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Paper: Color-Magnitude Relations of Active and Non-Active Galaxies in the Chandra Deep Fields: Stellar-Mass Selection Effects and High-Redshift Constraints
Volume: 439, The Galactic Center: a Window to the Nuclear Environment of Disk Galaxies
Page: 478
Authors: Xue, Y. Q.; Brandt, W. N.; Luo, B.; Rafferty, D. A.; Alexander, D. M.; Bauer, F. E.; Lehmer, B. D.; Silverman, J. D.
Abstract: We extend color-magnitude relations of X-ray AGN hosts and non-AGN galaxies up to z ≈ 3 in the 2 Ms Chandra Deep Field-North and South (CDF-N and CDF-S; jointly CDFs) surveys. Our stellar-mass selected (M* ≥ 109.0M) sample consists of 198 X-ray selected moderate-luminosity (41.9≤ log(L0.5–8keV) ≤ 43.7) AGNs and their parent sample of 8122 galaxies with 0 < z ≤ 3 and mR ≤ 26, which are located in the most sensitive central areas of the 2 Ms CDFs. We utilized analyses of color-magnitude diagrams to assess the role of AGNs in galaxy evolution. First, we confirm some previous results and extend them to higher redshifts, e.g., most AGNs reside in massive galaxies, up to z ≈ 3. Second, we point out that, in order to obtain a complete and reliable picture, it is critical to use mass-matched samples to examine color-magnitude relations of AGN hosts and non-AGN galaxies, because results change when considering a mass-matched sample versus a mass-unmatched sample. With mass-selection effects taken into account, we find that our main results can be reasonably explained by the color-mass correlation (i.e., X-ray AGNs preferentially reside in massive galaxies that tend to be redder). Consequently, AGN feedback does not appear necessary to explain our main results in this work.
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