UC Davis

In this dissertation, I used early-type galaxies (ETGs) at intermediate redshifts (0.25 < ? < 0.75) to study both galaxy evolution and cosmology. I assembled a novel sample of 180 galaxies with integral field unit (IFU) data within this redshift range. Utilizing the extracted kinematic maps and photometric data, I measured the structural, kinematic, and stellar population properties of these galaxies. By comparing this sample with a subset of ETGs from the MaNGA survey, I demonstrated that the degree of rotational support in ETGs has decreased at lower redshifts. Furthermore, I investigated the discrepancies between observational results from lensing studies and predictions from cosmological simulations concerning the evolution of the total density slope of ETGs, which present conflicting views. Using Jeans anisotropic modeling, I modeled the observed resolved kinematics and measured the total density slope of this sample. My findings suggest that the slope in the ? − ? plane is generally negative, indicating an increase in the total density slope with decreasing redshift. However, due to the high level of uncertainty, I cannot conclusively dismiss the possibility of a zero or positive slope. In addition to studying these non-lensing ETGs, I also worked with ETGs which act as strong gravitational lenses, to measure the Hubble constant using the time-delay cosmography method. A crucial factor in accurately measuring the Hubble constant is the stellar kinematics of the lensing galaxies, which is challenging to measure due to the spatial blending of light caused by atmospheric seeing in ground-based telescopes. To address this, I developed a forward modeling method to extract high signal-to-noise ratio (SNR) one-dimensional spectra, enabling reliable kinematic measurements. The results presented in this dissertation contribute to our understanding of galaxy evolution and provide insights that could help resolve the Hubble tension, i.e., the discrepancy between independent inferences of the current expansion rate of the Universe. By improving our knowledge of ETG properties across redshifts and refining methods to measure the Hubble constant, this work advances our comprehension of the fundamental processes governing the Universe.