Deep Herschel view of obscured star formation in the Bullet cluster
Smail, I.; Kneib, J. -P.; Smith, G. P.; Lutz, D.; Altieri, B.; Rodighiero, G.; Valtchanov, I.; Ivison, R. J.; Ilbert, O.; Schaerer, D.; Bock, J. J.; Pelló, R.; Dessauges-Zavadsky, M.; Egami, E.; Appleton, P. N.; van der Werf, P.; Dowell, C. D.; Zemcov, M.; Richard, J.; Rieke, G. H.; Rex, M.; Walth, G. L.; Combes, F.; Bridge, C. R.; Gonzalez, A. H.; Blain, A. W.; Pérez-González, P. G.; Rawle, T. D.; Boone, F.; Werner, M. W.; Jauzac, M.; Fadda, D.; Chung, S. M.; Pereira, M. J.; Clement, B.; Fiedler, A. K.
United States, Spain, United Kingdom, France, Switzerland, Germany, Italy, Netherlands
Abstract
We use deep, five band (100-500 μm) data from the Herschel Lensing Survey (HLS) to fully constrain the obscured star formation rate, SFRFIR, of galaxies in the Bullet cluster (z = 0.296), and a smaller background system (z = 0.35) in the same field. Herschel detects 23 Bullet cluster members with a total SFRFIR = 144±14 M⊙ yr-1. On average, the background system contains brighter far-infrared (FIR) galaxies, with ~50% higher SFRFIR (21 galaxies; 207± 9 M⊙ yr-1). SFRs extrapolated from 24 μm flux via recent templates (SFR24 µm) agree well with SFRFIR for ~60% of the cluster galaxies. In the remaining ~40%, SFR24 µm underestimates SFRFIR due to a significant excess in observed S100/S24 (rest frame S75/S18) compared to templates of the same FIR luminosity.
Herschel is an ESA space observatory with science instruments provided by European-led Principal Investigator consortia and with important participation from NASA. Data presented in this paper were analyzed using “The Herschel Interactive Processing Environment (HIPE)”, a joint development by the Herschel Science Ground Segment Consortium, consisting of ESA, the NASA Herschel Science Center, and the HIFI, PACS and SPIRE consortia.