Meet the Neighbors: Gas Rich "Buddy Galaxies" are Common Around Recently Quenched Massive Galaxies in the SQuIGG$\vec{L}$E Survey

Abstract

In this work, we characterize the environments of massive ($\log (M_{\odot }/M_{\star })\sim 11.2$) $z\sim 0.7$ post-starburst galaxies (PSBs) by studying serendipitously-detected CO(2-1) emitters found in targeted observations of the SQuIGG$\vec{L}$E sample. We report $31\pm 6\%$ of the galaxies from this survey host nearby gas-rich ``buddies'' with stellar masses $\ge 10^{10},M_{\odot }$ and molecular gas comparable to their central PSBs ($M_{H_2}\sim 10^{10}{M}_{\odot }$), but $\sim 0.8$ dex lower stellar mass ($\sim 10^{10.4}{M}_{\odot }$). Based on their location in position-velocity space, each buddy is consistent with being bound to the haloes of their SQuIGG$\vec{L}$E host galaxies. We compare to the UniverseMachine model and find that SQuIGG$\vec{L}$E galaxies host a typical number of neighbors for their stellar mass, suggesting that PSBs live in environments typical of co-eval similarly-massive galaxies.

Research Notes of the American Astronomical Society (RNAAS); 4 pages, 1 figure. This work is complemented by a companion paper, Setton et al., which presents the molecular gas properties of the host post-starburst galaxies

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• Quenching in the Right Place at the Right Time: Tracing the Shared History of Starbursts, AGNs, and Post-starburst Galaxies Using Their Structures and Multiscale Environments