Line Intensity Mapping with the CO Mapping Array Pathfinder - Probing Two Key Epochs in Cosmic Evolution

California Institute Of Technology, Pasadena CA

Investigators

Abstract

The Universe began with a Big Bang 13.8 billion years ago. 400,000 years after the Big Bang the Universe had no stars or galaxies, but was filled with gas - mostly hydrogen atoms. Over the next few billion years these atoms formed themselves into the first stars, galaxies and groups of galaxies, eventually resulting in the kind of Universe we see around us today. We can't see the starlight from these first galaxies because at this time the hydrogen atoms between the galaxies acted as a kind of fog. Radio waves from carbon monoxide gas in the galaxies can pierce the fog. We have built a new kind of 'radio camera' and will use it to measure these radio waves and unveil the hidden galaxies. This is important because it will transform our understanding of the way stars and galaxies formed over cosmic time and help train the next generation of radio astronomers and instrumentalists designing other more powerful radio cameras. The COMAP team will communicate their results to the public in a variety of formats including a public lecture series, a local newspaper column, web pages, local science fairs, activities at the telescope (e.g. open house, tours and star-gazing parties) and an annual visit and tour for the United American Indian Involvement. The CO Mapping Array Pathfinder (COMAP) will open new windows on both the Epoch of Reionization (EoR) and the Epoch of Galaxy Assembly by using carbon monoxide (CO) lines to trace the evolution of star formation in galaxies through these two important epochs. COMAP is a pioneering instrument that exploits a novel technique called "Line Intensity Mapping" (LIM), which will provide a new way to study the properties and evolution of galaxies over cosmic time, using tracers such as CO, neutral hydrogen or ionized carbon. The first LIM auto-correlation detection is within reach and this proposal will put COMAP in a competitive position in this regard. COMAP Phase I comprises a 10.4-m telescope, located at the Owens Valley Radio Observatory (OVRO), equipped with a 19-pixel spectrometer array that will map a total of about 16 square degrees of sky in the frequency range 26-34 GHz, with spectral resolution of 2 MHz. In Phase I, COMAP is thus sensitive to CO(2-1) emission from the EoR and CO(1-0) emission from the epoch of galaxy assembly. The Phase I receiver has been commissioned and science observing began in June 2019. This award will be used to complete a 2-year observing campaign, analyze the data and publish the results. The analysis will focus on the CO(1-0) signal from z=2.4-3.4, which could be detected at high significance. 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.