Toward Improved CMB Foreground Measurements: Laboratory Characterization of Multi-Chroic Microwave Kinetic Inductance Detectors and High-Resolution Observations of Anomalous Microwave Emission 220 views

Precision measurements of the cosmic microwave background (CMB) provide a powerful probe of fundamental physics and cosmology, but are limited by both instrumental sensitivity and contamination by astrophysical foregrounds. This dissertation addresses these challenges through both detector development and radio observations, to support enhanced measurement of dust-related CMB foregrounds. First, I present the laboratory characterization of prototype microwave kinetic inductance detectors (MKIDs) developed for CMB polarimetry. MKIDs are superconducting resonators that enable sensitive photon detection and naturally support large (kilopixel), frequency-multiplexed detector arrays. I characterize the performance of a novel dichroic architecture designed for simultaneous polarimetry near the peaks of the CMB and thermal dust SEDs, to enhance component separation. Optical testing demonstrates that the prototypes are optically live and reasonably sensitive in spite of TLS effects, motivating further development. Second, I describe the development and cryogenic testing of a pixel-to-frequency mapping module designed to support scalable characterization of large MKID arrays. The design minimizes cryogenic wiring, and thus thermal loading on the test stage. Third, I present high-resolution observations of anomalous microwave emission (AME), a dust-related CMB foreground. Using arcminute-resolution total intensity mapping with the Green Bank Telescope (GBT) in the Ku-band (13~GHz), I investigate AME associated with a Galactic star-forming region. The global SED is consistent with spinning dust emission. I identify two sources of excess Ku-band emission consistent with spinning dust--the first is spatially coincident with peak dust radiance and the second with peak PAH abundance. If these regions are, in fact, spinning dust emission in two different environments, this study is a resolved example of why low-resolution all-sky studies struggle to identify a single best tracer of AME. Together, these projects address complementary aspects of a single measurement challenge by establishing experimental constraints on both detector performance and dust-related microwave foregrounds. The results presented here contribute empirical context for future work on detector design and foreground modeling in CMB experiments.

PHD (Doctor of Philosophy)

Microwave Kinetic Inductance Detector (MKID); Anomalous Microwave Emission (AME); Cosmic Microwave Background (CMB); CMB Foregrounds; CMB Instrumentation; Green Bank Telescope (GBT); Spinning Dust Emission

English

2026-07-31