The impact of the Star Formation Histories on the SFR-M$_{*}$ relation at z$\ge$2

TL;DR

This study examines how different star formation histories influence the observed relation between stellar mass and star formation rate in high-redshift galaxies, highlighting the importance of SFH assumptions in SED fitting.

Contribution

It introduces a comprehensive analysis of SFH effects on the SFR-M* relation at z≥2 using a new library of models and advanced SED fitting techniques.

Findings

Most galaxies are best-fit by models with high $ au_{infall}/ u$ ratios.

The scatter in the SFR-M* relation is mainly due to SFH choices in SED fitting.

Redshift has a minor effect compared to SFH assumptions.

Abstract

In this paper we investigate the impact of different star formation histories (SFHs) on the relation between stellar mass M$_{*}$ and star formation rate (SFR) using a sample of galaxies with reliable spectroscopic redshift zspec>2 drawn from the VIMOS Ultra-Deep Survey (VUDS). We produce an extensive database of dusty model galaxies, calculated starting from the new library of single stellar population (SSPs) models presented in Cassara' et al. 2013 and weighted by a set of 28 different SFHs based on the Schmidt function, and characterized by different ratios of the gas infall time scale $\tau_{infall}$ to the star formation efficiency $\nu$. The treatment of dust extinction and re-emission has been carried out by means of the radiative transfer calculation. The spectral energy distribution (SED) fitting technique is performed by using GOSSIP+, a tool able to combine both photometric and spectroscopic information to extract the best value of the physical quantities of interest, and to consider the Intergalactic Medium (IGM) attenuation as a free parameter. We find that the main contribution to the scatter observed in the $SFR-M_{*}$ plane is the possibility of choosing between different families of SFHs in the SED fitting procedure, while the redshift range plays a minor role. The majority of the galaxies, at all cosmic times, are best-fit by models with SFHs characterized by a high $\tau_{\rm infall}/\nu$ ratio. We discuss the reliability of the presence of a small percentage of dusty and highly star forming galaxies, in the light of their detection in the FIR.