Probing environmental quenching in the Fornax cluster through a population-orbital superposition method

Recent observations of gas metallicities in cluster galaxies have provided tentative evidence of slow-then-rapid quenching: when galaxies enter the cluster their external gas supply is cut off, but star formation in a disk continues for another 1-2 Gyr before suddenly quenched (e.g., Maier et al. 2019). Environmental quenching can thus be probed by the age and metallicities of the stars in these 'residual' disks. The problem, however, is to extract the age and metallicity of these particular disk stars from the rest of the galaxy, which are mixed along line-of-sight. We overcome this difficulty by applying the recently developed population-orbit superposition method (Zhu+2020) to each of 23 early-type galaxies in Fornax cluster observed by MUSE/VLT. Our preliminary results suggest that star formation in disks could last for ~2 Gyrs after infall or even continue till today, depending on a galaxy's location in the cluster and its content of gas before falling into the cluster.