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|Title:||The Herschel view of the dominant mode of galaxy growth from z = 4 to the present day||Authors:||Schreiber, C.
Sargent, M. T.
Faber, S. M.
Ferguson, H. C.
Koekemoer, A. M.
Morrison, G. E.
|Issue Date:||2015||Journal:||ASTRONOMY & ASTROPHYSICS||Number:||575||Abstract:||We present an analysis of the deepest Herschel images in four major extragalactic fields GOODS-North, GOODS-South, UDS, and COSMOS obtained within the GOODS-Herschel and CANDELS-Herschel key programs. The star formation picture provided by a total of 10 497 individual far-infrared detections is supplemented by the stacking analysis of a mass complete sample of 62 361 star-forming galaxies from the Hubble Space Telescope (HST) H band-selected catalogs of the CANDELS survey and from two deep ground-based K<SUB>s</SUB> band-selected catalogs in the GOODS-North and the COSMOS-wide field to obtain one of the most accurate and unbiased understanding to date of the stellar mass growth over the cosmic history. We show, for the first time, that stacking also provides a powerful tool to determine the dispersion of a physical correlation and describe our method called "scatter stacking", which may be easily generalized to other experiments. The combination of direct UV and far-infrared UV-reprocessed light provides a complete census on the star formation rates (SFRs), allowing us to demonstrate that galaxies at z = 4 to 0 of all stellar masses (M<SUB>∗</SUB>) follow a universal scaling law, the so-called main sequence of star-forming galaxies. We find a universal close-to-linear slope of the log <SUB>10</SUB>(SFR)-log <SUB>10</SUB>(M<SUB>∗</SUB>) relation, with evidence for a flattening of the main sequence at high masses (log <SUB>10</SUB>(M<SUB>∗</SUB>/M<SUB>☉</SUB>) > 10.5) that becomesless prominent with increasing redshift and almost vanishes by z ≃ 2. This flattening may be due to the parallel stellar growth of quiescent bulges in star-forming galaxies, which mostly happens over the same redshift range. Within the main sequence, we measure a nonvarying SFR dispersion of 0.3 dex: at a fixed redshift and stellar mass, about 68% of star-forming galaxies form stars at a universal rate within a factor 2. The specific SFR (sSFR = SFR/M<SUB>∗</SUB>) of star-forming galaxies is found to continuously increase from z = 0 to 4. Finally we discuss the implications of our findings on the cosmic SFR history and on the origin of present-day stars: more than two-thirds of present-day stars must have formed in a regime dominated by the "main sequence" mode. As a consequence we conclude that, although omnipresent in the distant Universe, galaxy mergers had little impact in shaping the global star formation history over the last 12.5 billion years. <P />Herschel is an ESA space observatory with science instruments provided by European-led Principal Investigator consortia and with important participation from NASA.Appendices are available in electronic form at <A href="http://www.aanda.org/10.1051/0004-6361/201425017/olm">http://www.aanda.org||Acknowledgments:||The authors want to thank the anonymous referee for his/her comments that clearly improved the consistency and overall quality of this paper. C.S. and D.E. are grateful to F. Bournaud for the enlightening discussions that motivated certain aspects of this paper. S.J. acknowledges support from the EU through grant ERC-StG-257720. Most of the numerical analysis conducted in this work have been performed using phy++, a free and open source C++ library for fast and robust numerical astrophysics ( http://cschreib.github.io/phypp/ ). This work is based on observations taken by the CANDELS Multi-Cycle Treasury Program with the NASA/ESA HST, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS5-26555. This research was supported by the French Agence Nationale de la Recherche (ANR) project ANR-09-BLAN-0224 and by the European Commission through the FP7 SPACE project ASTRODEEP (Ref. No. 312725).||URI:||http://hdl.handle.net/20.500.12386/26199||URL:||https://www.aanda.org/articles/aa/abs/2015/03/aa25017-14/aa25017-14.html
|Appears in Collections:||1.01 Articoli in rivista|
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checked on Sep 26, 2020
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