Ambartsumian Byurakan Astrophysical Observatory

Aragatsotn, Armenia

Ambartsumian Byurakan Astrophysical Observatory

Aragatsotn, Armenia
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Harutyunian H.,Ambartsumian Byurakan Astrophysical Observatory | Alecian G.,University Paris Diderot | Khachatryan K.,Ambartsumian Byurakan Astrophysical Observatory | Vardanyan A.,Ambartsumian Byurakan Astrophysical Observatory
Journal of Quantitative Spectroscopy and Radiative Transfer | Year: 2016

We suggest here a method for construction of a bilinear expansion for an angle-averaged redistribution function. This function describes the elementary act of a photon scattering by a model two-level atom with the upper level broadened due to radiation damping. An eigenvalue and eigenvector determination problem is formulated and the relevant matrices are found analytically. Numerical procedures for their computations are elaborated as well. A simple method for the numerical calculations accuracy evaluation is suggested. It is shown that a family of redistribution functions describing the light scattering process within the spectral line frequencies can be constructed if the eigenvalue problem for the considered function is solved. It becomes possible if the eigenvalues and eigenvectors with the appropriate basic functions are used. The Voigt function and its derivatives used as basic functions are studied in detail as well. © 2016


Ter-Kazarian G.,Ambartsumian Byurakan Astrophysical Observatory
Physics Research International | Year: 2015

In the framework of proposed theory of spacetime deformation/distortion, we have a way to deform the spacetime through a nontrivial choice of the distortion-complex, displaying different connections, which may reveal different post-Riemannian spacetime structures as corollary. We extend this theory to address, in particular, the gauge model of the most general metric-affine gravity carrying both nontrivial torsion and nonmetricity. This model is constructed in the framework of the first order Lagrangian expressed in terms of the gauge potentials and their first derivatives. The equations of the standard theory, which have no propagating modes for torsion, can be equivalently replaced in modified framework by the modified equations, which in the limit of reducing the affine group leads to the modified Einstein-Cartan theory with dynamical torsion and beyond. In testing the modified framework for various particular cases, we use the Lagrange multipliers for extinguishing nonmetricity and torsion. © 2015 Gagik Ter-Kazarian.


Nikoghossian A.,Ambartsumian Byurakan Astrophysical Observatory
Journal of Quantitative Spectroscopy and Radiative Transfer | Year: 2016

The paper presents a group-theoretical description of radiation transfer in inhomogeneous and multi-component atmospheres with the plane-parallel geometry. It summarizes and generalizes the results obtained recently by the author for some standard transfer problems of astrophysical interest with allowance of the angle and frequency distributions of the radiation field. We introduce the concept of composition groups for media with different optical and physical properties. Group representations are derived for two possible cases of illumination of a composite finite atmosphere. An algorithm for determining the reflectance and transmittance of inhomogeneous and multi-component atmospheres is described. The group theory is applied also to determining the field of radiation inside an inhomogeneous atmosphere. The concept of a group of optical depth translations is introduced. The developed theory is illustrated with the problem of radiation diffusion with partial frequency distribution assuming that the inhomogeneity is due to depth-variation of the scattering coefficient. It is shown that once reflectance and transmittance of a medium are determined, the internal field of radiation in the source-free atmosphere is found without solving any new equations. The transfer problems for a semi-infinite atmosphere and an atmosphere with internal sources of energy are discussed. The developed theory allows to derive summation laws for the mean number of scattering events underwent by the photons in the course of diffusion in the atmosphere. © 2016 Elsevier Ltd.


Ter-Kazarian G.,Ambartsumian Byurakan Astrophysical Observatory
Astrophysics and Space Science | Year: 2016

To reconcile the observed unusual high luminosity of NuSTAR X-ray pulsations from M82X-2 with the most extreme violation of the Eddington limit, and in view that the persistent X-ray radiation from M82X-2 almost precludes the possibility of common pulsars, we tackle the problem by the implications of microscopic theory of black hole (MTBH). The preceding developments of MTBH are proved to be quite fruitful for the physics of ultra-high energy (UHE) cosmic-rays. Namely, replacing a central singularity by the infrastructures inside event horizon, subject to certain rules, MTBH explains the origin of ZeV-neutrinos which are of vital interest for the source of UHE-particles. The M82X-2 is assumed to be a spinning intermediate mass black hole resided in final stage of growth. Then, the thermal blackbody X-ray emission, arisen due to the rotational kinetic energy of black hole, escapes from event horizon through the vista to outside world, which is detected as ultraluminous X-ray pulsations. The M82X-2 indeed releases ∼99.6% of its pulsed radiative energy predominantly in the X-ray bandpass 0.3–30 keV. We derive a pulse profile and give a quantitative account of energetics and orbital parameters of the semi-detached X-ray binary containing a primary accretor M82X-2 of inferred mass (formula presented) and secondary massive, (formula presented), O/B-type donor star with radius of (formula presented), respectively. We compute the torque added to M82X-2 per unit mass of accreted matter which yields the measured spin-up rate. © 2015, Springer Science+Business Media Dordrecht.

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