SPT-CL J2040-4451: An SZ-selected Galaxy Cluster at z = 1.478 with Significant Ongoing Star Formation
Abstract
SPT-CL J2040-4451—spectroscopically confirmed at z = 1.478—is the highest-redshift galaxy cluster yet discovered via the Sunyaev-Zel'dovich effect. SPT-CL J2040-4451 was a candidate galaxy cluster identified in the first 720 deg2 of the South Pole Telescope Sunyaev-Zel'dovich (SPT-SZ) survey, and has been confirmed in follow-up imaging and spectroscopy. From multi-object spectroscopy with Magellan-I/Baade+IMACS we measure spectroscopic redshifts for 15 cluster member galaxies, all of which have strong [O II] λλ3727 emission. SPT-CL J2040-4451 has an SZ-measured mass of M 500, SZ = 3.2 ± 0.8 × 1014 M ⊙ h 70-1, corresponding to M 200, SZ = 5.8 ± 1.4 × 1014 M ⊙ h 70-1. The velocity dispersion measured entirely from blue star-forming members is σ v = 1500 ± 520 km s-1. The prevalence of star-forming cluster members (galaxies with >1.5 M ⊙ yr-1) implies that this massive, high-redshift cluster is experiencing a phase of active star formation, and supports recent results showing a marked increase in star formation occurring in galaxy clusters at z >~ 1.4. We also compute the probability of finding a cluster as rare as this in the SPT-SZ survey to be >99%, indicating that its discovery is not in tension with the concordance ΛCDM cosmological model.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- October 2014
- DOI:
- 10.1088/0004-637X/794/1/12
- arXiv:
- arXiv:1307.2903
- Bibcode:
- 2014ApJ...794...12B
- Keywords:
-
- galaxies: clusters: individual: SPT-CL J2040–4451;
- galaxies: distances and redshifts;
- galaxies: evolution;
- large-scale structure of universe;
- Astrophysics - Cosmology and Nongalactic Astrophysics
- E-Print:
- 14 pages, 8 figures, 4 tables, Accepted to ApJ