Building Ancient Cosmic CitiesGalaxy Protoclusters are large overdense structures in the early Universe from which galaxy clusters gravitationally collapse. They represent an unique interface between the subjects of galaxy formation and cosmology, and a key laboratory to study both in their extreme conditions. A major part of my work has been pioneering the numerical modeling, observations, and physical inferences of protoclusters and their relations to both large and small scale astrophysics.
Dissecting The 3D UniverseExtragalactic Background Light in Broad Band Intensity Mapping. Most of the photons ever recorded by astronomical instruments are in the form of images—or broad-band intensity maps. Usually a large fraction of these photons are in the diffuse field, or pixels outside individual objects. They are often discarded during the process of background removal (by e.g., SExtractor), which is an unfortunately waste of information. I developed an angular cross correlation technique to recover the redshift of the diffuse extragalactic background light (EBL), and has potential to recover its spectral energy distribution (SED) with a spectral resolution much higher than the original bandwidth. Such a time and frequency dependent radiation output will provide a critical summary statistics of cosmological galaxy formation.
Clustering Redshift Estimation is a powerful technique to obtain distance distributions of extragalactic objects or photons using their angular fluctuations on the sky. Utilizing the fact that extragalactic objects are gravitationally clustered in the filamentary cosmic web, we can propagate information from a spatially 3D data set (the "reference" sample with RA, Dec, redshift available) to a 2D one (the "unknown"). This is achieved by a series of angular cross correlations. The applications include inferring the redshift distribution of photometrically selected galaxies, and deprojecting various cosmic intensity fields from 2D back to 3D.
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