ﻻ يوجد ملخص باللغة العربية
We study a possible connection between processes of gamma-ray emission and hydrogen ionization in a few pc of central region around Sgr A*. Previous investigations showed there is a discrepancy between interpretation of gamma-ray and ionization data if gamma-rays are generated by proton-proton collisions. Here we provided analysis of processes of ionization and emission basing on analytical and numerical calculations of kinetic equations which describe processes of particle propagation and their energy losses. The origin of gamma rays could be either due to collisions of relativistic protons with the dense gas of the surrounding circumnuclear disk (CND) or bremsstrahlung and inverse Compton scattering of relativistic electrons. The hydrogen ionization in this case is produced by a low energy component of the CR spectrum. We found that if ionization is produced by protons the expected ionization rate of hydrogen in the CND is of the same order as derived from IR observations. So we do not see any discrepancy between the gamma-ray and ionization data for the hadronic model. In the case of ionization by electrons we obtained the ionization rate one order of magnitude higher than follows from the IR data. In principle, a selection between the leptonic and hadronic interpretations can be performed basing on measurements of radio and X-ray fluxes from this region because the leptonic and hadronic models give different values of the fluxes from there. We do not exclude that gamma-ray production and hydrogen ionization in the CND are due to a past activity of Sgr A* which occurred about 100 year ago. Then we hypothesize that there may be connection between a past proton eruption and a flux of hard X-rays emitted by Sgr A* hundred years ago as follows from the observed time variability of the iron line seen in the direction of GC molecular clouds.
We analyse the 6.4 keV iron line component produced in the Galactic Center (GC) region by cosmic rays in dense molecular clouds (MCs) and in the diffuse molecular gas. We showed that this component, in principle, can be seen in several years in the d
We report a new 1-pc (30) resolution CS($J=2-1$) line map of the central 30 pc of the Galactic Center (GC), made with the Nobeyama 45m telescope. We revisit our previous study of the extraplanar feature called polar arc (PA), which is a molecular clo
It has been recently proposed that the broad line region in active galactic nuclei originates from dusty clouds driven from the accretion disk by radiation pressure, at a distance from the black hole where the disk is cooler than the dust sublimation
Malin 1, being a class of giant low surface galaxies, continues to surprise us even today. The HST/F814W observation has shown that the central region of Malin 1 is more like a normal SB0/a galaxy, while the rest of the disk has the characteristic of
The empirical relations in the black hole-accretion disk-relativistic jet system and physical processes behind these relations are still poorly understood, partly because they operate close to the black hole within the central light year. Very long b