2007/12/19 by A. Alonso-Herrero, A. Alonso‐Herrero, P. G. Perez-Gonzalez +10 · 1 citation
Physics and Astronomy · #Active galactic nucleus #Astronomy #Astronomy and Astrophysical Research #Astrophysical Phenomena and Observations #Astrophysics #Chandra Deep Field South #Galaxies: Formation, Evolution, Phenomena #Galaxy #Luminous infrared galaxy #Physics #Population #Quasar #Redshift #Star formation #Stellar mass #Supermassive black hole #astro-ph
paper · pdf · doi:10.1086/529010
Accepted for Publication in ApJ
arxiv created 2007/12/19 · openalex publication_date 2008/04/04 · arxiv updated 2009/12/01 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/05
We study the stellar and star formation properties of the host galaxies of 58 X-ray-selected AGNs in the GOODS portion of the Chandra Deep Field South (CDF-S) region at z ∼ 0.5-1.4. The AGNs are selected such that their rest-frame UV to near-infrared spectral energy distributions (SEDs) are dominated by stellar emission; i.e., they show a prominent 1.6 μm bump, thus minimizing the AGN emission "contamination." This AGN population comprises approximately 50% of the X-ray-selected AGNs at these redshifts. We find that AGNs reside in the most massive galaxies at the redshifts probed here. Their characteristic stellar masses ( M * ∼ 7.8 × 10 10 and M * ∼ 1.2 × 10 11 M ☉ at median redshifts of 0.67 and 1.07, respectively) appear to be representative of the X-ray-selected AGN population at these redshifts and are intermediate between those of local type 2 AGNs and high-redshift ( z ∼ 2) AGNs. The inferred black hole masses ( M BH ∼ 2 × 10 8 M ☉ ) of typical AGNs are similar to those of optically identified quasars at similar redshifts. Since the AGNs in our sample are much less luminous ( L 2–10 keV < 10 44 erg s −1 ) than quasars, typical AGNs have low Eddington ratios (η ∼ 0.01-0.001). This suggests that, at least at intermediate redshifts, the cosmic AGN "downsizing" is due to both a decrease in the characteristic stellar mass of typical host galaxies and less efficient accretion. Finally, there is no strong evidence in AGN host galaxies for either highly suppressed star formation (expected if AGNs played a role in quenching star formation) or elevated star formation when compared to mass-selected (i.e., IRAC-selected) galaxies of similar stellar masses and redshifts.