The morphological transformation of ram pressure stripped galaxies: a pathway from late to early galaxy types

We investigate how the ageing of stellar populations can drive a morphological transformation in galaxies whose star formation (SF) activity has been quenched on short time-scales, like in cluster galaxies subject to ram pressure stripping from the intracluster medium. For this purpose, we use a sample of 91 galaxies with MUSE data from the GAs Stripping Phenomena in galaxies with MUSE (GASP) programme and of their spatially resolved SF history derived with the spectral modelling software SINOPSIS. We simulate the future continuation of the SF activities by exploring two quenching scenarios: an instantaneous truncation of the SF across the whole disc, and an outside-in quenching with typical stripping time-scales of 0 . 5 and 1 Gyr . For each scenario, we produce mock MUSE spectroscopic data cubes and optical images for our galaxies during their evolution, and classify their morphology using a new diagnostic tool, calibrated on cluster galaxies from the Ome gaWINGS Surv e y. We find that, in all scenarios considered, the initial galaxy population dominated by blue-cloud spirals (similar to 90 per cent ) evolves into a mixed population mostly composed by red-sequence spirals (50 -55 per cent ) and lenticulars (similar to 40 per cent ). The morphology transformation is completed after just 1.5-3.5 Gyr, proceeding faster in more efficient quenching scenarios. Our results indicate that, even without accounting for dynamical processes, SF quenching caused by the harsh environment of a cluster can significantly affect the morphology of the infalling galaxy population on timescales of a few Gyr.