University of Illinois Urbana-Champaign

CMB lensing measurements with two years of data from the SPT-3G survey

Daley, Cail

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DALEY-DISSERTATION-2024.pdf

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https://hdl.handle.net/2142/127134

Description

Title
CMB lensing measurements with two years of data from the SPT-3G survey
Author(s)
Daley, Cail
Issue Date
2024-08-05
Director of Research (if dissertation) or Advisor (if thesis)
Holder, Gil
Doctoral Committee Chair(s)
Holder, Gil
Committee Member(s)
  • Fields, Brian
  • Filippini, Jeff
  • Ricker, Paul
Department of Study
Astronomy
Discipline
Astronomy
Degree Granting Institution
University of Illinois at Urbana-Champaign
Degree Name
Ph.D.
Degree Level
Dissertation
Keyword(s)
  • CMB
  • cosmology
  • gravitational lensing
  • South Pole Telescope
Abstract
The South Pole Telescope (SPT) is a 10 meter offset Gregorian telescope designed to observe the Cosmic Microwave Background (CMB) and astrophysical foregrounds at millimeter wavelengths. Radiation from the CMB is gravitationally lensed by large scale structure as it travels through the cosmos, complicating the analysis of the primordial CMB but also embedding information about the evolution and structure of the universe at more recent times. Measurements of the lensing potential can be used to constrain cosmological parameters (e.g. H₀, Ω_m, σ₈, and the sum of neutrino masses) and to remove lensing contamination from CMB B-mode polarization maps in the search for primordial gravitational waves. The SPT-3G experiment surveys 1500 deg² of the southern sky with ∼1′ angular resolution, allowing for high signal-to-noise measurements of the lensing potential out to sub-degree scales that can probe the nonlinear regime of the lensing power spectrum. In this thesis I present CMB lensing measurements made with data from the 2019 and 2020 observing seasons of the SPT-3G experiment. With per-pixel noise levels that are a factor of 3-4 lower than recent Planck and Atacama Cosmology Telescope lensing measurements, the SPT-3G lensing maps are the deepest CMB lensing maps ever made. While the analysis is ongoing, preliminary results indicate that we will measure the lensing power spectrum with a combined signal-to-noise of nearly 40σ, resulting in a 2-3% constraint on the amplitude of the lensing power spectrum A_ϕ. We expect to measure the Hubble constant H₀ to similar precision as other state of the art CMB lensing measurements, and expect to place the tightest CMB lensing constraints to date on the structure growth parameter S₈. The SPT-3G lensing maps will also be used to delens CMB polarization maps in the search for primordial gravitational waves in collaboration with BICEP/Keck, and will be excellent for cross-correlations especially given the high signal to noise of the polarization-based reconstruction that is robust to foreground contamination.
Graduation Semester
2024-12
Type of Resource
Thesis
Handle URL
https://hdl.handle.net/2142/127134
Copyright and License Information
Copyright 2024 Cail Daley

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Graduate Theses and Dissertations at Illinois