Dissecting and Reconstructing the Cosmic Infrared Background with Spaceborne Experiments

The utilization of several tracers of large-scale structure has led to important advancements in our understanding of the history of the Universe, in both characterizing cosmological initial conditions and late-time astrophysics. With the onset of dramatic changes in data volume and quality through existing and near-future experiments, methodologies that harness the information content in imaging and spectroscopic datasets while mitigating systematic effects will have larger impacts than ever before. In this thesis, we present a variety of analysis techniques for galaxy surveys of discrete objects and diffuse light measurements that are demonstrated on both synthetic and real datasets. In Chapter 2, we develop techniques for measurement of near-infrared extragalactic background light (EBL) anisotropies, focusing SPHEREx on imager data from the Cosmic Infrared Background ExpeRiment (CIBER). Through improvements in methodology and data quality, we present fluctuation measurements in Chapter 3 that are five to ten times more sensitive on several arcminute to degree scales than existing studies, with clear detection of diffuse anisotropies exceeding those from the Poisson noise of individual stars and galaxies. In Chapter 4, we present a new suite of empirically-based galaxy simulations which we use to examine the diversity of galaxies that will be observed withSPHEREx, NASA's upcoming MIDEX mission. We then develop and apply redshift estimation techniques to synthetic SPHEREx observations generated from these simulations, demonstrating the ability to measure the distances to several hundred million galaxies over the full sky. In Chapter 5, we describe a formalism for modeling point-like and diffuse signals in astronomical images, which can be used for robust photometry in the presence of diffuse contaminants, extraction of diffuse signals in the presence of point source contaminants, and more general component separation. In Chapter 6 we apply this modeling framework to Herschel-SPIRE observations of galaxy cluster RX J1347.5-1145, measuring the diffuse thermal Sunyaev-Zel'dovich (tSZ) effect at high significance and using relativistic corrections of the tSZ spectrum to constrain the intra-cluster medium temperature, for which we find consistent estimates with independent X-ray measurements.