122 citations · 954 across the 47 of their papers we have counts for
10 papers · 1 filter
Comparison of the spatial and the angular clustering of X-ray AGN
L. Koutoulidis, M. Plionis, I. Georgantopoulos +4
The angular correlation function is a powerful tool for deriving the clustering properties of AGN and hence the mass of the corresponding dark matter halos in which they reside. Ho…
A wide search for obscured Active Galactic Nuclei using XMM-Newton and WISE
E. Rovilos, I. Georgantopoulos, A. Akylas +8
We use a combination of the XMM-Newton serendipitous X-ray survey with the optical SDSS, and the infrared WISE all-sky survey in order to check the efficiency of the low X-ray to i…
On the Lx-L6micron ratio as a diagnostic for Compton-thick AGN
I. Georgantopoulos, E. Rovilos, A. Akylas +6
As the mid-IR luminosity represents a good isotropic proxy of the AGN power, a low X-ray to mid-IR luminosity ratio is often claimed to be a reliable indicator for selecting Compto…
X-ray observations of highly obscured 9.7 micron sources: an efficient method for selecting Compton-thick AGN ?
I. Georgantopoulos, K. M. Dasyra, E. Rovilos +8
Spitzer/IRS has revealed many sources with very deep Si features at 9.7micron (tau>1). We set out to investigate whether a strong Si absorption feature is a good indicator for the…
Molecular lines as tracers of Compton-thick AGN ?
I. Georgantopoulos, E. Rovilos, A. Akylas +1
Recently, Papadopoulos et al., 2010 using sub-mm CO molecular line observations of nearby ultra-luminous IRAS galaxies, (U)LIRGs, have found that exceptionally large gas column den…
X-ray selected Infrared Excess AGN in the Chandra Deep Fields: a moderate fraction of Compton-thick sources
I. Georgantopoulos, E. Rovilos, E. M. Xilouris +2
We examine the properties of the X-ray detected, Infrared Excess AGN or Dust Obscured Galaxies (DOGs) in the Chandra Deep Fields (CDF). We find 26 X-ray selected sources which obey…
Optically faint X-ray sources in the CDFN: Spitzer constraints
E. Rovilos, I. Georgantopoulos, A. Akylas +1
We investigate the properties of the most optically faint sources in the GOODS-N area (R > 26.5 AB). Such extremely optically faint populations present an uncharted territory despi…
Comparison between the Luminosity functions of X-ray and [OIII] selected AGN
I. Georgantopoulos, A. Akylas
We investigate claims according to which the X-ray selection of AGN is not as efficient compared to that based on [OIII] selection because of the effects of X-ray absorption.We con…
The Compton-thick AGN in the CDF-N
I. Georgantopoulos, A. Akylas, A. Georgakakis +1
We present X-ray spectral analysis of the brightest sources (f_{2-10 keV}>10^{-15}$ cgs) in the Chandra Deep Field North. Our sample consists of 222 sources; for the vast majority…
XMM-Newton observations of Seyfert galaxies from the Palomar spectroscopic survey: the X-ray absorption distribution
A. Akylas, I. Georgantopoulos
We present XMM-Newton spectral analysis of all 38 Seyfert galaxies from the Palomar spectroscopic sample of galaxies. These are found at distances of up to 67 Mpc and cover the abs…