arXiv subjects

G. M. Paronyan

Publications and source records attributed to G. M. Paronyan.

3 recordsLinked to original sources

arXiv2026

Distribution of the magnetic field relative to the plane of the Galaxy in the region of the Sagittarius spiral arm

Faraday rotation data for 492 pulsars and more than 2,700 extragalactic radio sources were used to study the magnetic field, in detail, in the direction of Galactic longitude $33^o$ <l< $63^o$, which partially covers the Sagittarius spiral arm region. It was proposed that the Sagittarius spiral arm lies north of the h=-300 pc plane, where h is the distance from the Galactic plane. The (-) sign indicates that this plane is located in the southern hemisphere of the Galaxy. The magnetic field of the Sagittarius spiral arm is directed toward the Sun. This direction is close to the direction of the magnetic field of the northern hemisphere halo. The small absolute value of the rotation measures in the region south of the h=-300 pc plane is due solely to the contribution of the magnetic field of the southern hemisphere halo, which is directed opposite to the field of the northern hemisphere halo and the direction of the field in the Sagittarius arm. In the interarm region between the local Orion arm and the Sagittarius arm, the halo magnetic field extends to the Galactic plane, where a reversal of the magnetic fields of the halos of the northern and southern hemispheres occurs.

astro-ph.GA↗

arXiv2018

On the magnetic field inside the solar circle of the Galaxy: On the possibility of investigation some of characteristics of the interstellar medium with using of pulsars with large Faraday rotation values

To study some characteristics of the interstellar medium, observational data of pulsars with large Faraday rotation values (|RM|> 300 rad / m2) were used. It was suggested and justified that large |RM| values can be due to the contribution of the regions with increased electron concentration, projected on the pulsar. Most likely these are the HII regions, dark nebulae and molecular clouds. In these objects the magnetic field can be oriented in the direction of a large-scale field of the Galaxy, or simply is a deformed extension of the galactic field. It was shown that the Galactic distribution of rotation measures of pulsars with |RM|> 300rad / m2 corresponds to the circular model of the magnetic field of the Galaxy, with the counter-clockwise direction of the magnetic field in the galactocentric circle 5 kpc <R <7 kpc.

astro-ph.GA↗

arXiv2015

Multiwavelength studies of X-ray selected extragalactic sample

The joint catalogue of Active Galactic Nuclei selected from optical identifications of X-ray sources was created as a combination of two samples: Hamburg-ROSAT Catalogue (HRC) and Byurakan-Hamburg-ROSAT Catalogue (BHRC). Both are based on optical identifications of X-ray sources from ROSAT catalogues using low-dispersion spectra of Hamburg Quasar Survey (HQS). However, HRC and BHRC contain a number of misidentifications and using the recent optical and multiwavelength (MW) catalogues we have revised both samples excluding false AGN and adding new genuine ones. Thus a new large homogeneous complete sample of 4253 X-ray selected AGN was created. 3352 of them are listed in the Catalogue of QSOs and Active Galaxies and 387 also are in Roma Multifrequency Catalogue of Blazars. 901 candidate AGN are subject for further study. We classified 173 of these objects using their SDSS DR12 spectra. Following activity types were revealed: 61 AGN, 21 HII galaxies, 12 emission-line galaxies without definite type, 71 absorption-line galaxies, 2 stars, and 6 were classified as "Unknown". A special emphasis is made on narrow-line Sy1.0-Sy1.5 galaxies and QSOs, as many of them have soft X-ray, strong FeII lines, and relatively narrow lines coming from BLR ("narrow broad lines"). As a result, the sample of genuine AGN was enlarged to 3413 objects. We have retrieved MW data from recent catalogues and carried out statistical investigations for the whole AGN sample. An attempt to find connections between fluxes in different bands for different types of sources, and identify their characteristics thus confirming candidate AGNs have been carried out. We have analyzed X-ray properties of these sources to find a limit between normal galaxies and X-ray AGN.

astro-ph.GA↗