Where stars form and live at high redshift: clues from the infrared

¹ Laboratoire AIM-Paris-Saclay, CEA/DSM/Irfu, CNRS, Univ. Paris Diderot, Saclay, France
e-mail: matthieu.bethermin@cea.fr
² Institut d’Astrophysique Spatiale (IAS), Bat. 121, 91405 Orsay, France ; Université Paris-Sud 11 and CNRS (UMR8617), France
³ Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, Pasadena, California, USA
⁴ California Institute of Technology, Pasadena, California, USA

Received: 7 December 2011
Accepted: 24 December 2011

Abstract

The relation between dark matter halos and the loci of star formation at high redshift is a pressing question in contemporary cosmology. Matching the abundance of halos to the abundance of infrared (IR) galaxies, we explore the link between dark matter halo mass (M_h), stellar mass (M_⋆) and star-formation rate (SFR) up to a redshift of 2. Our findings are five-fold. First, we find a strong evolution of the relation between M_⋆ and SFR as a function of redshift with an increase of sSFR  =  SFR/M_⋆ by a factor  ~30 between z = 0 and z = 2.3. Second, we observe a decrease of sSFR with stellar mass. These results reproduce observed trends at redshift z > 0.3. Third, we find that the star formation is most efficient in dark matter halos with M_h ≃ 5 × 10¹¹ M_⊙, with hints of an increase of this mass with redshift. Fourth, we find that SFR/M_h increases by a factor  ~15 between z = 0 and z = 2.3. Finally we find that the SFR density is dominated by halo masses close to  ~7 × 10¹¹   M_⊙ at all redshift, with a rapid decrease at lower and higher halo masses. Despite its simplicity, our novel use of IR observations unveils some characteristic mass-scales governing star formation at high redshift.