Volume 639, July 2020
|Number of page(s)
|01 July 2020
X-ray absorption in INTEGRAL active galactic nuclei
Host galaxy inclination⋆
Osservatorio di Astrofisica Spaziale e Scienza dello Spazio – INAF, Via P. Gobetti 101, 40129 Bologna, Italy
2 Istituto di Astrofisica e Planetologia Spaziali – INAF, Via Fosso del Cavaliere 100, 00133 Roma, Italy
Accepted: 29 April 2020
In this work the INTEGRAL hard X-ray selected sample of active galactic nuclei (AGN) has been used to investigate the possible contribution of absorbing material distributed within the host galaxies to the total amount of NH measured in the X-ray band. We collected all the available axial ratio measurements of the galaxies hosting our AGN together with their morphological information and found that for our hard X-ray selected sample as well there is a deficit of edge-on galaxies hosting type 1 AGN. We estimate that in our hard X-ray selected sample there is a deficit of 24% (±5%) of type 1 AGN. Possible bias in redshift has been excluded, as we found the same effect in a well-determined range of z where the number and the distributions of the two classes are statistically the same. Our findings clearly indicate that material located in the host galaxy on scales of hundreds of parsecs and not aligned with the putative absorbing torus of the AGN can contribute to the total amount of column density. This galactic absorber could be large enough to hide the broad line region of some type 1 AGN, thus causing their classification as type 2 objects and giving rise to the deficiency of type 1 objects in edge-on galaxies.
Key words: X-rays: galaxies / galaxies: active / galaxies: Seyfert
Tables A1–A3 are only available at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (18.104.22.168) or via http://cdsarc.u-strasbg.fr/viz-bin/cat/J/A+A/639/A5
© ESO 2020
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