Related papers: Unveiling the nature of INTEGRAL objects through o…

This paper presents new Chandra and BeppoSAX observations aimed at investigating the optical/X-ray mismatch in the enigmatic class of the Composite galaxies, discovered by a cross-correlation of IRAS and ROSAT all sky survey catalogues.…

The third INTEGRAL/IBIS survey has revealed several new hard X-ray sources, which are still unclassified. To identify these sources, we need to find their counterparts at other wavelengths and then study their nature. The capability of XRT…

We present the results of a program of optical and near-infrared spectroscopic follow-up of candidate Active Galactic Nuclei (AGN) selected in the mid-infrared. This survey selects both normal and obscured AGN closely matched in luminosity…

We report on 0.3-10 keV X-ray observations by the Chandra X-ray Observatory of the fields of 22 sources that were discovered as hard X-ray (20-100 keV) sources by the INTEGRAL satellite (IGR sources). The purpose of the Chandra observations…

Through an optical campaign performed at 4 telescopes located in the northern and the southern hemispheres, plus archival data from two on-line sky surveys, we have obtained optical spectroscopy for 29 counterparts of unclassified or poorly…

Using Spitzer-IRS spectroscopy, we investigate the ubiquity of Active Galactic Nuclei (AGN) in a complete (~94%), volume-limited sample of the most bolometrically-luminous galaxies (L_IR > (0.3-20) x 10^10 L_sun) to D < 15 Mpc. Our analyses…

We present the first X-ray observations of three sources belonging to a new AGN class: the naked AGNs. Based on optical spectroscopic studies, these sources appear as classical type 2 (obscured) AGNs, with only narrow emission lines.…

The European gamma-ray observatory INTEGRAL has found a group of hard X-ray sources which are highly absorbed, i.e., with column densities higher than about 10^{23}/cm^2. Here I give an overview of this class of INTEGRAL sources. The X-ray,…

After more than 5.5 years of in flight lifetime, the ESA space observatory INTEGRAL is depicting a new scenario in the soft gamma Ray domain. With the observation and discovery of more than 400 hard X-Ray sources has changed our view of a…

Based on a comparison of the SRG/eROSITA catalog of X-ray active stars and the Gaia catalog, a sample of 502 peculiar objects was obtained for which Gaia, on one hand, detects statistically significant values of parallax or proper motion…

We present the results of our identification of 17 X-ray sources detected in the 4-12 keV energy range by the Mikhail Pavlinsky ART-XC telescope during the first year of the SRG all-sky survey. Three of them have been discovered by the…

We present the preliminary results of the observational campaign performed in 2003 to study the Galactic Nucleus with INTEGRAL. The mosaicked images obtained with the IBIS/ISGRI coded aperture instrument in the energy range above 20 keV,…

We have conducted low-frequency radio observations with the Giant Metrewave Radio Telescope (GMRT) of 40 new hard X-ray sources discovered by the INTEGRAL satellite. This survey was conducted in order, to study radio emissions from these…

We studied spectra for 34 accretion-powered X-ray and one millisecond pulsars that were within the field of view of the INTEGRAL observatory over two years (December 2002 - January 2005) of its in-orbit operation and that were detected by…

We collect data at all frequencies for the new sources classified as unknown active galactic nuclei (AGNs) in the latest Burst Alert Telescope (BAT) all-sky hard X-ray catalog. Focusing on the 36 sources with measured redshift, we compute…

Our goal is to characterize AGN populations by comparing their X-ray and optical classifications. We present a sample of 99 spectroscopically identified X-ray point sources in the XMM-LSS survey which are significantly detected in the…

We present the results of our identification of 11 X-ray sources detected on the half of the sky $0^\circ<l<180^\circ$ in the 4-12 keV energy band on the combined map of the first five all-sky surveys with the Mikhail Pavlinsky ART-XC…

The NuSTAR Legacy program 'Unidentified INTEGRAL sources' targeted faint hard X-ray sources revealed by INTEGRAL in the Galactic plane in order to provide conclusive identification of their nature and insights on the population of faint…

A new type of high-energy binary system has been revealed by the INTEGRAL satellite. These sources are being unveiled by means of multi-wavelength optical, near- and mid-infrared observations. Among these sources, two distinct classes are…

The INTEGRAL mission provides a large data set for studying the hard X-ray properties of AGN and allows to test the unified scheme for AGN. We present results based on the analysis of 199 AGN. A difference between the Seyfert types is…