The relations between dust properties and galaxy global / integrated quantities in the nearby Universe

TL;DR

This study presents a new method to determine dust temperatures and emissivity indices in nearby galaxies, connecting dust properties with galaxy-wide quantities and exploring their correlations without full SED fitting.

Contribution

Introduces a less time-consuming method for estimating dust properties and analyzes their relation to galaxy characteristics, including the evolution of emissivity indices with temperature.

Findings

Dust temperatures are consistent with previous studies.

An anti-correlation between dust temperature and emissivity index is confirmed.

Relations between dust properties and galaxy star-formation metrics are analyzed.

Abstract

Results of a case study of a sample of low-redshift galaxies are presented, to determine dust temperatures and emissivity indices through a less time-consuming method, and to connect both global and integrated galaxy properties with those of dust, ISM and star-formation. Dust temperatures ($T_{d}$) are determined based on the corresponding galaxy dust masses, independently calculated in our previous work, through a self-consistent method, without the need to actually perform a complete spectral energy distribution (SED) fit of the cold dust emission fluxes. The range and average dust temperatures are found to be consistent within errors with values from other studies. Simultaneously, the dust emissivity indices ($\beta_{d}$) are determined, and their evolution with temperature quantified, with the $T_{d}$ anti-correlation still being present. It is investigated whether $\beta_{d}$ can be predicted from other relation or if it scales with other integrated dust / ISM or galaxy property, which could be used as a proxy. In this respect, new and established relations between $T_{d}$, $\beta_{d}$, the dust surface density and global / integrated galaxy and star-formation related quantities are presented and analysed. We find that SFR, sSFR or $\Sigma_{SFR}$ are inconclusive traces of the dust temperature. We also find that the extent of dust emission distribution is slightly lower on average, but comparable with the optical stellar continuum emission one. The results and conclusions can be relevant for larger scales studies of low to mid-redshift galaxies from the latest surveys.