The Main Sequence of star-forming galaxies across cosmic times
Date Issued
2023
Author(s)
Popesso, P.
•
Concas, A.
•
•
Belli, S.
•
Rodighiero, G.
•
Inami, H.
•
Dickinson, M.
•
Ilbert, O.
•
•
Elbaz, D.
Abstract
By compiling a comprehensive census of literature studies, we investigate the
evolution of the Main Sequence (MS) of star-forming galaxies (SFGs) in the
widest range of redshift ($0 < z < 6$) and stellar mass ($10^{8.5}-10^{11.5}$
$M_{\odot}$) ever probed. We convert all observations to a common calibration
and find a remarkable consensus on the variation of the MS shape and
normalization across cosmic time. The relation exhibits a curvature towards the
high stellar masses at all redshifts. The best functional form is governed by
two parameters: the evolution of the normalization and the turnover mass
($M_0(t)$), which both evolve as a power law of the Universe age. The turn-over
mass determines the MS shape. It marginally evolves with time, making the MS
slightly steeper towards $z\sim4-6$. At stellar masses below $M_0(t)$, SFGs
have a constant specific SFR (sSFR), while above $M_0(t)$ the sSFR is
suppressed. We find that the MS is dominated by central galaxies. This allows
to turn $M_0(t)$ into the corresponding host halo mass. This evolves as the
halo mass threshold between cold and hot accretion regimes, as predicted by the
theory of accretion, where the central galaxy is fed or starved of cold gas
supply, respectively. We, thus, argue that the progressive MS bending as a
function of the Universe age is caused by the lower availability of cold gas in
halos entering the hot accretion phase, in addition to black hole feedback. We
also find qualitatively the same trend in the largest sample of star-forming
galaxies provided by the IllustrisTNG simulation. Nevertheless, we still note
large quantitative discrepancies with respect to observations, in particular at
the high mass end. These can not be easily ascribed to biases or systematics in
the observed SFRs and the derived MS.
Volume
519
Issue
1
Start page
1526
Issn Identifier
0035-8711
Rights
open.access
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