arXiv subjects

A. V. Tutukov

Publications and source records attributed to A. V. Tutukov.

25 records · Page 2Linked to original sources

arXiv2005

Evolution of Galaxies and the Tully-Fisher Relation

We study the evolution of the [O/Fe]-[Fe/H] relation and the dependence of the iron abundance on distance from the galactic plane z in a one-zone model for a disk galaxy, starting from the beginning of star formation (Wiebe98). We obtain good agreement with the observational data, including, for the first time, agreement for the [Fe/H]-z relation out to heights of 16 kpc. We also study the influence of the presence of dark matter in the galaxies on the star-formation rate. Comparison of the observed luminosity of the Galaxy with the model prediction places constraints on the fractional mass of dark matter, which cannot be much larger than the fractional mass of visible matter, at least within the assumed radius of the Galaxy, 20 kpc. We studied the evolution of disk galaxies with various masses, which should obey the Tully-Fisher relation, M \propto R^2. The Tully-Fisher relation can be explained as a combination of a selection effect related to the observed surface brightnesses of galaxies with large radii and the conditions for the formation for elliptical galaxies.

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arXiv2005

The Luminosity Function and Formation Rate History of GRBs

The isotropic luminosity function (LF) and formation rate history (FRH) of long GRBs is by the first time constrained by using jointly both the observed GRB peak-flux and redshift distributions. Our results support an evolving LF and a FRH that keeps increasing after z=2. We discuss some interesting implications related to these results.

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arXiv2004

Formation Rate, Evolving Luminosity Function, Jet Structure, and Progenitors for Long Gamma-Ray Bursts

We constrain the isotropic luminosity function (LF) and formation rate of long gamma-ray bursts (GRBs) by fitting models 'jointly' to both the observed differential peak flux and redshift distributions. We find evidence supporting an evolving LF, where the luminosity scales as (1+z)^delta with an optimal delta of 1.0\pm 0.2. For a single power-law LF, the best slope is ~ -1.57 with an upper luminosity of 10^53.3 erg/s, while the best slopes for a double power-law LF are approximately -1.6 and -2.6 with a break luminosity of 10^52.7 erg/s. Our finding implies a jet model intermediate between the universal structured epsilon(theta) proportional to theta^-2 model and the quasi-universal Gaussian structured model. For the uniform jet model our result is compatible with an angle distribution between 2 and 15 grades. Our best constrained GRB formation rate histories increase from z=0 to z=2 by a factor of ~30 and then continue increasing slightly. We connect these histories to that of the cosmic star formation history, and compare with observational inferences up to z~6. GRBs could be tracing the cosmic rates of both the normal and obscured star formation regimes. We estimate a current GRB event rate in the Milky Way of ~5 10^-5 yr^-1, and compare it with the birthrate of massive close WR+BH binaries with orbital periods of hours. The agreement is rather good suggesting that these systems could be the progenitors of the long GRBs.

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arXiv2003

Type Ia Supernovae in semi-detached binary systems

We have considered scenarios for the evolution of close binaries resulting in the formation of semi-detached systems in which a white dwarf can accumulate Chandrasekhar mass by accretion from a main-sequence or subgiant companion with $M\sim 2 M_\odot$. These white dwarfs, probably, explode as type Ia supernovae or collapse with formation of neutron stars. We have carried out a population synthesis study for these systems and have estimated the occurrence rate of such events in the Galaxy, depending on the parameter of common envelopes, mass-exchange rate in the binary, reaction of the main-sequence component on accretion of helium in the intervening phase of evolution. We have found that the model occurrence rate of SNe Ia in semi-detached systems is $\simeq 0.2 \times 10^{-3}$ yr$^{-1}$, i. e., it does not exceed $\sim 10%$ of the observational estimate of the Galactic occurrence rate of SNe Ia.

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arXiv2000

Non-conservative Evolution of Cataclysmic Variables

We suggest a new mechanism to account for the loss of angular momentum in binaries with non-conservative mass exchange. It is shown that in some cases the loss of matter can result in increase of the orbital angular momentum of a binary. If included into consideration in evolutionary calculations, this mechanism appreciably extends the range of mass ratios of components for which mass exchange in binaries is stable. It becomes possible to explain the existence of some observed cataclysmic binaries with high donor/accretor mass ratio, which was prohibited in conservative evolution models.

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arXiv1999

Synthesis of radioactive nuclei and gamma-line radiation from novae

We carried out kinetic calculations of thermonuclear burning in the hydrogen-rich matter to simulate nucleosynthesis yields in nova outbursts. These results are used to calculate the light curves of annihilation gamma-ray line from N, O and F radioactive isotopes.

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arXiv1999

Role of disk galaxies in the chemical enrichment of the intracluster medium

Elliptical galaxies are often assumed to be the primary source of heavy elements in the intracluster medium (ICM), with the contribution of other morphological types being negligible. In this paper we argue that a role of spiral galaxies in the chemical evolution of the ICM is also important. This statement rests upon our recent calculations of the heavy element loss from a disk galaxy through the hot steady-state galactic wind and dust grains expulsion by stellar radiation pressure. We show that a typical disk galaxy is nearly as effective in enriching the ICM as an elliptical galaxy of the same mass. Having estimated the oxygen and iron loss from a single galaxy, we integrate them over the galactic mass spectrum. We show that the "effective" loss (per unit luminosity) from spiral galaxies is comparable to the loss from ellipticals. The dominant role of early-type galaxies in rich clusters is caused by that they outnumber spirals.

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