A deep and wide-area census of infrared-luminous galaxies in the high-redshift Universe

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Understanding how galaxies assemble their stars and central black holes is a crucial part of understanding our own cosmic origins - how our Milky Way, our solar system, and ultimately us, came to be. Moreover, a thorough understanding of how galaxies are built up allows us to use galaxies themselves as sensitive probes of the mysterious dark matter and dark energy that dominate the evolution of the universe. After intensive work by scientists using NSF facilities, we now know that some of the most important phases of galaxy assembly occur during the first half of the history of the universe, in moderately luminous galaxies that have, until recently, been difficult to detect as they appear faint on the sky. This project will use cutting-edge NSF and NASA facilities to investigate the nature of these moderately luminous, distant galaxies, and determine how their properties can be used to understand how galaxies like our own Milky Way formed. This project will also enable important work by other astronomers, by producing data that can be used for a wide range of investigations. Educational visualizations and lesson plans, made in collaboration with K-12 teachers, will contribute to STEM education.Obscured AGN and star formation are fundamental to galaxy assembly across the history of the Universe. Of particular importance are the moderately luminous systems - those with log LIR(Lsun) ~ 10-12 - as this is where the majority of black hole mass assembly takes place, and where the main sequence of star formation lies. There remain however critical open questions about obscured systems at z0.5 - what triggers them, what quenches them, and how their role depends on environment. This project will advance our understanding of how moderately luminous systems contribute to galaxy assembly at z1 by creating new, extremely deep ultraviolet through far-infrared catalogs across the 38 deg2 of the four DES/LSST Deep Drilling fields (DDFs), and then using these catalogs to study the evolution of high-redshift infrared-luminous galaxies in unprecedented detail. The science goals are: (1) quantify the evolution of the infrared galaxy luminosity function, simultaneously as functions of redshift, power source and environment, over 1 z 3 and log LIR(Lsun) ~ 9 - 12.2 (2) perform the first direct measurement of the bright end of the obscured AGN LF at z 2, without extrapolation from optically selected populations, and (3) measure the number density of massive quiescent galaxies at z4, to constrain AGN host evolution and stellar mass buildup at this epoch. The full catalogs across all of the DDFs will also be released to the community. This project will also develop interactive, 3D visualizations for use with both undergraduate and high school students. In conjunction with the Virginia Tech 'PhysTEC' program, the investigators will work directly with K-12 teachers to construct lesson plans and tutorials, which will be freely available to the community.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.