The evolving star formation rate: M-star relation and sSFR since z similar or equal to 5 from the VUDS spectroscopic survey

L. A. M. Tasca (1) , O. Le Fevre (1) , N. P. Hathi (1) , D. Schaerer (2) , O. Ilbert (1) , G. Zamorani (3) , B. C. Lemaux (1) , P. Cassata (1) , B. Garilli , V. Le Brun (1) , D. Maccagni , L. Pentericci (4) , R. Thomas (1) , E. Vanzella (3) , E. Zucca (5) , R. Amorín (4) , S. Bardelli (6) , L. P. Cassara , M. Castellano (4) , Alessandro Cimatti (7) , O. Cucciati (6) , A. Durkalec (1) , A. Fontana (4) , M. Giavalisco (8) , A. Grazian (4) , S. Paltani (9) , B. Ribeiro (1) , M. Scodeggio (10) , V. Sommariva (4) , M. Talia (7, 6) , L. Tresse (1) , D. Vergani (11) , P. Capak (12) , S. Charlot (13) , T. Contini (2) , S. de La Torre (1) , J. Dunlop (14) , S. Fotopoulou (15) , A. Koekemoer (16) , C. Lopez-Sanjuan (1) , Y. Mellier (13) , J. Pforr (17) , M. Salvato (18, 19) , N. Scoville (20) , Y. Taniguchi , P. W. Wang (1)

1 LAM - Laboratoire d'Astrophysique de Marseille
2 IRAP - Institut de recherche en astrophysique et planétologie
3 INAF - Istituto Nazionale di Astrofisica
4 OAR - INAF - Osservatorio Astronomico di Roma
5 Oncology Institute of Southern Switzerland
6 OABO - INAF - Osservatorio Astronomico di Bologna
7 UNIBO - Alma Mater Studiorum Università di Bologna = University of Bologna
8 Department of Astronomy [Amherst]
9 ISDC Data Centre for Astrophysics
10 INAF- Milano
11 OAA - INAF - Osservatorio Astrofisico di Arcetri
12 MPIA - Max-Planck-Institut für Astronomie
13 IAP - Institut d'Astrophysique de Paris
14 SUPA, Institute for Astronomy
15 Aristotle University of Thessaloniki
16 STSci - Space Telescope Science Institute
17 Institute of cosmology and gravitation
18 MPE - Max-Planck-Institut für Extraterrestrische Physik
19 Excellence Cluster Universe
20 CALTECH - California Institute of Technology

We study the evolution of the star formation rate (SFR) - stellar mass (M-star) relation and specific star formation rate (sSFR) of star-forming galaxies (SFGs) since a redshift z similar or equal to 5.5 using 2435 (4531) galaxies with highly reliable spectroscopic redshifts in the VIMOS Ultra-Deep Survey (VUDS). It is the first time that these relations can be followed over such a large redshift range from a single homogeneously selected sample of galaxies with spectroscopic redshifts. The log(SFR) - log(M-star) relation for SFGs remains roughly linear all the way up to z = 5, but the SFR steadily increases at fixed mass with increasing redshift. We find that for stellar masses M-star \textgreater= 3.2 x 10(9) M-circle dot the SFR increases by a factor of similar to 13 between z = 0.4 and z = 2.3. We extend this relation up to z = 5, finding an additional increase in SFR by a factor of 1.7 from z = 2.3 to z = 4.8 for masses M-star = 1010 M-circle dot. We observe a turn-off in the SFR-M-star relation at the highest mass end up to a redshift z similar to 3.5. We interpret this turn-off as the signature of a strong on-going quenching mechanism and rapid mass growth. The sSFR increases strongly up to z similar to 2, but it grows much less rapidly in 2 \textless z \textless 5. We find that the shape of the sSFR evolution is not well reproduced by cold gas accretion-driven models or the latest hydrodynamical models. Below z similar to 2 these models have a flatter evolution (1+z)(Phi) with Phi = 2-2.25 compared to the data which evolves more rapidly with Phi = 2.8 +/- 0.2. Above z similar to 2, the reverse is happening with the data evolving more slowly with Phi = 1.2 +/- 0.1. The observed sSFR evolution over a large redshift range 0 \textless z \textless 5 and our finding of a non-linear main sequence at high mass both indicate that the evolution of SFR and M-star is not solely driven by gas accretion. The results presented in this paper emphasize the need to invoke a more complex mix of physical processes including major and minor merging to further understand the co-evolution of the SFR and stellar mass growth.

Mots clés: Galaxies: evolution; Galaxies: star formation; Galaxies: formation; Galaxies: high-redshift

Domaines: Astrophysique [astro-ph]

L. A. M. Tasca, O. Le Fevre, N. P. Hathi, D. Schaerer, O. Ilbert, et al.. The evolving star formation rate: M-star relation and sSFR since z similar or equal to 5 from the VUDS spectroscopic survey. Astronomy and Astrophysics - A&A, 2015, 581, ⟨10.1051/0004-6361/201425379⟩. ⟨hal-01439948⟩