2016/04/18 by F. La Franca, Fabio La Franca, Francesca Onori +11
Physics and Astronomy · #Active galactic nucleus #Astronomy #Astrophysical Phenomena and Observations #Astrophysics #Galaxies: Formation, Evolution, Phenomena #Galaxy #Gamma-ray bursts and supernovae #Luminosity #Luminous infrared galaxy #Physics #Virial mass #Virial theorem #astro-ph.GA
paper · pdf · doi:10.3389/fspas.2016.00012
published as Front. Astron. Space Sci. 3:12 (2016) · 13 pages, 3 figures, 1 table. Published in Frontiers in Astronomy and Space Sciences
openalex publication_date 2016/04/18 · arxiv created 2016/05/20 · arxiv updated 2016/05/23 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/05
In the last decade, using single epoch virial based techniques in the optical band, it has been possible to measure the central black hole mass on large type 1 Active Galactive Nuclei (AGN) samples. However these measurements use the width of the broad line region as a proxy of the virial velocities and are therefore difficult to be carried out on those obscured (type 2) or low luminosity AGN where the nuclear component does not dominate in the optical. Here we present the optical and near infrared spectrum of the starburst/Seyfert galaxy NGC 6221, observed with X-shooter/VLT. Previous observations of NGC 6221 in the X-ray band shows an absorbed (NH=8.5 +/- 0.4 x 1021 cm-2) spectrum typical of a type 2 AGN with luminosity log(L14-195/ erg s-1) = 42.05, while in the optical band its spectrum is typical of a reddened (AV=3) starburst. Our deep X-shooter/VLT observations have allowed us to detect faint broad emission in the Halpha, HeI and Pabeta lines (FWHM=1400-2300 km s-1) confirming previous studies indicating that NGC 6221 is a reddened starbust galaxy which hosts an AGN. We use the measure of the broad components to provide a first estimate of its central black hole mass (MBH = 106.6+/-0.3 Msol, lambdaEdd=0.01-0.03), obtained using recently calibrated virial relations suitable for moderately obscured (NH<1024 cm-2) AGN.