Evidence for enhanced star formation rates in z ∼ 0.35 cluster galaxies undergoing ram pressure stripping

Ram-pressure stripping (RPS) is the mechanism most often invoked to explain the observed differences between cluster and field galaxies. In the local Universe, its effect on the star-forming properties of the galaxies has been largely elucidated and the general consensus is that this process first compresses the gas available in galaxy disks, boosting the star formation for a limited amount of time, and then removes the remaining gas, leading to quenching. Much less is known about the effect and preponderance of RPS at higher redshifts, due to the lack of statistical samples. Exploiting VLT/MUSE observations of galaxies at 0.2 < z < 0.55 and a published catalog of ram-pressure-stripped galaxies, we compare the global star formation rate-mass (SFR-M_*) relation of 29 cluster galaxies undergoing RPS to that of 26 undisturbed field and cluster galaxies that constitute our control sample. Stripping galaxies occupy the upper envelope of the SFR-M_* relation of the control sample, showing a systematic enhancement of SFR at any given mass. The boost is > 3σ when considering the SFR occurring in both the tail and the disk of the galaxies. The enhancement is also seen on local scales: Considering spatially resolved data, ram-pressure stripped galaxies have large Σ_SFR values overall, especially for Σ_* > 10^7.5 M_⊙ kpc⁻². RPS seems to leave the same imprint on the SFR-M_* and Σ_SFR-Σ_* relations both in the local Universe and at z ∼ 0.35.

Full Table 1 is available at the CDS via anonymous ftp to cdsarc.cds.unistra.fr (ftp://130.79.128.5) or via https://cdsarc.cds.unistra.fr/viz-bin/cat/J/A+A/682/A117