Cosmic Infrared Background Tomography: Revealing the Full Spectrum with Thermal Dust, CO, and CII over 0 < z < 4

Yi-Kuan Chiang^1*

¹Institute of Astronomy and Astrophysics, Academia Sinica, Taipei, Taiwan

* Presenter:Yi-Kuan Chiang, email:ykchiang@asiaa.sinica.edu.tw

The cosmic infrared background (CIB) encompasses the aggregate dust emission from all galaxies in the Universe, making it a valuable probe for precision astrophysics and cosmology. To unlock CIB science, we measure its spectrum and redshift evolution by cross-correlating 11 far-infrared intensity maps from Planck, Herschel, and IRAS with reference galaxies in SDSS I-IV with spectroscopic redshifts up to z=4. Using this densely sampled CIB spectrum, we constrain the full distribution of cosmic dust temperature per epoch beyond a single temperature graybody and find the heating more intense at high redshifts. Using the total far-IR luminosity density, we probe the cosmic star formation over 90% of cosmic time in one shot. With low-frequency amplitudes, we constrain the cosmic dust mass budget, Omega_dust, and find it decreases at z<1, highlighting the need to destroy or expel dust into the circumgalactic medium. Using the excess on top of the precisely measured continuum, we present the first robust intensity mapping detections of the cosmic CO (9 lines) and [CII] line backgrounds. From low-J CO, we derive a cosmic molecular gas history Omega_H2. The CIB alone thus closes the loop of the baryon cycle of galaxies in turning gas into stars, along with the chemical enrichment through dust across cosmic history.

Keywords: Cosmic infrared background, Large-scale structure, Galaxy evolution, Cosmic dust, Observational cosmology