Jose Miguel Mas-Hesse

The second INTEGRAL AGN catalogue

Aims. The INTEGRAL mission provides a large data set for studying the hard X-ray properties of AGN and allows testing of the unified scheme for AGN. Methods. We present analysis of INTEGRAL IBIS/ISGRI, JEM-X, and OMC data for 199 AGN supposedly detected by INTEGRAL above 20 keV. Results. The data analysed here allow significant spectral extraction on 148 objects and an optical variability study of 57 AGN. The slopes of the hard X-ray spectra of Seyfert 1 and Seyfert 2 galaxies are found to be consistent within the uncertainties, whereas higher cut-off energies and lower luminosities we measured for the more absorbed/type 2 AGN. The intermediate Seyfert 1.5 objects exhibit hard X-ray spectra consistent with those of Seyfert 1. When applying a Compton reflection model, the underlying continua appear the same in Seyfert 1 and 2 with Γ � 2, and the reflection strength is about R � 1, when assuming different inclination angles. A significant correlation is found between the hard X-ray and optical luminosity and the mass of the central black hole in the sense that the more luminous objects appear to be more massive. There is also a general trend toward the absorbed sources and type 2 AGN having lower Eddington ratios. The black hole mass appears to form a fundamental plane together with the optical and X-ray luminosity of the form LV ∝ L 0.6 X M 0.2 BH , similar to what is found between LR, LX ,a ndMBH. Conclusions. The transition from the type 1 to type 2 AGN appears to be smooth. The type 2 AGN are less luminous and have less accreting super massive black holes. The unified model for Seyfert galaxies seems to hold, showing in hard X-rays that the central engine is the same in Seyfert 1 and 2, but seen under different inclination angles and absorption. The fundamental plane links the accretion mechanism with the bulge of the host galaxy and with the mass of the central engine in the same way in all types of Seyfert galaxies.

The Second IBIS/ISGRI Soft Gamma-Ray Survey Catalog

In this paper we report the second soft gamma-ray source catalog obtained with the IBIS/ISGRI gamma-ray imager on board the INTEGRAL satellite. The scientific data set is based on more than 10 Ms of high-quality observations performed during the first 2 years of Core Program and public IBIS/ISGRI observations, and covers ~50% of the whole sky. The main aim of the first survey was to scan systematically, for the first time at energies above 20 keV, the whole Galactic plane to achieve a limiting sensitivity of ~1 mcrab in the central radian. The target of the second year of the INTEGRAL mission lifetime was to expand as much as possible our knowledge of the soft gamma-ray sky, with the same limiting sensitivity, to at least 50% of the whole sky, mainly by including a substantial coverage of extragalactic fields. This catalog comprises more than 200 high-energy sources detected in the energy range 20-100 keV, including new transients not active during the first year of operation, faint persistent objects revealed with longer exposure time, and several Galactic and extragalactic sources in sky regions not observed in the first survey. The mean position error for all the sources detected with significance above 10 ? is ~40, enough to identify most of them with a known X-ray counterpart and to unveil the nature of most of the strongly absorbed ones, even though they are very difficult to detect in X-rays.

Nuclear Activity and Massive Star Formation in the Low-Luminosity Active Galactic Nucleus NGC 4303: Chandra X-Ray Observations

We present evidence of the coexistence of either an AGN or an ultraluminous X-ray source, together with a young superstellar cluster, in the central 3 pc of NGC 4303. The galaxy contains a low-luminosity AGN and hosts a number of starburst regions in a circumnuclear spiral, as well as in the nucleus itself. A high spatial resolution Chandra image of this source reveals that the soft X-ray emission traces the ultraviolet nuclear spiral down to a core, which is unresolved in both soft and hard X-rays. The astrometry of the X-ray core coincides with the UV core within the Chandra positioning accuracy. The total X-ray luminosity of the core, ~1.5 × 1039 ergs s-1, is similar to that from some LINERs or from the weakest Seyfert galaxies detected so far. The soft X-rays in both the core and the extended structure surrounding it can be well reproduced by evolutionary synthesis models (which include the emission expected from single stars, the hot diffuse gas, supernova remnants, and binary systems), consistent with the properties of the young stellar clusters identified in the UV. The hard X-ray tail detected in the core spectrum, however, most likely requires the presence of an additional source. This additional source could be either a weak active nucleus black hole or an ultraluminous X-ray object. The implications of these results are discussed.

The High-Energy Emission of GRO J1655–40 As Revealed with INTEGRAL Spectroscopy of the 2005 Outburst

We present broadband (3-500 keV) INTEGRAL X-ray spectra and X-ray/optical light curves of the luminous black hole X-ray transient and relativistic jet source GRO J1655-40. Our analysis covers four Target of Opportunity observations of the outburst that started in 2005 February. We find that the high-energy emission of GRO J1655-40 can be modeled well with an unbroken power law (with photon indices Gamma of 1.72+/-0.03 and 2.21+/-0.04 for the first and second observations). These correspond to hard and thermal-dominant states, respectively. In contrast to many other black hole spectra, high-energy complexity in the form of a break or cutoff is not required for the hard state, contrary to previous expectations. We show for the first time that Comptonization by nonthermal electrons is the dominant process behind the high-energy emission in the hard state. We discuss our results in terms of models for broadband emission and accretion flows in stellar-mass black holes.

First Catalogue of Optically Variable Sources Observed by OMC Onboard INTEGRAL

In this work, we present the first catalogue of optically variable sources observed by the Optical Monitoring Camera (OMC), with information about the variability of more than 5000 objects and periodicity of ~ 1000 sources.

The unified scheme seen with INTEGRAL detected AGN

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 detected in slightly flatter spectra with higher cut‐off energies and lower luminosities for the type 2 AGN. When applying a Compton reflection model, the underlying continua (Γ≃1.95) appear the same in Seyfert 1 and 2, and the reflection strength is R≃1 in both cases, with differences in the inclination angle only. More luminous objects appear to be more massive and there is also a general trend for the absorbed sources and type 2 AGN to have lower Eddington ratios. The number counts are consistent with no evolution of the observed AGN. The unified model for Seyfert galaxies seems to hold, showing in hard X‐rays that the central engine is the same in Seyfert 1 and 2 galaxies, seen under different inclination angle and absorption.