Deriving the intrinsic properties of M51 with radiative transfer models

TL;DR

This study develops a radiative transfer model for galaxy M51, accurately reproducing its spectral and spatial energy distribution across multiple wavelengths to derive intrinsic properties of its components.

Contribution

It introduces a self-consistent, axi-symmetric RT model constrained by multi-wavelength imaging data, including a novel approach with variable dust properties within the galaxy.

Findings

Model reproduces radial profiles from UV to submm wavelengths.

Identifies a faint outer disc connecting M51 with M51b.

Provides intrinsic parameters of stellar and dust components.

Abstract

A quantitative derivation of the intrinsic properties of galaxies related to their fundamental building blocks, gas, dust and stars is essential for our understanding of galaxy evolution. A fully self-consistent derivation of these properties can be achieved with radiative transfer (RT) methods that are constrained by panchromatic imaging observations. Here we present an axi-symmetric RT model of the UV-optical-FIR/submm spectral and spatial energy distribution of the face-on spiral galaxy M51. The model reproduces reasonably well the azimuthally averaged radial profiles derived from the imaging data available for this galaxy, from GALEX, SDSS, 2MASS, Spitzer and Herschel. We model the galaxy with three distinct morphological components: a bulge, an inner disc and a main disc. We derive the length parameters of the stellar emissivity and of the dust distribution. We also derive the intrinsic global and spatially resolved parameters of M51. We find a faint \lq\lq outer disc\rq\rq\ bridging M51 with its companion galaxy M51b. Finally, we present and discuss an alternative model, with dust properties that change within the galaxy.