stellar-wind mass-loss with increasing stellar metallicity. The separation of binary components at the end of their evolution increases with the stellar-wind rate, resulting in a reduction of the number of binaries that produce gamma-bursts.

astro-ph↗

arXiv2008

Modeling the Wind of the Be Star SS 2883

Observations of eclipses of the radio pulsar B1259-63 by the disk of its Be-star companion SS 2883 provide an excellent opportunity to study the winds of stars of this type. The eclipses lead to variations in the radio flux (due to variations in the free-free absorption), dispersion measure, rotation measure, and linear polarization of the pulsar. We have carried out numerical modeling of the parameters of the Be-star wind and compared the results with observations.

astro-ph↗

arXiv2007

Description of the Scenario Machine

We present here an updated description of the "Scenario Machine" code. This tool is used to carry out a population synthesis of binary stars. Previous version of the description can be found at http://xray.sai.msu.ru/~mystery//articles/review/contents.html

astro-ph↗

arXiv2007

Luminosity function of binary X-ray sources calculated using the Scenario Machine

Using the ``Scenario Machine'' we have carried out a population synthesis of X-ray binaries for the purpose of modelling of X-ray luminosity functions (XLFs) in different types of galaxies: star burst, spiral, and elliptical. This computer code allows to calculate, by using Monte Carlo simulations, the evolution of a large ensemble of binary systems, with proper accounting for the spin evolution of magnetized neutron stars. We show that the XLF has no universal type. It depends on the star formation rate in the galaxy. Also it is of importance to take into account the evolution of binary systems and life times of X-ray stages in theoretical models of such functions. We have calculated cumulative and differential XLFs for the galaxy with the constant star formation rate. Also we have calculated cumulative luminosity functions for different intervals of time after the star formation burst in the galaxy and curves depicting the evolution of the X-ray luminosity after the star formation burst in the galaxy.

astro-ph↗

arXiv2006

Collapse of rotating stars in the Universe and the cosmic gamma ray bursts

We analyze here late evolutionary stages of massive (with initial mass higher than 8 masses of the Sun) close binary stars. Our purposes are to study possible mechanisms of gamma ray bursts (GRBs) origin. We suppose in this paper that GRB phenomenon require formation of massive (approx. 1 M_sun) compact (approx. 10 km) accretion disks around Kerr black holes and neutron stars. Such Kerr black holes are products of collapse of Wolf-Rayet stars in extremely close binaries and merging of neutron stars with black holes and neutron stars with neutron stars in close binary systems. Required accretion disks also can be formed around neutron stars which were formed during collapse of accreting oxygen-neon white dwarfs. We have estimated frequencies of events which lead to a rotational collapse concerned with formation of rapidly rotating relativistic objects in the Galaxy. We made our calculations using the "Scenario Machine".

astro-ph↗

arXiv2005

How is Binary Radio-Pulsars with Black Holes Population Rich?

Using "Scenario Machine" we have carried out population synthesis of radio pulsar with black hole binaries (BH+Psr) in context of the most wide assumptions about star mass loss during evolution, binary stars mass ratio distribution, kick velocity and envelope mass lost during collapse. Our purpose is to display that under any suppositional parameters of evolution scenario BH+Psr population have to be abundant in Galaxy. It is shown that in the all models including models evolved by Heger et al. (2002), Woosley et al. (2002), Heger et al. (2003) expected number of the black holes paired with radio pulsars is sufficient enough to discover such systems within the next few years.

astro-ph↗