Exploring Infrared-Bright Sources Detected by the South Pole Telescope - Lensing Galaxies and the Most Massive Structures in the Universe

• Main Author: Rotermund, Kaja M.
• Other Authors: Department of Physics & Atmospheric Science, Doctor of Philosophy, Tracy Webb, Theodore Monchesky, Philip Bennett, Scott Chapman, Not Applicable, Yes
• Language: English
• Published: 2020
• Subjects: gravitational lensing; sub-millimetre galaxies; proto-clusters; photo-lithography; cosmic microwave background; South Pole; South pole
• Online Access: http://hdl.handle.net/10222/78524

The work in this thesis presents advances in the field of astrophysics - exploring the exciting (and unexpected) secondary science from millimetre-wave cosmology experiments as well as the development of a novel cold-readout system that improves the sensitivity of said experiments. The South Pole Telescope, whose primary science objectives include measuring the temperature anisotropy and polarization of the cosmic microwave background, conducted a 2,500 deg^2 survey and detected a population of rare, bright, high-redshift, dusty, star-forming galaxies whose light is frequently magnified and distorted by gravitational lensing, a phenomenon predicted by Einstein. In Chapter 2 we explore the gravitational lenses - massive, passively evolving elliptical galaxies. Multi-band photometric imaging allows us to determine a redshift distribution for the lenses and estimate astrophysical properties such as galaxy type (using a variety of diagnostics) as well as stellar mass and Einstein mass. In Chapter 3 we focus on SPT2349-56, an even rarer unlensed object at high-redshift identified by the South Pole Telescope survey. It was determined to be a uniquely dense proto-cluster, the core of which contains 14 individual dusty, star-forming galaxies. We apply a modified black-body to multi-band photometry in an effort to constrain dust temperatures, we estimate star formation rates using three different tracers, and determine stellar, gas, and dynamical masses for the individual galaxies as well as consider them in the context of the greater proto-cluster. Finally in Chapter 4 we delve into updating an integral component of the cold-readout electronics critical to increasing the sensitivity of observations. We discuss the design considerations, fabrication techniques and challenges, and device assembly for planar lithographed superconducting capacitor-inductor resonator pairs. This work was initially done with the Polarbear-2 receiver in mind (another cosmic microwave background polarimetry experiment). However, modified designs have since been implemented in next-generation South Pole Telescope receivers as well. Each chapter contains its own conclusions, leaving Chapter 5 to conclude the thesis with future outlooks for the researched advanced here.