Black hole accretion and host galaxies of obscured quasars in XMM-COSMOS

Autor: Mainieri, V., Bongiorno, A., Merloni, A., Aller, M., Carollo, M., Iwasawa, K., Koekemoer, A. M., Mignoli, M., Silverman, J. D., Bolzonella, M., Brusa, M., Comastri, A., Gilli, R., Halliday, C., Ilbert, O., Lusso, E., Salvato, M., Vignali, C., Zamorani, G., Contini, T., Kneib, J. -P., Fevre, O. Le, Lilly, S., Renzini, A., Scodeggio, M., Balestra, I., Bardelli, S., Caputi, K., Coppa, G., Cucciati, O., de la Torre, S., de Ravel, L., Franzetti, P., Garilli, B., Iovino, A., Kampczyk, P., Knobel, C., Kovac, K., Lamareille, F., Borgne, J. -F. Le, Brun, V . Le, Maier, C., Nair, P., Pello, R., Peng, Y., Montero, E. Perez, Pozzetti, L., Ricciardelli, E., Tanaka, M., Tasca, L., Tresse, L., Vergani, D., Zucca, E., Aussel, H., Capak, P., Cappelluti, N., Elvis, M., Fiore, F., Hasinger, G., Impey, C., Floc'h, E. Le, Scoville, N., Taniguchi, Y., Trump, J.
Rok vydání: 2011
Předmět:
Druh dokumentu: Working Paper
DOI: 10.1051/0004-6361/201117259
Popis: We explore the connection between black hole growth at the center of obscured quasars selected from the XMM-COSMOS survey and the physical properties of their host galaxies. We study a bolometric regime ( 8 x 10^45 erg/s) where several theoretical models invoke major galaxy mergers as the main fueling channel for black hole accretion. We confirm that obscured quasars mainly reside in massive galaxies (Mstar>10^10 Msun) and that the fraction of galaxies hosting such powerful quasars monotonically increases with the stellar mass. We stress the limitation of the use of rest-frame color-magnitude diagrams as a diagnostic tool for studying galaxy evolution and inferring the influence that AGN activity can have on such a process. We instead use the correlation between star-formation rate and stellar mass found for star-forming galaxies to discuss the physical properties of the hosts. We find that at z ~1, ~62% of Type-2 QSOs hosts are actively forming stars and that their rates are comparable to those measured for normal star-forming galaxies. The fraction of star-forming hosts increases with redshift: ~71% at z ~2, and 100% at z ~3. We also find that the the evolution from z ~1 to z ~3 of the specific star-formation rate of the Type-2 QSO hosts is in excellent agreement with that measured for star-forming galaxies. From the morphological analysis, we conclude that most of the objects are bulge-dominated galaxies, and that only a few of them exhibit signs of recent mergers or disks. Finally, bulge-dominated galaxies tend to host Type-2 QSOs with low Eddington ratios (lambda<0.1), while disk-dominated or merging galaxies have at their centers BHs accreting at high Eddington ratios (lambda > 0.1).
Comment: Accepted by A&A. 20 pages, 16 figures, 2 tables. A version with higher resolution figures and SED fits of Appendix A is available at http://www.eso.org/~vmainier/QSO2/qso2.pdf
Databáze: arXiv
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