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Investigating Large Scale Anomalies of the Cosmic Microwave Background

O'Dwyer, Marcio
http://rave.ohiolink.edu/etdc/view?acc_num=case1568822013962258

Abstract Details

2020, Doctor of Philosophy, Case Western Reserve University, Physics.
The Cosmic Microwave Background (CMB) temperature anisotropies have been mapped with increasing precision in the last 30 years. Although the measurements have been found to be in excellent agreement with statistical predictions of ΛCDM, several large-scale features of CMB temperature were observed to be anomalous, with p-values in the per mille to per cent level. Among those features is the lack of correlation on the largest angles (S1/2 anomaly) and the lack of variance in the ecliptic north. Although well-established results, they remain unexplained. To test the hypothesis that these anomalies are merely statistical fluctuations, we explore simulations of CMB maps constrained by current temperature data. We look at the contribution of the integrated Sachs-Wolfe effect to S1/2 and show how correlations from early-time and late-time physical effects contribute to its value. In anticipation of future polarization experiments, we generate realizations of polarization maps and predict the distribution of the hemispherical variance in polarization, considering different sky-coverage scenarios. We find that the low northern-hemisphere variance seen in temperature is not expected in polarization. We also study how the variance of polarization depends on current measurements of ΛCDM parameters and find that it is noticeably sensitive to present uncertainties in the reionization optical depth (τ). We explore how current improvements in the measurement of τ result in a tighter constraint on polarization-variance expectations, and how future τ measurements can further reduce the uncertainty in the polarization-variance distribution, thus improving our ability to test for the variance anomaly with upcoming polarization data.
Glenn Starkman (Advisor)
Craig Copi (Committee Member)
John Ruhl (Committee Member)
Stacy McGaugh (Committee Member)
128 p.
Astrophysics; Physics; Theoretical Physics
astrophysics; cosmology; cmb; cosmic microwave background; statistics; statistical anomaly; computational methods; statistical methods;

Recommended Citations

Citations

  • O'Dwyer, M. (2020). Investigating Large Scale Anomalies of the Cosmic Microwave Background [Doctoral dissertation, Case Western Reserve University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=case1568822013962258

    APA Style (7th edition)

  • O'Dwyer, Marcio. Investigating Large Scale Anomalies of the Cosmic Microwave Background. 2020. Case Western Reserve University, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=case1568822013962258.

    MLA Style (8th edition)

  • O'Dwyer, Marcio. "Investigating Large Scale Anomalies of the Cosmic Microwave Background." Doctoral dissertation, Case Western Reserve University, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=case1568822013962258

    Chicago Manual of Style (17th edition)

case1568822013962258
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© 2019, all rights reserved.
This open access ETD is published by Case Western Reserve University School of Graduate Studies and OhioLINK.