Accurate classification of 17 AGNs detected with Swift/BAT

TL;DR

This study used optical spectroscopy and X-ray data to classify 17 AGNs detected by Swift/BAT, revealing their types, redshifts, and absorption properties, and identifying highly absorbed and naked Seyfert 2 galaxies.

Contribution

It provides a detailed optical and X-ray classification of 17 hard X-ray selected AGNs, improving understanding of their nature and absorption characteristics.

Findings

7 are Type 1 AGNs

9 are Type 2 AGNs

1 is an X-ray bright optically normal galaxy

Abstract

Through an optical campaign performed at 5 telescopes located in the northern and the southern hemispheres, plus archival data from two on line sky surveys, we have obtained optical spectroscopy for 17 counterparts of suspected or poorly studied hard X-ray emitting active galactic nuclei (AGNs) detected with Swift/BAT in order to determine or better classify their nature. We find that 7 sources of our sample are Type 1 AGNs, 9 are Type 2 AGNs, and 1 object is an X-ray bright optically normal galaxy; the redshifts of these objects lie in a range between 0.012 and 0.286. For all these sources, X-ray data analysis was also performed to estimate their absorption column and to search for possible Compton thick candidates. Among our type 2 objects, we did not find any clear Compton thick AGN, but at least 6 out of 9 of them are highly absorbed (N_H > 10^23 cm^-2), while one does not require intrinsic absorption; i.e., it appears to be a naked Seyfert 2 galaxy.