Assembling a RELIC at Redshift 1: Spectroscopic Observations of Galaxies in the RELICS Cluster SPT-CLJ0615-5746

Abstract

We present a catalog of spectroscopic redshifts for SPT-CLJ0615$-$5746, the most distant cluster in the Reionization Lensing Cluster Survey (RELICS). Using Nod & Shuffle multi-slit observations with LDSS-3 on Magellan, we identify $\sim 50$ cluster members and derive a cluster redshift of $z_c=0.972$, with a velocity dispersion of $\sigma =1235\pm 170\text{km}{\text{s}}^{-1}$. We calculate a cluster mass using a ${\sigma }_{200}-M_{200}$ scaling relation of $M_{200}=(9.4\pm 3.6)\times 10^{14}{M}_{\odot }$, in agreement with previous, independent mass measurements of this cluster. In addition, we examine the kinematic state of SPT-CLJ0615$-$5746, taking into consideration prior investigations of this system. With an elongated profile in lensing mass and X-ray emission, a non-Gaussian velocity dispersion that increases with clustercentric radius, and a brightest cluster galaxy not at rest with the bulk of the system, there are multiple cluster properties that, while not individually compelling, combine to paint a picture that SPT-CLJ0615$-$5746 is currently being assembled.

11 pages, 5 figures, 2 tables. Accepted for publication in The Astrophysical Journal

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Cited by in corpus (2)

• Dissecting the RELICS cluster SPT-CLJ0615-5746 through the intracluster light: confirmation of the multiple merging state of the cluster formation
• Resolving high-z Galaxy Cluster properties through joint X-ray and Millimeter analysis: a case study of SPT-CLJ0615-5746