PÉGASE.3: A code for modeling the UV-to-IR/submm spectral and chemical evolution of galaxies with dust^⋆,⋆⋆

¹ Sorbonne Université, CNRS, UMR 7095, Institut d’astrophysique de Paris, 98 bis boulevard Arago, 75014 Paris, France
e-mail: Michel.Fioc@iap.fr
² Université Paris-Sud, 91405 Orsay, France
e-mail: Brigitte.Rocca@iap.fr

Received: 2 June 2018
Accepted: 19 December 2018

Abstract

A code computing consistently the evolution of stars, gas and dust, as well as the energy they radiate, is required to derive reliably the history of galaxies by fitting synthetic spectral energy distributions (SEDs) to multiwavelength observations. The new code PÉGASE.3 described in this paper extends to the far-infrared/submillimeter the ultraviolet-to-near-infrared modeling provided by previous versions of PÉGASE. It first computes the properties of single stellar populations at various metallicities. It then follows the evolution of the stellar light of a galaxy and the abundances of the main metals in the interstellar medium (ISM), assuming some scenario of mass assembly and star formation. It simultaneously calculates the masses of the various grain families, the optical depth of the galaxy and the attenuation of the SED through the diffuse ISM in spiral and spheroidal galaxies, using grids of radiative transfer precomputed with Monte Carlo simulations taking scattering into account. The code determines the mean radiation field and the temperature probability distribution of stochastically heated individual grains. It then sums up their spectra to yield the overall emission by dust in the diffuse ISM. The nebular emission of the galaxy is also computed, and a simple modeling of the effects of dust on the SED of star-forming regions is implemented. The main outputs are ultraviolet-to-submillimeter SEDs of galaxies from their birth up to 20 Gyr, colors, masses of galactic components, ISM abundances of metallic elements and dust species, supernova rates. The temperatures and spectra of individual grains are also available. The paper discusses several of these outputs for a scenario representative of Milky Way-like spirals. PÉGASE.3 is fully documented and its Fortran 95 source files are public. The code should be especially useful for cosmological simulations and to interpret future mid- and far-infrared data, whether obtained by JWST, LSST, Euclid or e-ELT.