Enhanced Star Formation in Both Disks and Ram-pressure-stripped Tails of GASP Jellyfish Galaxies

Exploiting the data from the GAs Stripping Phenomena in galaxies with MUSE (GASP) program, we compare the integrated star formation rate–mass relation (SFR–M*) relation of 42 cluster galaxies undergoing ram-pressure stripping (RPS; "stripping galaxies") to that of 32 field and cluster undisturbed galaxies. Theoretical predictions have so far led to contradictory conclusions about whether or not ram pressure can enhance the star formation (SF) in the gas disks and tails, and until now a statistically significant observed sample of stripping galaxies was lacking. We find that stripping galaxies occupy the upper envelope of the control sample SFR–M* relation, showing a systematic enhancement of the SFR at any given mass. The star formation enhancement occurs in the disk (0.2 dex), and additional SF takes place in the tails. Our results suggest that strong RPS events can moderately enhance the SF also in the disk prior to gas removal.