The REBELS ALMA Survey: cosmic dust temperature evolution out to z $\sim$ 7

L. Sommovigo; A. Ferrara; A. Pallottini; P. Dayal; R. J. Bouwens; R. Smit; E. da Cunha; I. De Looze; R. A. A. Bowler; J. Hodge; H. Inami; P. Oesch; R. Endsley; V. Gonzalez; S. Schouws; D. Stark; M. Stefanon; M. Aravena; L. Graziani; D. Riechers; R. Schneider; P. van der Werf; H. Algera; L. Barrufet; Y. Fudamoto; A. P. S. Hygate; I. Labbé; Y. Li; T. Nanayakkara; M. Topping

doi:10.1093/mnras/stac302

paper

The REBELS ALMA Survey: cosmic dust temperature evolution out to z $\sim$ 7

arXiv:2202.01227 · doi:10.1093/mnras/stac302

Abstract

ALMA observations have revealed the presence of dust in the first generations of galaxies in the Universe. However, the dust temperature $T_{d}$ remains mostly unconstrained due to the few available FIR continuum data at redshift $z > 5$ . This introduces large uncertainties in several properties of high- $z$ galaxies, namely their dust masses, infrared luminosities, and obscured fraction of star formation. Using a new method based on simultaneous [CII] 158 $μ$ m line and underlying dust continuum measurements, we derive $T_{d}$ in the continuum and [CII] detected $z \approx 7$ galaxies in the ALMA Large Project REBELS sample. We find $39 K < T_{d} < 58 K$ , and dust masses in the narrow range $M_{d} = (0.9 - 3.6) \times 1 0^{7} M_{⊙}$ . These results allow us to extend for the first time the reported $T_{d} (z)$ relation into the Epoch of Reionization. We produce a new physical model that explains the increasing $T_{d} (z)$ trend with the decrease of gas depletion time, $t_{d e p} = M_{g} / SFR$ , induced by the higher cosmological accretion rate at early times; this hypothesis yields $T_{d} \propto (1 + z)^{0.4}$ . The model also explains the observed $T_{d}$ scatter at a fixed redshift. We find that dust is warmer in obscured sources, as a larger obscuration results in more efficient dust heating. For UV-transparent (obscured) galaxies, $T_{d}$ only depends on the gas column density (metallicity), $T_{d} \propto N_{H}^{1/6}$ ( $T_{d} \propto Z^{- 1/6}$ ). REBELS galaxies are on average relatively transparent, with effective gas column densities around $N_{H} ≃ (0.03 - 1) \times 1 0^{21} cm^{- 2}$ . We predict that other high- $z$ galaxies (e.g. MACS0416-Y1, A2744-YD4), with estimated $T_{d} ≫ 60$ K, are significantly obscured, low-metallicity systems. In fact $T_{d}$ is higher in metal-poor systems due to their smaller dust content, which for fixed $L_{I R}$ results in warmer temperatures.

arXiv commentAccepted for publication in MNRAS

The REBELS ALMA Survey: cosmic dust temperature evolution out to z $\sim$ 7

Abstract

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The REBELS ALMA Survey: cosmic dust temperature evolution out to z ∼ 7

Abstract

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Cited by in corpus (63)

The REBELS ALMA Survey: cosmic dust temperature evolution out to z $\sim$ 7