Herschel and ALMA Observations of Massive SZE-selected Clusters
Abstract
We present new Herschel observations of four massive, Sunyaev-Zel’dovich effect-selected clusters at 0.3≤slant z≤slant 1.1, two of which have also been observed with the Atacama Large Millimeter/submillimeter Array (ALMA). We detect 19 Herschel/Photoconductor Array Camera and Spectrometer (PACS) counterparts to spectroscopically confirmed cluster members, five of which have redshifts determined via CO (4-3) and [C I] ({}3{P}1{--}{}3{P}0) lines. The mean [C I]/CO line ratio is 0.19 ± 0.07 in brightness temperature units, consistent with previous results for field samples. We do not detect significant stacked ALMA dust continuum or spectral-line emission, implying upper limits on mean interstellar medium (H2 + H I) and molecular gas masses. An apparent anticorrelation of {L}{IR} with clustercentric radius is driven by the tight relation between star formation rate and stellar mass. We find an average specific star formation rate of log(sSFR/yr-1) = -10.36, which is below the {SFR}{--}{M}* correlation measured for field galaxies at similar redshifts. The fraction of infrared-bright galaxies (IRBGs; {log}({L}{IR}/{L}⊙ )> 10.6) per cluster and average sSFR rise significantly with redshift. For CO detections, we find {f}{gas}∼ 0.2, comparable to those of field galaxies, and gas depletion timescales of about 2 Gyr. We use radio observations to distinguish active galactic nuclei (AGNs) from star-forming galaxies. At least four of our 19 Herschel cluster members have {q}{IR}< 1.8, implying an AGN fraction {f}{AGN}≳ 0.2 for our PACS-selected sample.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- February 2018
- DOI:
- 10.3847/1538-4357/aaa0dc
- arXiv:
- arXiv:1712.04540
- Bibcode:
- 2018ApJ...853..195W
- Keywords:
-
- galaxies: clusters: general;
- galaxies: evolution;
- galaxies: ISM;
- Astrophysics - Astrophysics of Galaxies
- E-Print:
- Accepted in ApJ, 46 pages, 13 figures