GASP XXX. The spatially resolved SFR-Mass relation in stripping galaxies in the local universe

TL;DR

This study investigates the spatially resolved star formation rate-mass relation in 40 local galaxies undergoing ram pressure stripping, revealing a consistent enhancement in star formation due to compression effects across different galaxy regions.

Contribution

It provides the first detailed spatial analysis of the SFR-Mass relation in stripping galaxies, showing how ram pressure induces star formation enhancements at kiloparsec scales.

Findings

Stripping galaxies show a ~0.35 dex increase in Sigma_SFR compared to undisturbed galaxies.

The star formation excess is independent of stripping degree and present at all galactocentric distances.

Star-forming clumps in tails have higher star formation rates, but similar recent star formation histories as disk regions.

Abstract

The study of the spatially resolved Star Formation Rate-Mass (Sigma_SFR-Sigma_M) relation gives important insights on how galaxies assemble at different spatial scales. Here we present the analysis of the Sigma_SFR-Sigma_M of 40 local cluster galaxies undergoing ram pressure stripping drawn from the GAs Stripping Phenomena in galaxies (GASP) sample. Considering their integrated properties, these galaxies show a SFR enhancement with respect to undisturbed galaxies of similar stellar mass; we now exploit spatially resolved data to investigate the origin and location of the excess. Even on ~1kpc scales, stripping galaxies present a systematic enhancement of Sigma_SFR (~0.35 dex at Sigma_M =108^M_sun/kpc^2) at any given Sigma_M compared to their undisturbed counterparts. The excess is independent on the degree of stripping and of the amount of star formation in the tails and it is visible at all galactocentric distances within the disks, suggesting that the star formation is most likely induced by compression waves from ram pressure. Such excess is larger for less massive galaxies and decreases with increasing mass. As stripping galaxies are characterised by ionised gas beyond the stellar disk, we also investigate the properties of 411 star forming clumps found in the galaxy tails. At any given stellar mass density, these clumps are systematically forming stars at a higher rate than in the disk, but differences are reconciled when we just consider the mass formed in the last few 10^8yr ago, suggesting that on these timescales the local mode of star formation is similar in the tails and in the disks.