Ivan Padilla (Case Western Reserve University)

Date: Tue. October 8th, 2024, 11:30 am-12:30 pm
Location: Rock 221 Foldy room

Microwave Cosmology at Large Angular Scales

The Cosmic Microwave Background (CMB), in both temperature and polarization, has provided precise measurements of the Dark Energy + Cold Dark Matter (LCDM) model of cosmology. Numerous ground-based, balloon-borne, and space experiments have extracted most of the available information from the CMB. However, two of the seven possible parameters remain poorly constrained: the tensor-to-scalar ratio ( r ), which parameterizes the amplitude of primordial gravitational waves expected if the Universe underwent early inflation, and Tau ($\tau$), the optical depth to the Epoch of Reionization, which is strongly dependent on the yet unknown mechanism that reionized neutral hydrogen. Improved polarized measurements at larger angular scales (>10 degrees) would significantly constrain both parameters.

Galactic foregrounds, both at high and low frequencies, pose a significant challenge at these scales. Emissions from synchrotron and Galactic dust are order-of-magnitudes brighter at large scales than at degree-angular-scales, and other possible components such as polarized Anomalous Microwave Emission (AME) still lurk. I will discuss the current constraints on polarized Galactic foregrounds, how allowable deviations from foreground models affect cosmological parameter recovery, and the state-of-the-art analytical and experimental strategies to mitigate them.