A Census of Mid-Infrared Selected Active Galactic Nuclei in Massive Galaxy Clusters at 0 < z < 1.3
| dc.contributor | Tran, Kim-Vy | |
| dc.creator | Tomczak, Adam 1987- | |
| dc.date.accessioned | 2013-03-14T16:22:39Z | |
| dc.date.accessioned | 2017-04-07T20:03:25Z | |
| dc.date.available | 2013-03-14T16:22:39Z | |
| dc.date.available | 2017-04-07T20:03:25Z | |
| dc.date.created | 2012-12 | |
| dc.date.issued | 2012-10-29 | |
| dc.description.abstract | We conduct a deep mid-infrared census of nine massive galaxy clusters at (0 < z < 1.3) with a total of ~ 1500 spectroscopically confirmed member galaxies using Spitzer /IRAC photometry and established mid-infrared color selection techniques. Of the 949 cluster galaxies that are detected in at least three of the four IRAC channels at the >= 3 sigma level, we identify 12 that host mid-infrared selected active galactic nuclei (IR-AGN). To compare the IR-AGN across our redshift range, we define two complete samples of cluster galaxies: (1) optically-selected members with rest-frame VAB magnitude < -21.5 and (2) mid-IR selected members brighter than (M*_3.6 +0.5), i.e. essentially a stellar mass cut. In both samples, we measure f_IR-AGN ~ 1% with a strong upper limit of ~3% at z < 1. This uniformly low IR-AGN fraction at z < 1 is surprising given the fraction of 24 micrometer sources in the same galaxy clusters is observed to increase by about a factor of four from z ~ 0 to z ~ 1; this indicates that most of the detected 24 micrometer flux is due to star formation. Only in our single galaxy cluster at z = 1.24 is the IR-AGN fraction measurably higher at ~15% (all members; ~70% for late-types only). In agreement with recent studies, we find the cluster IR-AGN are predominantly hosted by late-type galaxies with blue optical colors, i.e. members with recent/ongoing star formation. The four brightest IR-AGN are also X-ray sources; these IR+X-ray AGN all lie outside the cluster core (R_proj > 0.5 Mpc) and are hosted by highly morphologically disturbed members. Although our sample is limited, our results suggest that f_IR-AGN in massive galaxy clusters is not strongly correlated with star formation at z < 1, and that IR-AGN have a more prominent role at z > 1. | |
| dc.identifier.uri | http://hdl.handle.net/1969.1/148357 | |
| dc.subject | infrared galaxies | |
| dc.subject | galaxy evolution | |
| dc.subject | clusters | |
| dc.subject | active galaxies | |
| dc.subject | galaxies | |
| dc.title | A Census of Mid-Infrared Selected Active Galactic Nuclei in Massive Galaxy Clusters at 0 < z < 1.3 | |
| dc.type | Thesis |