Oral Presentation

Full-sky Density Reconstruction in 2D and 3D

Author(s): Yi-Kuan Chiang (ASIAA)

Presenter: Yi-Kuan Chiang (ASIAA)

I will introduce an exciting new technique to optimally combine full-sky photometric surveys, such as WISE and SPHEREx, with large spectroscopic surveys including SDSS, BOSS, eBOSS, and DESI, to reconstruct the extragalactic density field. As a first demonstration (Chiang 2023, arXiv:2306.03926), we created a 2D projected map of large-scale structure (LSS) by extracting extragalactic fluctuations embedded in the 100 μm cosmic infrared background (CIB), using tomographic cross-correlations between over 600 million WISE galaxies and 3 million spectroscopic redshifts. The reconstructed field reproduces all high-dimensional tomographic two-point statistics of the CIB and spans the largest sky coverage of any LSS reconstruction to date. This all-purpose density field supports a wide range of cosmological and astrophysical applications, including full-sky searches for clusters and protoclusters. The method is readily extendable to higher redshifts. We aim to develop a 3D reconstruction by combining SPHEREx templates with DESI spectroscopy, reaching percent-level redshift precision to z=3, across a major portion of the observable universe.