In this thesis, I use data from large scale structure surveys to explore both galaxy evolution and cosmology. My thesis covers four distinct areas: galaxy spin alignments with large-scale structure filaments (Chapters 2 and 3); voids in the Lyman-α forest (Chapter 4); quasar evolution and the thermal Sunyaev-Zel’dovich effect (Chapter 5); and cross-correlations between unWISE infrared galaxies and the cosmic microwave background (Chapters 6 and 7).
Hierarchical structure formation imprints a characteristic alignment between large-scale filaments and dark matter halos: low-mass halos accrete perpendicular to the filaments and thus acquire spin along the filament, whereas high-mass halos grow by mergers and thus acquire spin perpendicular to the filament. These spin alignments lead to correlations between galaxy shapes and large-scale structure, a major systematic for weak lensing surveys. I study the prospects for detecting this signal at z ∼ 2.5 using filaments measured in the Lyman-α forest, and also present an upper limit on galaxy spin-filament alignments at z ∼ 0.1 with the MaNGA survey of galaxy kinematics.
Voids are a powerful probe of dark energy, modified gravity, and neutrino mass. I present the highest-redshift detection of voids (z ∼ 2.5) and first detection of voids in the Lyman-α forest. I show that these voids are > 5σ underdense in coeval spectroscopic galaxies, and characterize their stacked profile and distribution of sizes.
The thermal Sunyaev-Zel’dovich effect is a powerful probe of hot halo gas. I study the physical origin of the tSZ-quasar cross-correlation. On large scales, it probes the bias of the hot halo gas, and future tSZ-quasar cross-correlation studies will constrain the amplitude of the tSZ signal across all halos at 0 < z < 2. On small scales, the tSZ signal scales as M^5/3, and is thus sensitive to the distribution of quasar host halos. tSZ cross-correlations from the DESI survey should place interesting constraints on quasar models that otherwise match quasar clustering and luminosity function data. Moreover, because DESI is fainter than previous quasar samples, the tSZ signal should be dominated by contributions from the host halo virialization rather than from energy injection by AGN feedback, which scales with the quasars’ luminosity.
Chapters 6 and 7 explore the cosmological constraining power of infrared galaxies from the unWISE catalog in tandem with cosmic microwave background observations. In Chapter 7, I measure the cross-correlation between unWISE infrared galaxies at z < 2 and Planck CMB lensing. With signal-to-noise of 80, this is the highest-significance detection of CMB lensing cross-correlations thus far, offering the potential for percent-level constraints on the amplitude of matter clustering. In Chapter 7, I describe the measurement and systematics tests; the most significant systematic is the uncertain redshift distribution of the unWISE galaxies, which I measure using cross-correlations with SDSS spectroscopic galaxies and quasars. In Chapter 7 I measure the cross-correlation between unWISE galaxies and CMB temperature on large scales from the integrated Sachs-Wolfe effect. This is a 3 to 4σ detection of dark energy and holds promise for constraining modified gravity models throughout the dark energy dominated epoch.