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Testing Inflationary Cosmology with the BICEP1 and BICEP2 Experiments


Aikin, Randol Wallace (2013) Testing Inflationary Cosmology with the BICEP1 and BICEP2 Experiments. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/z9vx0df2.


Recent observations of the temperature anisotropies of the cosmic microwave background (CMB) favor an inflationary paradigm in which the scale factor of the universe inflated by many orders of magnitude at some very early time. Such a scenario would produce the observed large-scale isotropy and homogeneity of the universe, as well as the scale-invariant perturbations responsible for the observed (10 parts per million) anisotropies in the CMB. An inflationary epoch is also theorized to produce a background of gravitational waves (or tensor perturbations), the effects of which can be observed in the polarization of the CMB. The E-mode (or parity even) polarization of the CMB, which is produced by scalar perturbations, has now been measured with high significance. Con- trastingly, today the B-mode (or parity odd) polarization, which is sourced by tensor perturbations, has yet to be observed. A detection of the B-mode polarization of the CMB would provide strong evidence for an inflationary epoch early in the universe’s history.

In this work, we explore experimental techniques and analysis methods used to probe the B- mode polarization of the CMB. These experimental techniques have been used to build the Bicep2 telescope, which was deployed to the South Pole in 2009. After three years of observations, Bicep2 has acquired one of the deepest observations of the degree-scale polarization of the CMB to date. Similarly, this work describes analysis methods developed for the Bicep1 three-year data analysis, which includes the full data set acquired by Bicep1. This analysis has produced the tightest constraint on the B-mode polarization of the CMB to date, corresponding to a tensor-to-scalar ratio estimate of r = 0.04±0.32, or a Bayesian 95% credible interval of r < 0.70. These analysis methods, in addition to producing this new constraint, are directly applicable to future analyses of Bicep2 data. Taken together, the experimental techniques and analysis methods described herein promise to open a new observational window into the inflationary epoch and the initial conditions of our universe.

Item Type:Thesis (Dissertation (Ph.D.))
Subject Keywords:Cosmology, Polarization, CMB, Cosmic Microwave Background, Physics, Experiment
Degree Grantor:California Institute of Technology
Division:Physics, Mathematics and Astronomy
Major Option:Physics
Thesis Availability:Public (worldwide access)
Research Advisor(s):
  • Golwala, Sunil
Group:Astronomy Department
Thesis Committee:
  • Golwala, Sunil (chair)
  • Hirata, Christopher M.
  • Bock, James J.
  • Filippone, Bradley W.
Defense Date:24 May 2013
Non-Caltech Author Email:raikin (AT)
Funding AgencyGrant Number
National Science FoundationANT-0742818
Record Number:CaltechTHESIS:06072013-113004037
Persistent URL:
Default Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:7866
Deposited By: Randol Aikin
Deposited On:04 Nov 2013 20:28
Last Modified:26 Oct 2021 17:28

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