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

Daley, Cail

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

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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