GASP XXI. Star formation rates in the tails of galaxies undergoing ram-pressure stripping

TL;DR

This study uses MUSE observations from the GASP survey to analyze star formation in the tails of 54 galaxies undergoing ram-pressure stripping, developing a model to relate SFR in tails to galaxy and cluster properties.

Contribution

It introduces a simple analytical model linking star formation rates in stripped tails to cluster and galaxy parameters, accounting for reduced star formation efficiency.

Findings

The SFR in tails is approximately 0.22 solar masses per year per cluster.

Star formation efficiency in tails is about five times lower than in galaxy disks.

Estimated total stellar mass formed in tails since z~1 is around 4 billion solar masses.

Abstract

Using MUSE observations from the GASP survey, we study 54 galaxies undergoing ram-pressure stripping (RPS) spanning a wide range in galaxy mass and host cluster mass. We use this rich sample to study how the star formation rate (SFR) in the tails of stripped gas depends on the properties of the galaxy and its host cluster. We show that the interplay between all the parameters involved is complex and that there is not a single, dominant one in shaping the observed amount of SFR. Hence, we develop a simple analytical approach to describe the mass fraction of stripped gas and the SFR in the tail, as a function of the cluster velocity dispersion, galaxy stellar mass, clustercentric distance and speed in the intracluster medium. Our model provides a good description of the observed gas truncation radius and of the fraction of star-formation rate (SFR) observed in the stripped tails, once we take into account the fact that the star formation efficiency in the tails is a factor $\sim 5$ lower than in the galaxy disc, in agreement with GASP ongoing HI and CO observations. We finally estimate the contribution of RPS to the intracluster light (ICL) and find that the average SFR in the tails of ram-pressure stripped gas is $\sim 0.22 M_{\odot}\,\mathrm{yr}^{-1} $ per cluster. By extrapolating this result to evaluate the contribution to the ICL at different epochs, we compute an integrated average value per cluster of $\sim 4 \times 10^9 M_\odot$ of stars formed in the tails of RPS galaxies since $z\sim 1$.