Type 2 AGN host galaxies in the Chandra-COSMOS Legacy Survey: No Evidence of AGN-driven Quenching

Hyewon Suh, Francesca Civano, Guenther Hasinger, Elisabeta Lusso, Giorgio Lanzuisi, Stefano Marchesi, Benny Trakhtenbrot, Viola Allevato, Nico Cappelluti, Peter L. Capak, Martin Elvis, Richard E. Griffiths, Clotilde Laigle, Paulina Lira, Laurie Riguccini, David J. Rosario, Mara Salvato, Kevin Schawinski, Cristian Vignali

Published 2017-05-10Version 1

We investigate the star formation properties of a large sample of ~2300 X-ray-selected Type 2 Active Galactic Nuclei (AGNs) host galaxies out to z~3 in the Chandra COSMOS Legacy Survey in order to understand the connection between the star formation and nuclear activity. Making use of the existing multi-wavelength photometric data available in the COSMOS field, we perform a multi-component modeling from far-infrared to near-ultraviolet using a nuclear dust torus model, a stellar population model and a starburst model of the spectral energy distributions (SEDs). Through detailed analysis of SEDs, we derive the stellar masses and the star formation rates (SFRs) of Type 2 AGN host galaxies. The stellar mass of our sample is in the range 9 < log M_{stellar}/M_{\odot} < 12 with uncertainties of ~0.19 dex. We find that Type 2 AGN host galaxies have, on average, similar SFRs compared to the normal star-forming galaxies with similar M_{stellar} and redshift ranges, suggesting no significant evidence for enhancement or quenching of star formation. This could be interpreted in a scenario, where the relative massive galaxies have already experienced substantial growth at higher redshift (z>3), and grow slowly through secular fueling processes hosting moderate-luminosity AGNs.