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.
@article{arxiv.0909.5345,
title = {Accurate classification of 17 AGNs detected with Swift/BAT},
author = {P. Parisi and N. Masetti and E. Jiménez-Bailón and V. Chavushyan and A. Malizia and R. Landi and M. Molina and M. Fiocchi and E. Palazzi and L. Bassani and A. Bazzano and A. J. Bird and A. J. Dean and G. Galaz and E. Mason and D. Minniti and L. Morelli and J. B. Stephen and P. Ubertini},
journal= {arXiv preprint arXiv:0909.5345},
year = {2015}
}
Comments
15 pages, 7 figures, 4 tables. Accepted for publication on Astronomy & Astrophysics, main journal. The name of the source Swift J0519.5-3140 corrected with Swift J0501.9-3239