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To the Horizon and Beyond:Weak Lensing of the CMB and Binary Inspirals into Horizonless Objects


Kesden, Michael Henry (2005) To the Horizon and Beyond:Weak Lensing of the CMB and Binary Inspirals into Horizonless Objects. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/BQMR-4C14.


This thesis examines two predictions of general relativity: weak lensing and gravitational waves. The cosmic microwave background (CMB) is gravitationally lensed by the large-scale structure between the observer and the last-scattering surface. This weak lensing induces non-Gaussian correlations that can be used to construct estimators for the deflection field. The error and bias of these estimators are derived and used to analyze the viability of lensing reconstruction for future CMB experiments.

Weak lensing also affects the one-point probability distribution function of the CMB. The skewness and kurtosis induced by lensing and the Sunayev-Zel'dovich (SZ) effect are calculated as functions of the angular smoothing scale of the map. While these functions offer the advantage of easy computability, only the skewness from lensing-SZ correlations can potentially be detected, even in the limit of the largest amplitude fluctuations allowed by observation.

Lensing estimators are also essential to constrain inflation, the favored explanation for large-scale isotropy and the origin of primordial perturbations. B-mode polarization is considered to be a "smoking-gun" signature of inflation, and lensing estimators can be used to recover primordial B-modes from lensing-induced contamination. The ability of future CMB experiments to constrain inflation is assessed as functions of survey size and instrumental sensitivity.

A final application of lensing estimators is to constrain a possible cutoff in primordial density perturbations on near-horizon scales. The paucity of independent modes on such scales limits the statistical certainty of such a constraint. Measurements of the deflection field can be used to constrain at the 3-sigma level the existence of a cutoff large enough to account for current CMB observations.

A final chapter of this thesis considers an independent topic: the gravitational-wave (GW) signature of a binary inspiral into a horizonless object. If the supermassive objects at galactic centers lack the horizons of traditional black holes, inspiraling objects could emit GWs after passing within their surfaces. The GWs produced by such an inspiral are calculated, revealing distinctive features potentially observable by future GW observatories.

Item Type:Thesis (Dissertation (Ph.D.))
Subject Keywords:binary inspirals; cosmic microwave background; gravitational waves; weak lensing
Degree Grantor:California Institute of Technology
Division:Physics, Mathematics and Astronomy
Major Option:Physics
Thesis Availability:Public (worldwide access)
Research Advisor(s):
  • Kamionkowski, Marc P.
Thesis Committee:
  • Kamionkowski, Marc P. (chair)
  • Readhead, Anthony C. S.
  • Phinney, E. Sterl
  • Wise, Mark B.
Defense Date:20 May 2005
Non-Caltech Author Email:kesden (AT)
Record Number:CaltechETD:etd-05232005-160004
Persistent URL:
Kesden, Michael Henry0000-0002-5987-1471
Default Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:1972
Deposited By: Imported from ETD-db
Deposited On:24 May 2005
Last Modified:05 Nov 2021 22:57

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