Yi-Kuan Chiang

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The cosmic infrared background (CIB) traces the aggregate dust emission from all galaxies, providing a powerful probe for precision astrophysics and cosmology. We measure its evolving spectrum by cross-correlating diffuse far-infrared photons from Planck, Herschel, and IRAS with SDSS/BOSS/eBOSS galaxies up to z=4. This tomographic CIB spectrum reveals a broad, mildly evolving dust temperature distribution. We constrain cosmic dust density, Omega_dust, finding it peaks at z~1.5 and declines at late times, suggesting significant dust destruction. We measure total infrared luminosity density to sub-10% precision, uncovering a highly dust-obscured census of cosmic star formation over 0 < z < 4. For the first time, we also detect cosmic CO and CII backgrounds without line confusion. This work highlights large-scale data fusion in survey astronomy, integrating 10^8 intensity voxels across a 50-fold frequency range and 3 × 10^6 reference redshifts via 10^6 cross-correlations.