{ "id": "1011.6370", "version": "v2", "published": "2010-11-29T21:00:01.000Z", "updated": "2011-01-18T17:20:49.000Z", "title": "The star formation history of mass-selected galaxies in the COSMOS field", "authors": [ "Alexander Karim", "Eva Schinnerer", "Alejo Martinez-Sansigre", "Mark T. Sargent", "Arjen van der Wel", "Hans-Walter Rix", "Olivier Ilbert", "Vernesa Smolcic", "Chris Carilli", "Maurilio Pannella", "Anton M. Koekemoer", "Eric F. Bell", "Mara Salvato" ], "comment": "37 pages, 14 figures, 7 tables; accepted for publication in the Astrophysical Journal; High resolution versions of all figures available at www.mpia-hd.mpg.de/homes/karim/research.html", "doi": "10.1088/0004-637X/730/2/61", "categories": [ "astro-ph.CO" ], "abstract": "We explore the evolution of the specific star formation rate (SSFR) for 3.6um-selected galaxies of different M_* in the COSMOS field. The average SFR for sub-sets of these galaxies is estimated with stacked 1.4GHz radio continuum emission. We separately consider the total sample and a subset of galaxies (SF) that shows evidence for substantive recent star formation in the rest-frame optical SED. At 0.22, at least above 4x10^10M_Sun where our conclusions are most robust. We find a tight correlation with power-law dependence, SSFR (M_*)^beta, between SSFR and M_* at all z. It tends to flatten below ~10^10M_Sun if quiescent galaxies are included; if they are excluded a shallow index beta_SFG -0.4 fits the correlation. On average, higher M_* objects always have lower SSFRs, also among SF galaxies. At z>1.5 there is tentative evidence for an upper SSFR-limit that an average galaxy cannot exceed. It is suggested by a flattening of the SSFR-M_* relation (also for SF sources), but affects massive (>10^10M_Sun) galaxies only at the highest z. Below z=1.5 there thus is no direct evidence that galaxies of higher M_* experience a more rapid waning of their SSFR than lower M_* SF systems. In this sense, the data rule out any strong 'downsizing'. We combine our results with recent measurements of the galaxy (stellar) mass function in order to determine the characteristic mass of a SF galaxy (M_*=10^(10.6\\pm0.4)M_Sun). In this sense, too, there is no 'downsizing'. Our analysis constitutes the most extensive SFR density determination with a single technique to z=3. Recent Herschel results are consistent with our results, but rely on far smaller samples.", "revisions": [ { "version": "v2", "updated": "2011-01-18T17:20:49.000Z" } ], "analyses": { "keywords": [ "star formation history", "cosmos field", "mass-selected galaxies", "4ghz radio continuum emission", "specific star formation rate" ], "tags": [ "journal article" ], "publication": { "journal": "The Astrophysical Journal", "year": 2011, "month": "Apr", "volume": 730, "number": 2, "pages": 61 }, "note": { "typesetting": "TeX", "pages": 37, "language": "en", "license": "arXiv", "status": "editable", "inspire": 878625, "adsabs": "2011ApJ...730...61K" } } }