Author(s): , ,
Institution(s): 1. CNRS, 2. IAP
There is now a firmly established so-called “Main Sequence” (MS) of starforming galaxies where galaxies forming stars lie on a tight power law sequence in the stellar mass (M∗), star formation rate (SFR) plane, with a flattening at the high mass end. Originally observed at z ∼ 0 in the SDSS it has now been measured up to z~7.
Very early on, it was recognized that the evolution of the sSFR with redshift along the MS mimic that of the accretion rate onto dark matter halos, both as a function of halo mass and redshift (Bouché et al. 2010). Yet, detailed simulations of galaxy evolution including baryon accretion and feedback have difficulties in reproducing the observed evolution of the MS from high to low redshift with standard recipes (Dave et al., 2011, Weinmann et al., 2011).
Instead of trying to improve the agreement of simulations with the observations by modifying the sub-grid recipes of baryons, we take here a step back to check whether the accretion onto dark matter halos is consistent with the existence of the main sequence of star forming galaxies. Various technique have been developped in recent years to connect galaxies through their stellar mass to their host halo mass, so that a direct comparison between the accretion properties of halos and their hosted galaxies SFR is now possible. Moreover, measure of the gas content of galaxies along the main sequence are becoming available up to z~5 thanks to Alma and PdBI, further constraining the level of the gas reservoir available for star formation as a function of redshift.
We have therefore used a large pure dark-matter simulation with minimal prescriptions for the baryons to study the accretion onto dark matter halos and compared it with the observed properties of star forming galaxies. Our results show that the accretion on DM halos is compatible with the observed evolution of the MS and the gas content of galaxies with redshift as well as with the observed scatter of these relations. This allow us to place constraint on the level of feedback as a function of halo mass and redshift that have to take place inside the halos in order for the baryons to reproduce the observed trends.