paper

An evolving and mass dependent - relation for galaxies

arXiv:1905.02023 · doi:10.3847/1538-4357/ab1f8d

Abstract

The scatter () of the specific star formation rates (sSFRs) of galaxies is a measure of the diversity in their star formation histories (SFHs) at a given mass. In this paper we employ the EAGLE simulations to study the dependence of the of galaxies on stellar mass () through the - relation in . We find that the relation evolves with time, with the dispersion depending on both stellar mass and redshift. The models point to an evolving U-shape form for the - relation with the scatter being minimal at a characteristic mass of and increasing both at lower and higher masses. This implication is that the diversity of SFHs increases towards both at the low- and high-mass ends. We find that active galactic nuclei feedback is important for increasing the for high mass objects. On the other hand, we suggest that SNe feedback increases the of galaxies at the low-mass end. We also find that excluding galaxies that have experienced recent mergers does not significantly affect the - relation. Furthermore, we employ the combination of the EAGLE simulations with the radiative transfer code SKIRT to evaluate the effect of SFR/stellar mass diagnostics in the - relation and find that the methodologies (e.g. SED fitting, UV+IR, UV+IRX-) widely used in the literature to obtain intrinsic properties of galaxies have a large effect on the derived shape and normalization of the - relation.

23 pages, 10 figures, Accepted to ApJ

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