Reconstructing the Sky with CMB Lensing methods
| cam.depositDate | 2022-05-27 | |
| cam.restriction | thesis_access_open | |
| cam.supervisor | Sherwin, Blake | |
| dc.contributor.author | Darwish, Omar | |
| dc.date.accessioned | 2022-05-30T09:59:13Z | |
| dc.date.available | 2022-05-30T09:59:13Z | |
| dc.date.submitted | 2021-11-21 | |
| dc.date.updated | 2022-05-27T08:48:42Z | |
| dc.description.abstract | Current and future high significance CMB lensing-galaxy cross-correlations will soon precisely probe the growth of structure and provide powerful tests for parameter tensions, non-Gaussianity, neutrino mass, and modifications to Λ−CDM and gravity. However, such cross-correlations are sensitive to CMB foreground contamination, and the resulting biases represent an important challenge for cosmological analyses. In this thesis we describe new CMB lensing cross-correlation measurements and a novel multi-frequency cleaning-based technique to mitigate foreground effects in lensing maps. In particular, we present a tSZ cleaned cross-spectrum between Atacama Cosmology Telescope lensing and BOSS galaxies using a modified version of the standard quadratic estimator that retains most of the signal-to-noise. To minimize lensing foreground biases, geometry-based methods that modify the form of the standard quadratic estimator have been developed as well. We discuss how to optimally combine these with multi-frequency cleaned data to mitigate the impact of foreground contamination while maintaining maximal significance. For a Simons Observatory-like experiment, we find that for the CMB lensing auto-spectrum it is possible to reduce the foreground induced bias by a large factor, compared to the standard quadratic estimator, at a modest noise cost. We find a similar result for a cross-correlation with an LSST-like sample, with a large reduction in bias at small noise cost. Finally, we turn to the three-dimensional large scale structure of the Universe probed by galaxy surveys. We show how we can reconstruct the large-scale density field from galaxy modes using CMB lensing-inspired methods and use this reconstruction to improve constraints on local primordial non-Gaussianity. | |
| dc.description.sponsorship | STFC-CDT | |
| dc.identifier.doi | 10.17863/CAM.85000 | |
| dc.identifier.uri | https://www.repository.cam.ac.uk/handle/1810/337590 | |
| dc.language.iso | eng | |
| dc.publisher.institution | University of Cambridge | |
| dc.rights | All Rights Reserved | |
| dc.rights.uri | https://www.rioxx.net/licenses/all-rights-reserved/ | |
| dc.subject | cosmology | |
| dc.subject | cmb | |
| dc.subject | cmb lensing | |
| dc.subject | large-scale structure | |
| dc.title | Reconstructing the Sky with CMB Lensing methods | |
| dc.type | Thesis | |
| dc.type.qualificationlevel | Doctoral | |
| pubs.funder-project-id | STFC (1956705) | |
| pubs.funder-project-id | Science and Technology Facilities Council (1956705) | |
| pubs.licence-display-name | Apollo Repository Deposit Licence Agreement | |
| pubs.licence-identifier | apollo-deposit-licence-2-1 | |
| rioxxterms.licenseref.uri | https://www.rioxx.net/licenses/all-rights-reserved/ | |
| rioxxterms.type | Thesis |
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