AlFoCS + Fornax3D: resolved star formation in the Fornax cluster with ALMA and MUSE

TL;DR

This study combines ALMA and MUSE data to analyze the small-scale star formation relation in 9 Fornax cluster galaxies, revealing variations in depletion times and molecular cloud lifetimes, especially in disturbed dwarf galaxies.

Contribution

It provides the first resolved star formation analysis in Fornax cluster galaxies using combined ALMA and MUSE data, including molecular cloud lifetime estimates.

Findings

Star formation relation aligns with previous studies but shows shorter depletion times in dwarfs.

Depletion times vary significantly within galaxies, especially in disturbed regions.

Molecular cloud lifetimes are estimated to be less than 10 Myr in FCC290.

Abstract

We combine data from ALMA and MUSE to study the resolved (~300 pc scale) star formation relation (star formation rate vs. molecular gas surface density) in cluster galaxies. Our sample consists of 9 Fornax cluster galaxies, including spirals, ellipticals, and dwarfs, covering a stellar mass range of ~10^8.8 - 10^11 M_Sun. CO(1-0) and extinction corrected Halpha were used as tracers for the molecular gas mass and star formation rate, respectively. We compare our results with Kennicutt (1998) and Bigiel et al. (2008). Furthermore, we create depletion time maps to reveal small-scale variations in individual galaxies. We explore these further in FCC290, using the 'uncertainty principle for star formation' (Kruijssen & Longmore, 2014a) to estimate molecular cloud lifetimes, which we find to be short (<10 Myr) in this galaxy. Galaxy-averaged depletion times are compared with other parameters such as stellar mass and cluster-centric distance. We find that the star formation relation in the Fornax cluster is close to those from Kennicutt (1998) and Bigiel et al. (2008}), but overlaps mostly with the shortest depletion times predicted by Bigiel et al. (2008). This slight decrease in depletion time is mostly driven by dwarf galaxies with disturbed molecular gas reservoirs close to the virial radius. In FCC90, a dwarf galaxy with a molecular gas tail, we find that depletion times are a factor >~10 higher in its tail than in its stellar body.