Areg M. Mickaelian

High–redshift quasars and blazars and their relation to high–redshift galaxies

High–redshift quasars and blazars are among the most powerful sources in the Universe and among the highest luminosity sources, as in optical, so as in X–ray, UV, IR and radio range. We have created a full sample of blazars and high–redshift quasars (z 2.15). The evolutionary relation of high–redshift quasars and blazars to high–redshift galaxies is discussed using the luminosity evolution.

Radio Properties of AGN

To study the radio properties of AGN, we cross-correlate and investigate Veron-Cetty & Veron catalog of QSOs and Active Galaxies (v.13, 2010) with a number of radio catalogs: NVSS, FIRST, GB6, 87GB, SUMSS, WISH, WENSS, and 7C. This catalog contains 168,940 objects with positional accuracy of mostly 1 arcsec, though many positions have larger errors. We use new cross-correlation software based on accuracy of each object independently. In this software we take into account errors for each source and take identifications with errors within 3 sigma. Altogether, we find ∼16,000 AGN having radio detection in any of the listed catalogs. Using all data from radio catalogs, we derive a homogeneous sample of radio AGN. The sample allows accomplish several tasks, including study of the distribution of radio sources by activity types, differences in physical properties of radio-loud and radio-quiet AGN, luminosity functions for various types of radio AGN, study of the q parameter by AGN types and its evolution, etc.

Activity types for X-ray candidate AGN from SDSS

The Joint Catalogue of Hamburg ROSAT Sources (HRC/BHRC) is the result of merging of HRC and BHRC catalogs built on the basis of optical identifications of ROSAT BSC and ROSAT FSC. Altogether, 8132 sources are present. Based on this catalogue, we have compiled a sample of ROSAT AGN, including candidate ones. In this paper we classify candidate AGN (those that previously had not been spectroscopically classified) by their activity type. The sample contains 955 objects with count rate of photons CR > 0.04 ct/s in the area with galactic latitudes |b| > 30 and declinations δ > 0, however only 217 objects have SDSS DR10 spectra. The classification led to the following results: 95 AGN, 71 absorption-line galaxies, 42 stars, and 9 unclassified objects.

Study of Starburst/Activity/Interaction Phenomena based on the Multiple Byurakan-IRAS Galaxies

The Byurakan-IRAS Galaxy (BIG) sample is the result of optical identifications of IRAS PSC sources at high-galactic latitudes using the First Byurakan Survey (FBS) low-dispersion spectra. Among the 1178 objects most are spiral galaxies and many have been proved to be AGN and starburst by spectroscopic observations, as well as there is a number of ULIRGs among these objects. BIG objects contain galaxy pairs, multiples, and small groups that are subject for study on the matter of the real IR-emitter in these systems. Given that these objects are powerful IR sources, they are considered as young systems indicating high rate of evolution and starburst activity exceeding 100 M o /yr. Spectroscopic observations show that all these systems are physical ones and we were able to measure the mutual distances and sizes for all components. Cross-correlations with the recent more accurate IR catalogues, such as 2MASS and WISE, as well as radio ones (NVSS, FIRST), provided accurate coordinates of the IR source and possibility to find the individual galaxy responsible for the IR. However, in almost half of the cases, IR position indicates the intermediate region between the components, which means that it comes from the system as a whole. Some more MW data have been matched to IR and radio to have an overall understanding on these systems. Given that these systems are mostly interacting/merging ones often containing AGN and most of them may be considered as powerful starbursts, it is possible to study starburst/activity/interaction phenomena and their interrelationship.

Markarian survey and Markarian galaxies

Markarian survey (or the First Byurakan Survey, FBS) was the first systematic survey for active galaxies and was a new method for search for such objects. Until now, it is the largest objective prism survey of the sky (17,000 deg 2 ). It was carried out in 1965–1980 by B. E. Markarian and his colleagues and resulted in discovery of 1517 UV-excess (Markarian) galaxies. They contain many active galaxies, as well as powerful gamma-, X-ray, IR and radio sources (Mrk 180, 231, 421, 501, etc.), BCDGs (Mrk 116) and interacting/merging systems (Mrk 266, 273, etc.). They led to the classification of Seyfert galaxies into Sy1 and Sy2 and the definition of Starbursts (SB). Several catalogs of Markarian galaxies have been published (Mazzarella & Balzano 1986; Markarian et al . 1989; Bicay et al . 1995; Petrosian et al . 2007) and they are accessible in all corresponding databases. Markarian survey also served as a basis for search for UVX stellar objects (including QSOs and Seyferts), late-type stars and optical identification of IR sources. At present the survey is digitized and DFBS database is available. I will review the main characteristics of the Markarian survey, its comparison with other similar surveys and the importance of Markarian galaxies in modern astrophysics.

The ROSAT/NVSS AGN sample

Byurakan Astrophysical Observatory (BAO), Byurakan 0213, Aragatzotn province, ArmeniaEmail: gurgen@bao.sci.am, abrahamyanhayk@gmail.com, goharutyunyan@gmail.com,aregmick@aras.amAbstract. We attempt to create an X-ray/radio AGN catalog and make its multiwavelengthstudies. ROSAT Bright Source Catalogue (BSC) contains 18,806 and ROSAT Faint Source Cat-alogue (FSC), 105,922 X-ray sources giving the total number of ROSAT X-ray sources 124,727(one source is listed twice). On the other hand, NVSS radio catalogue contains 1,773,484 sources.Taking into account that X-ray sources contain AGN, bright stars and galaxies, clusters, whitedwarfs (WD), cataclysmic variables (CV), etc., the cross-identification with radio catalogue maydistinguish the extragalactic sources. We have cross-correlated ROSAT catalogs with NVSS onewith a search radius 30 arcsec. 9,193 associations have been found. To distinguish AGN fromthe normal bright galaxies and clusters, Veron-Cetty & Veron AGN catalog (v.13, 2010; VCV-13) containing 168,940 objects have been used. A cross-correlation of the 9,193 ROSAT/NVSSsources with the VCV-13 with a search radius 30 arcsec resulted in 3,094 associations. Thus weare left with more 6,099 X-ray/radio sources without an optical identification. Brighter objectsare normal bright galaxies, while we believe that all faint ones are candidate AGN with somecontamination of distant clusters. SDSS spectroscopic survey allows us classify objects by ac-tivity types, and a number of our candidate AGN is found to be present in SDSS. We attemptto find connections between the fluxes in different wavelength ranges, which will allow us toconfirm AGN and blazars candidates and in some cases find new ones.Keywords. X-ray and radio surveys, SDSS, cross-correlations, AGN, AGN candidates

Study of a homogeneous X-ray selected AGN sample

Based on optical identifications of ROSAT sources, we have created a large homogeneous catalog of X-ray selected AGN. The Hamburg-RASS Catalog (HRC) and ByurakanHamburg-RASS Catalog (BHRC) made up on the basis of optical identification of X-ray sources from ROSAT Bright Source (BSC) and Faint Source (FSC) catalogues, respectively, have been used. These identiifcations were based on low-dispersion spectra of Hamburg Quasar Survey (HQS). As a result, a new large sample of X-ray selected AGN has been compiled containing 4253 sources with photon count rate CR > 0.04 ct/s in the area with galactic latitudes |b| > 20 and declinations δ > 0. All these sources are classified as AGN or candidate AGN. We have carried out multiwavelength studies in several wavelength ranges (X-ray, optical, radio). Catalogues that more or less guarantee the completeness condition (all-sky or large area surveys) were used. A number of erroneous classifications were found (some AGN had been classified as stars or galaxies); 1024 and 59 from HRC and BHRC, respectively. Out of 4253 sources, 3352 are spectroscopically confirmed AGN (given in Veron-Cetty & Veron and Roma Blazar catalogs), and the rest 901 are candidate AGN. For 210 of them spectra are available in SDSS DR9, and the results of their classification are given in another paper. We calculated absolute magnitudes, fluxes, improved coordinates and redshifts. An attempt is made to find a connection between the radiation fluxes in different bands for different types of sources, and identify their typical characteristics, thus confirming candidate AGN and in some cases finding new ones.