Dartmouth Events

Physics and Astronomy Senior Honor Thesis - Nina Maksimova - Dartmouth College

Title: "Testing Alternatives to the Standard Cosmological Model Using the Cosmic Microwave Background"

Tuesday, June 2, 2015
3:00pm – 5:00pm
Wilder 202
Intended Audience(s): Public
Categories: Lectures & Seminars

Abstract: The cosmic microwave background blackbody spectrum is one of the most powerful tools available in observational cosmology and it is extraordinarily versatile in constraining and ruling out exotic new physics. In this work, we review three different applications of the CMB to cosmology. In the first section, the spectral distortion of the cosmic microwave background blackbody spectrum in a radially inhomogeneous spacetime, designed to exactly reproduce a Lambda-CDM expansion history along the past light cone, is shown to exceed the upper bound established by COBE-FIRAS by a factor of approximately 3700. This simple observational test helps uncover a slew of pathological features that lie hidden inside the past light cone, including a radially contracting phase at decoupling and, if followed to its logical extreme, a naked singularity at the radially inhomogeneous Big Bang. In the second section, we present an analysis of the logarithmic moments of the cosmic microwave background frequency spectrum based on the COBE-FIRAS dataset. These moments provide a model-independent description of the CMB spectrum and can be interpreted in terms of physical quantities representing departures from a pure blackbody. In the third and final section, we analyze the production of chiral gravitational waves in two models of gauge-flation and calculate the corresponding imprints on the CMB. With an eye to future generations of CMB experiments, we predict their ability to detect and differentiate between these, and other, potential models of inflation. 

For more information, contact:
Tressena Manning
603-646-2854

Events are free and open to the public unless otherwise noted.