Dusty galaxies in the Epoch of Reionization: simulations

C. Behrens; A. Pallottini; A. Ferrara; S. Gallerani; L. Vallini

doi:10.1093/mnras/sty552

paper

Dusty galaxies in the Epoch of Reionization: simulations

arXiv:1802.07772 · doi:10.1093/mnras/sty552

Abstract

The recent discovery of dusty galaxies well into the Epoch of Reionization (redshift $z > 6$ ) poses challenging questions about the properties of the interstellar medium in these pristine systems. By combining state-of-the-art hydrodynamic and dust radiative transfer simulations, we address these questions focusing on the recently discovered dusty galaxy A2744_YD4 ( $z = 8.38$ , Laporte et al. 2017}). We show that we can reproduce the observed spectral energy distribution (SED) only using different physical values with respect to the inferred ones by Laporte et al(2017), i.e. a star formation rate of $SFR = 78 M_{⊙} y r^{- 1}$ , a factor $\approx 4$ higher than deduced from simple Spectral Energy Distribution fitting. In this case we find: (a) dust attenuation (corresponding to $τ_{V} = 1.4$ ) is consistent with a Milky Way extinction curve; (b) the dust-to-metal ratio is low, $f_{d} \sim 0.08$ , implying that early dust formation is rather inefficient; (c) the luminosity-weighted dust temperature is high, $T_{d} = 91 \pm 23 K$ , as a result of the intense ( $\approx 100 \times$ MW) interstellar radiation field; (d) due to the high $T_{d}$ , the ALMA Band 7 detection can be explained by a limited dust mass, $M_{d} = 1.6 \times 1 0^{6}$ M $_{⊙}$ . Finally, the high dust temperatures might solve the puzzling low infrared excess recently deduced for high- $z$ galaxies from the IRX- $β$ relation.

arXiv comment15 pages, accepted for publication in MNRAS

Dusty galaxies in the Epoch of Reionization: simulations

Abstract

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