The bending of the star-forming main sequence traces the cold- to hot-accretion transition mass over 0 < z < 4

Abstract

We analyse measurements of the evolving stellar mass (ℳ0 ) at which the bending of the star-forming main sequence (MS) occurs over 0 &lt; z &lt; 4. We find ℳ0 ≈ 1010 M⊙ over 0 &lt; z &lt; 1 before ℳ0 rises up to ∼1011 M⊙ at z = 2 and then stays flat or slowly increases towards higher redshifts. When converting ℳ0 values into hosting dark matter halo masses, we show that this behaviour is remarkably consistent with the evolving cold- to hot-accretion transition mass, as predicted by theory and defined by the redshift-independent Mshock at z &lt; 1.4 and by the rising Mstream at z ≳ 1.4 (for which we propose a revision in agreement with the latest simulations). We therefore argue that the MS bending is primarily due to a drop in cold accretion, causing a reduction in available cold gas in galaxies, which supports predictions of gas feeding theory. In particular, the rapidly rising ℳ0 with redshift at z &gt; 1 is evidence in favour of the cold-streams scenario. In this picture, a progressive fuelling reduction rather than its sudden suppression in halos more massive than Mshock/Mstream produces a nearly constant star-formation rate in galaxies with stellar masses larger than ℳ0, and not their quenching, which therefore requires other physical processes. Compared to the knee M* in the stellar mass function of galaxies, ℳ0 is significantly lower at z &lt; 1.5, and higher at z &gt; 2, suggesting that the imprint of gas deprivation on the distribution of galaxy masses happened at early times (z &gt; 1.5–2). The typical mass at which galaxies inside the MS become bulge-dominated evolves differently from ℳ0, which is consistent with the idea that bulge formation is a distinct process from the phasing out of cold accretion.

Bulge formation inside quiescent lopsided stellar disks: Connecting accretion, star formation, and morphological transformation in a z ∼ 3 galaxy group

“…Studying cSFG counterparts within such accretion-rich environments is our best bet at disentangling the effects of accretion and mergers. However, observationally establishing the presence of infalling cold-gas streams in halos has proved to be extremely challenging, with only a handful of convincing cases yet (using Ly-α emission as a tracer; Martin et al 2015Martin et al , 2019Umehata et al 2019;Daddi et al 2021Daddi et al , 2022a. Following up on one of these cases, we investigate the galaxy-group RO-1001 at z = 2.91 presented in Daddi et al (2021).…”

A super-linear ‘radio-AGN main sequence’ links mean radio-AGN power and galaxy stellar mass since z ∼ 3

“…8 (right), the RAMS normalisation at fixed M * clearly evolves with redshift (∝(1+z) 2.51±0.34 ), mimicking the evolution of the MS relation (e.g. Daddi et al 2022a) and the evolution of the molecular gas fraction in galaxies (roughly ∝(1+z) 2.5 ; e.g. Saintonge et al 2017;Tacconi et al 2018;Liu et al 2019;Tacconi et al 2020;Decarli et al 2020;Walter et al 2020, Wang et al 2022.…”

“…Thus, we adjust the new radio luminosity to match the L IR /L 1.4 ratio of a typical MS galaxy at a given (M * ,z). Specifically, we read L IR from the MS fitting form presented in Daddi et al (2022a; see their Table 1). They used median L IR measurements obtained in D21 via IR-mm stacking for the same sample of M * -selected SFGs.…”

“…10 by converting L SF 1.4 into SFR . To this end, we employ the z-evolving SFR-M * fitting form proposed by Lee et al (2015) but applied to the data from D21 (see Table 1 of Daddi et al 2022a). The resulting expression reads as follows: log…”

The Black Hole Mass Function across Cosmic Time. II. Heavy Seeds and (Super)Massive Black Holes

“…First, we vary the main-sequence relationship, switching from Speagle et al (2014) (2014), the above is characterized by a steepening toward the lower stellar masses and a progressive flattening toward higher stellar masses that have some relevance in galaxy formation, since they may be interpreted as the effects of stellar feedback and mass quenching, respectively (e.g., Lapi et al 2018;Daddi et al 2022). Second, we vary the shape of the declining portion of the accretion rate curve in Equation (9).…”