Oral Presentation
Anisotropic Quenching beyond z=1: A New Probe of Pre-Processing around Cosmic Noon
Presenter: Makoto Ando (National Astronomical Observatory of Japan)
Recent studies have shown that, within galaxy clusters, quenched satellite galaxies tend to be distributed preferentially along the major axis of the central galaxy (i.e. BCG), dubbed as anisotropic satellite galaxy quenching (ASGQ). The physical origin of ASGQ at low-redshift Universe (z<0.5) has been investigated and suggested to be the pre-processing effects (i.e. quenching occurs within the cosmic filaments that connect clusters). However, it remains unclear whether ASGQ had already emerged in the earlier Universe and what its physical origin might be. Our previous study has successfully detected ASGQ up to redshift z=1. This study further investigates ASGQ beyond z=1 and its physical origin. Twelve confirmed clusters at 0.9 < z < 1.4 are taken from a public cluster survey (GOGREEN), and their memberships are determined based on reliable photometric redshifts. We examine the angular dependence of quiescent satellite fraction and detect ASGQ for the first time at these redshifts, despite the modest (>~ 2-sigma level) statistical significance. To further understand the origin of the observed ASGQ, we adopt a semi-analytic approach based on a halo accretion history onto clusters extracted from a cosmological simulation and a toy anisotropic quenching model that parameterizes both intra-halo quenching and pre-preprocessing effects. We fit our model to the observed ASGQ at z>1 and find that the observed ASGQ can be explained mainly by the pre-processing effects. This suggests that ASGQ can be used to indicate the progress of the pre-processing around the high-redshift clusters.
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