Presentation #101.09 in the session Galaxy Clusters/Large Scale Structures.
With the rapid improvement in sensitivity of Sunyaev-Zel'dovich (SZ) surveys, we are becoming increasingly capable of discovering galaxy clusters at high redshift (z > 1). Substantial investments have been made with both Chandra and XMM-Newton to follow these systems up with X-ray observations with the goal of understanding galaxy cluster evolution. However, such studies hinge on our understanding of the population statistics of the high-mass, low-z clusters. Existing surveys of such systems are biased in a variety of ways, the most common being towards the presence of cool cores. With this in mind, we have designed the Low-z UNbiased CHandra (LUNCH) galaxy cluster sample, a complete sample of 108 low-z galaxy clusters observed with Chandra. These 108 clusters were cleanly selected from the Planck 2nd SZ Survey, and they have masses spanning the range between that of the Perseus cluster and that of the Coma cluster as well as a narrow redshift spread of z = 0.2 ± 0.05. They correspond to the descendants of the clusters that we expect to observe at z>2 with the third-generation detector on the South Pole Telescope (SPT-3G). We are using the LUNCH galaxy cluster sample to characterize the population statistics of low-z clusters. Our primary goals are to understand cluster demographics at z=0.2, including: (i) the cool core fraction, (ii) the major merger rate, (iii) the sloshing fraction, and (iv) the mean thermodynamic profiles. In the future, we plan to extend this work to consider the demographics of brightest cluster galaxies, their central AGN, and how these are connected to the host cluster. These studies will provide an anchor for evolutionary studies with future X-ray observatories such as AXIS, Athena, and STAR-X.