Accurate classification of 17 AGNs detected with Swift/BAT*
1
INAF – Istituto di Astrofisica Spaziale e Fisica Cosmica di Bologna, via Gobetti 101, 40129 Bologna, Italy e-mail: parisi@iasfbo.inaf.it
2
Dipartimento di Astronomia, Università di Bologna, via Ranzani 1, 40129 Bologna, Italy
3
Instituto de Astronomía, Universidad Nacional Autónoma de Mexico, Apartado Postal 70-264, 04510 Mexico D.F., Mexico
4
Instituto Nacional de Astrofísica, Óptica y Electrónica, Apartado Postal 51-216, 72000 Puebla, Mexico
5
INAF – Istituto di Astrofisica Spaziale e Fisica Cosmica di Milano, via Bassini 15, 20122 Milan, Italy
6
Istituto di Astrosica Spaziale e Fisica Cosmica di Roma (INAF), via Fosso del Cavaliere 100, Roma 00133, Italy
7
School of Physics & Astronomy, University of Southampton, Southampton, Hampshire, SO171BJ, UK
8
Departamento de Astronomía y Astrofísica, Pontificia Universidad Católica de Chile, Casilla 306, Santiago 22, Chile
9
European Southern Observatory, Alonso de Cordova 3107, Vitacura, Santiago, Chile
10
Specola Vaticana, 00120 Città del Vaticano, Italy
11
Dipartimento di Astronomia, Università di Padova, Vicolo dell'Osservatorio 3, 35122 Padua, Italy
Received:
20
July
2009
Accepted:
12
September
2009
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 (NH > 1023 cm-2), while one does not require intrinsic absorption; i.e., it appears to be a naked Seyfert 2 galaxy.
Key words: galaxies: Seyfert / techniques: spectroscopic
Based on observations obtained from the following observatories: Telescopio Nazionale Galileo at the Observatorio del Roque de los Muchachos of the Instituto de Astrofísica de Canarias (Canary Islands, Spain); Astronomical Observatory of Bologna in Loiano (Italy); Astronomical Observatory of Asiago (Italy); Cerro Tololo Interamerican Observatory (Chile); Observatorio Astronómico Nacional (San Pedro Mártir, Mexico).
© ESO, 2009