Dust Temperature and Emission of FirstLight Simulated Galaxies at Cosmic Dawn

Abstract: We study the behavior of dust temperature and its infrared emission of FirstLight1 simulated galaxies at the redshift of 6 and 8, by using POLARIS2 as a Monte Carlo photon transport simulator. To calculate the dust temperature ($T_{dust}$) of the Interstellar medium (ISM) of galaxies, POLARIS requires three essential parameters as an input - (1) The physical characteristics of galaxies such as the spatial distribution of stars and dust, which are taken from FirstLight galaxies. (2) The intrinsic properties of dust grains that are derived from theDiscrete Dipole Approximation Code (DDSCAT) model. (3) The optical properties of star-particles are in the form of their spectral energy distributions (SEDs) which are extracted from the Binary Population and Spectral Synthesis (BPASS) model. Our simulations produced the 3D maps of the equilibrium dust temperature along with the sight-line infrared emission maps of galaxies. Our results show the importance of excess heating of dust by the Cosmic Microwave Background (CMB) radiations at high redshifts that results in increased Mid and Far infrared (M-FIR) dust emission. The different evaluations of dust temperature models relate diversely to the optical and intrinsic properties of galaxies