The Star Formation Reference Survey III: A Multi-wavelength View of Star Formation in Nearby Galaxies

TL;DR

This study compares various multi-wavelength star formation rate indicators across 326 nearby galaxies, finding they are generally consistent within 0.3 dex and highlighting the importance of non-linear relations and extinction corrections.

Contribution

It provides a comprehensive analysis of multiple SFR indicators, assessing their mutual scatter and validity, and offers insights into the effects of extinction corrections in galaxy star formation measurements.

Findings

Empirical SFR recipes are consistent within 0.3 dex scatter.

A non-linear relation exists between 1.4 GHz luminosity and other SFR measures.

UV spectral slope can reliably estimate extinction for certain galaxy subsets.

Abstract

We present multi-wavelength global star formation rate (SFR) estimates for 326 galaxies from the Star Formation Reference Survey (SFRS) in order to determine the mutual scatter and range of validity of different indicators. The widely used empirical SFR recipes based on 1.4 GHz continuum, 8.0 $\mu$m polycyclic aromatic hydrocarbons (PAH), and a combination of far-infrared (FIR) plus ultraviolet (UV) emission are mutually consistent with scatter of $\raise{-0.8ex}\stackrel{\textstyle <}{\sim }$0.3 dex. The scatter is even smaller, $\raise{-0.8ex}\stackrel{\textstyle <}{\sim }$0.24 dex, in the intermediate luminosity range 9.3<log(L(60 $\mu$m/L$_\odot$)<10.7. The data prefer a non-linear relation between 1.4 GHz luminosity and other SFR measures. PAH luminosity underestimates SFR for galaxies with strong UV emission. A bolometric extinction correction to far-ultraviolet luminosity yields SFR within 0.2 dex of the total SFR estimate, but extinction corrections based on UV spectral slope or nuclear Balmer decrement give SFRs that may differ from the total SFR by up to 2 dex. However, for the minority of galaxies with UV luminosity ${>}5\times10^9$ L$_{\odot}$ or with implied far-UV extinction <1 mag, the UV spectral slope gives extinction corrections with 0.22~dex uncertainty.