ORCID
https://orcid.org/0009-0001-2732-8431
Subject Area
Astronomy/Astrophysics, Physics
Abstract
This dissertation investigates the evolution of cosmic expansion across a wide redshift ($z$) range by combining measurements from quasars \& galaxies in the distant universe $(z > 0.8)$ with those obtained from stripped-core collapse supernovae observations from the nearby universe $(z < 0.1)$. Using the DESI spectroscopic survey, we analyze large-scale clustering from quasars over $0.8 < z < 2.1$ and emission line galaxies over $0.8 < z < 1.6$, contributing to DESI DR2 BAO and full-shape measurements of cosmic expansion and structure growth. Combined with BBN in flat $\Lambda$CDM, DESI DR2 BAO gives $H_0 = 68.51 \pm 0.58$ km s$^{-1}$ Mpc$^{-1}$, while combinations of DESI BAO with CMB and supernova data show a preference for evolving dark energy, with representative constraints such as $w_0 = -0.752 \pm 0.057$ and $w_a = -0.86^{+0.23}_{-0.20}$ for DESI+CMB+DESY5. Using the ROTSE-III Supernova Survey and the expanding photosphere method (EPM), we measure distances to a sample of six supernovae for which the thermal phase can be clearly identified. This analysis focuses on testing whether reliable EPM distances can be obtained for this population. The resulting distances will eventually be compared with independent estimates from the literature. Establishing consistency with these external measurements represents an important step toward applying this methodology to larger samples, with the eventual goal of using ROTSE supernova distances to provide an independent measurement of the local Hubble constant.
Degree Date
Summer 8-4-2026
Document Type
Dissertation
Degree Name
Ph.D.
Department
Physics
Advisor
Robert Kehoe
Second Advisor
Joel Meyers
Third Advisor
Heidi Wu
Fourth Advisor
James Lasker
Number of Pages
301
Format
Creative Commons License
This work is licensed under a Creative Commons Attribution-Noncommercial 4.0 License
Recommended Citation
Vaisakh, Rajeev, "Measuring Cosmic Expansion from Early to Late Times Using Quasars, Galaxies, & Local Supernovae" (2026). Physics Theses and Dissertations. 25.
https://scholar.smu.edu/hum_sci_physics_etds/25
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