Cowley et al. 2015 Summary: We investigate AGN candidates within the FourStar Galaxy Evolution (ZFOURGE) Survey to determine the impact they have on star formation in their host galaxies. By cross- matching the deep Ks-band imaging of ZFOURGE with overlapping multi wavelength data, we identify a population of radio, X-ray, and infrared-selected AGN over z = 0.2–3.2.
Using 160 μm Herschel PACS data, we compare the specific star formation rates (sSFRs) of the AGN hosts to a mass-matched control sample of inactive galaxies and find AGN to be elevated by 0.34 ± 0.07 dex across all redshifts. We discuss scenarios that may explain these findings and postulate that AGN are less likely to be a dominant mechanism for moderating galaxy growth via quenching than has previously been suggested.
Infrared (top), X-ray (bottom-left) and radio (bottom-right) AGN hosts identified in ZFOURGE. These sources are flagged to generate a complementary catalogue to the primary ZFOURGE catalogues and will be made available at http://zfourge.tamu.edu upon the full public release of ZFOURGE.
The mean star-formation activity (sSFR) of our AGN hosts (closed markers) and inactive galaxies (open markers) split by AGN class (IR, X-ray and radio). With the exception of low-redshift radio AGN, all AGN hosts show an elevated level of star formation activity, at all redshifts, with respect to their control sample of inactive galaxies.