Oral Presentation

Anisotropic satellite quenching in galaxy clusters up to z~1 detected by the HSC-SSP survey

Author(s): Makoto Ando, Kazuhiro Shimasaku, Kei Ito (The University of Tokyo)

Presenter: Makoto Ando (The University of Tokyo)

Satellite galaxies in the cluster environment are more likely to be quenched than galaxies in the general field. Recently, it has been reported that satellite galaxy quenching depends on the orientation relative to their central galaxies: satellites along the major axis of centrals are more likely to be quenched than those along the minor axis. We report a detection of such anisotropic quenching up to z~1 based on a large (N>5000) optically-selected cluster catalogue, (CAMIRA; Oguri et al. 2018), constructed from the Hyper Suprime-Cam Subaru Strategic Program (Aihara et al. 2022). We calculate the quiescent satellite galaxy fraction as a function of orientation angle measured from the major axis of central galaxies and find that the quiescent fractions at 0.25r_200). We also find that the observed anisotropy cannot be explained by differences in local galaxy density or stellar mass distribution along the two axes. We argue that the physical origins of the observed anisotropy should have shorter quenching timescales (~1 Gyr), like ram-pressure stripping, because, for anisotropic quenching to be observed, satellites must be quenched before their initial orientation angles are significantly changed.