INTIBISAGN - INTEGRAL IBIS AGN Catalog

Overview

In this work, the authors present the most comprehensive INTEGRAL active galactic nucleus (AGN) sample. It lists 272 AGN for which they have secure optical identifications, precise optical spectroscopy and measured redshift values plus X-ray spectral information, i.e. 2-10 and 20-100 keV fluxes plus column densities. In their paper, the authors mainly use this sample to study the absorption properties of active galaxies, to probe new AGN classes and to test the AGN unification scheme. The authors find that half (48%) of the sample is absorbed, while the fraction of Compton-thick AGN is small (~7%). In line with their previous analysis, they have however shown that when the bias towards heavily absorbed objects which are lost if weak and at large distance is removed, as is possible in the local Universe, the above fractions increase to become 80% and 17%, respectively. The authors also find that absorption is a function of source luminosity, which implies some evolution in the obscuration properties of AGN. A few peculiar classes, so far poorly studied in the hard X-ray band, have been detected and studied for the first time such as 5 X-ray bright optically normal galaxies (XBONGs), 5 type 2 QSOs and 11 low-ionization nuclear emission regions. In terms of optical classification, this sample contains 57% type 1 and 43% type 2 AGN; this subdivision is similar to that found in X-rays if unabsorbed versus absorbed objects are considered, suggesting that the match between optical and X-ray classifications is on the whole good. Only a small percentage of sources (12%) does not fulfill the expectation of the unified theory as the authors find 22 type 1 AGN which are absorbed and 10 type 2 AGN which are unabsorbed. Studying in depth these outliers they found that most of the absorbed type 1 AGN have X-ray spectra characterized by either complex or warm/ionized absorption more likely due to ionized gas located in an accretion disc wind or in the bi-conical structure associated with the central nucleus, therefore unrelated to the toroidal structure. Among the 10 type 2 AGN which are unabsorbed, at most 3-4% are still eligible to be classified as 'true' type 2 AGN.

In the fourth INTEGRAL/IBIS survey (Bird et al. 2010, ApJS, 186, 1, available in the HEASARC database as the IBISCAT4 table), there are 234 objects which have been identified with AGN. To this set of sources, the present authors then added 38 galaxies listed in the INTEGRAL all-sky survey by Krivonos et al. (2007, A&A, 475, 775, available in the HEASARC database as the INTIBISASS table) updated on the website (http://hea.iki.rssi.ru/integral/survey/catalog.php) but not included in the Bird et al. catalog due to the different sky coverage (these latter sources are indicated with hard_flag = 'h' values in this HEASARC table). The final data set presented and discussed in the reference paper and constituting this table therefore comprises 272 AGN and was last updated in March 2011 March. It represents the most complete view of the INTEGRAL extragalactic sky as of the date of publication in 2012.

Catalog Bibcode

2012MNRAS.426.1750M

References

The INTEGRAL/IBIS AGN catalogue.
I. X-ray absorption properties versus optical classification.
    Malizia A., Bassani L., Bazzano A., Bird A.J., Masetti N., Panessa F.,
    Stephen J.B., Ubertini P.
   <Mon. Not. R. Astron. Soc., 426, 1750-1766 (2012)>
   =2012MNRAS.426.1750M

Provenance

This table was created by the HEASARC in October 2014 based on CDS Catalog J/MNRAS/426/1750 files tablea1.dat and refs.dat.

Parameters

Name
A commonly used name for the AGN.

Source_Flag
This flag parameter contains codes which indicate individual notes regarding certain sources, with the following meanings:

     a = Interacting galaxies where the INTEGRAL/IBIS detection is referred to
         both galaxies and the 20-100 keV flux has been estimated to be 50 per
         cent to each galaxy (see the text of the paper for details).
     b = This source has a wrong name (ESO 548-G01) in the fourth IBIS catalog,
         here the right name and the right redshift have been reported.
     c = A different value of column density comes from a published Chandra
         observation (Tomsick et al., 2007, ATel, 1018) where it is not clear
         whether the authors include Galactic absorption or not in their estimate
         of NH. This source has now been observed by XRT and these more recent
         data provide a column density of NH = 0.95 (+0.34, -0.30) x 10²²
         cm^-2; since the Galactic absorption in the source direction is
         ~10²² cm^-2, it is very likely that the Chandra estimate includes
         both Galactic and intrinsic absorption.
     d = INTEGRAL flux comes from the whole map and has to be considered as a
         lower limit since the source has been best detected in a revolution map
         likely during a flare. Its variability and its black hole mass
         (Masetti et al. 2010, A&A, 519, A96) are typical of hard X-ray selected
         blazars; however, the lack of radio detection poses still some doubts
         on the blazar nature.
     e = ESO 138-1 and NGC 6221 are blended in the IBIS maps and through a
         simulation we have estimated the contribution of each source in
         the 20-100keV band which is almost 50 per cent.
     f = For this source the authors have very recently obtained XMM data.
         The preliminary analysis indicates that the column density is
         0.81^+0.05_-0.04_x10¹²cm^-2; this value is compatible with that
         measured by XRT (Molina et al. 2009, MNRAS, 399, 1293) but the
         uncertainty is now sufficiently small to consider the source as not
         absorbed.
     g = Pair of galaxies MCG+04-48-002 (#1) and NGC 6921 (#2) where the
         INTEGRAL/IBIS detection is referred to both galaxies and the 20-100keV
         flux of each has been estimated.

Hard_Flag
This flag parameter is set to 'h' to indicate that the source is one of the hard X-ray sources from the INTEGRAL all-sky survey catalogued by Krivonos et al. (2007, A&A, 475, 775) (see the Overview above and the text of the reference paper).

RA
The Right Ascension of the AGN in the selected equinox. This was given in J2000.0 equatorial coordinates to a precision of 0.01 seconds of time in the original table.

Dec
The Declination of the AGN in the selected equinox. This was given in J2000.0 equatorial coordinates to a precision of 0.1 arcseconds in the original table.

LII
The Galactic Longitude of the AGN

BII
The Galactic Latitude of the AGN.

Redshift
The redshift of the AGN.

Source_Type
The classification of the AGN using the following types: BL Lac, LINER, NLS1, QSO/Blazar, Radio Galaxy, Sy 1, Sy1.2, Sy1.5, Sy1.8. Sy2, and XBONG (X-ray bright optically normal galaxy).

HB_Flux_Limit
This limit parameter indicates if the corresponding flux value is an upper ('<') or lower ('>') limit, else is blank.

HB_Flux
The flux of the AGN in the hard (20 - 100 keV) energy range, in erg s^-1 cm^-2.

SB_Flux_Limit
This limit parameter indicates if the corresponding flux value is an upper ('<') or lower ('>') limit, else is blank.

SB_Flux
The flux of the AGN in the soft (2 - 10 keV) energy range, in erg s^-1 cm^-2.

Var_Flag
This flag parameter is set to 'v' to indicate that the flux is variable. One AGN (Mark 501) has a value of 'vv': the HEASARC is uncertain what this latter value represents (very variable, perhaps). In the original table, the character(s) '*' and '**' were used for these non-blank flag values.

Log_NH_Limit
This limit parameter indicates if the corresponding parameter value is an upper ('<') or lower ('>') limit, else is blank.

Log_NH
The logarithm of the measured column density towards the AGN, in units of H atoms cm^-2, except if log_nh_flag = 'g', when the value adopted is the Galactic column density in the source direction, or if log_nh_flag = 'f', when a fixed value has been adopted (see the text for more details).

Log_NH_Flag
This flag parameter is set to = 'g', when the value adopted is the Galactic column density in the source direction, or to 'f', when a fixed value has been adopted, else is left blank.

Log_NH_Lower
The lower bound to the logarithm of the measured column density towards the AGN, in units of H atoms cm^-2.

Log_NH_Upper
The upper bound to the logarithm of the measured column density towards the AGN, in units of H atoms cm^-2.

Ref_Bibcode
The bibliographic code ('bibcode') of the reference from which the quoted information was taken.

Ref_Authors
The authors of the reference from which the quoted information was taken.

Ref_Comments
Some identifying comments regarding the reference source in those cases lacking a bibcode.

Class
The HEASARC Browse object classification, based on the value of the source_type parameter.

Contact Person

Questions regarding the INTIBISAGN database table can be addressed to the HEASARC Help Desk.

Page Author: Browse Software Development Team
Last Modified: Monday, 16-Sep-2024 17:29:14 EDT