11:00 am–12:00 pm ERC 401
Joshua Sobrin, "The SPT-3G Receiver and the First Galaxy Cluster Catalog from the SPT-3G Survey"
Committee Members: Bradford Benson (Chair), John Carlstrom, Craig Hogan, Stephan Meyer
Thesis abstract: Astronomical surveys of the cosmic microwave background (CMB) and large-scale structure (LSS) of the universe have provided empirical answers to many of the most profound questions in cosmology and particle astrophysics. In particular, these measurements have yielded some of the strongest pieces of evidence for ΛCDM, the prevailing standard model of cosmology describing the composition and underlying physics of the universe. Upcoming surveys aim to provide further insights --- for example, putting improved constraints on the properties and nature of dark energy, detecting the sum of the neutrino masses, and stress testing the standard cosmological model. In this dissertation, I will discuss the design and integrated performance of SPT-3G, the third survey receiver operating on the South Pole Telescope (a 10-meter diameter telescope designed for high-resolution observations of the CMB). In particular, I will provide details on the design, development, testing, and performance of the SPT-3G optics and cryogenics systems. Following this discussion, I will present the first galaxy-cluster sample constructed using SPT-3G data from the 2019 and 2020 observing seasons. The catalog contains 2457 candidates over 1500 deg^2, selected via the Sunyaev-Zel'dovich (SZ) effect with signal-to-noise ratios greater than 5. Because the formation history of galaxy clusters is expected to have strongly depended on the universe's physical conditions through time, measuring the abundance of galaxy clusters provides a unique way to probe the universe's LSS and evolution. The initial catalog presented in this work demonstrates the significant improvement in SZ-detection sensitivity provided by SPT-3G. In combination with optical/infrared measurements of the cluster candidates' redshifts and masses, the catalog is poised to put new constraints on cosmology, specifically on the nature of dark energy and neutrino mass.