Dynamical properties of z $\sim 4.5$ dusty star-forming galaxies and their connection with local early type galaxies

Abstract

There is a large consensus that gas in high-𝑧 galaxies is highly turbulent, because of a combination of stellar feedback processes and gravitational instabilities driven by mergers and gas accretion. In this paper, we present the analysis of a sample of five Dusty Star Forming Galaxies (DSFGs) at 4 𝑧 5. Taking advantage of the magnifying power of strong gravitational lensing, we quantified their kinematic and dynamical properties from ALMA observations of their [CII] emission line. We combined the dynamical measurements obtained for these galaxies with those obtained from previous studies to build the largest sample of 𝑧 ∼ 4.5 galaxies with high-quality data and sub-kpc spatial resolutions, so far. We found that all galaxies in the sample are dynamically cold, with rotation-to-random motion ratios, 𝑉/𝜎, between 7 to 15. The relation between their velocity dispersions and their star-formation rates indicates that stellar feedback is sufficient to sustain the turbulence within these galaxies and no further mechanisms are needed. In addition, we performed a rotation curve decomposition to infer the relative contribution of the baryonic (gas, stars) and dark matter components to the total gravitational potentials. This analysis allowed us to compare the structural properties of the studied DSFGs with those of their descendants, the local early type galaxies. In particular, we found that five out of six galaxies of the sample show the dynamical signature of a bulge, indicating that the spheroidal component is already in place at 𝑧 ∼ 4.5.

High [OIII]/[CII] surface brightness ratios trace early starburst galaxies

“…High κs values result in short depletion times, t dep = 6 − 49 Myr. This is in line with resolved t dep values derived in a handful of dusty star forming galaxies (DSFGs) at z ≈ 3.5 − 5: t dep = 50 − 200 Myr (Hodge et al 2015), t dep = 1 − 30 Myr (Rybak et al 2020), and t dep = 12 − 357 Myr (Rizzo et al 2021). Our analysis thus suggests that joint [CII]-[OIII] emitters, despite not being as dusty as DSFGs, share comparable levels of star formation activity.…”

The MUSE Extremely Deep Field: Evidence for SFR-induced cores in dark-matter dominated galaxies at z=1

“…Gentile et al 2004;Spano et al 2008;Donato et al 2009;Allaert et al 2017;Katz et al 2017;Korsaga et al 2018;Di Paolo et al 2019) or in massive early type galaxies often aided by gravitational lensing (e.g. Suyu et al 2010;Newman et al 2013;Sonnenfeld et al 2012Sonnenfeld et al , 2013Sonnenfeld et al 2015;Oldham & Auger 2018;Wasserman et al 2018), but the core/cusp nature of DM is rarely investigated in SFGs outside the local universe (except in Genzel et al 2020;Rizzo et al 2021) because this is a challenging task. However, owing to the high DM fractions in our sample (see Fig.…”

“…Most relevant for this paper, disk-halo decompositions of distant galaxies have been performed with 3D Barolo at z 4 on bright submm [CII] ALMA sources (Rizzo et al 2020;Neeleman et al 2020;Fraternali et al 2021). In addition, when used in combination with stacking or lensing, 3D algorithms are powerful tools to extract resolved kinematics at very high-redshifts as in Rizzo et al (2021).…”