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Physics Colloquium: James Aguirre (University of Pennsylvania), Title: The Universe in (Low-res) 4-D: How “Line Intensity Mapping” Probes Cosmic Evolution

Event Type
Department of Physics
Loomis Lab 141 and via Zoom
wifi event
Nov 9, 2022   4:00 pm   5:00pm
James Aguirre (University of Pennsylvania)
Kelly Darr
Originating Calendar
Physics - Colloquium

I describe a new method of measuring the clustering of matter and evolution of galaxies in the universe by making relatively low resolution maps of emission lines in the far-infrared and radio which is complementary to traditional approaches using optical and near-infrared surveys of galaxies.  I particular, I will describe two experiments, HERA and TIM, designed to measure the accretion of matter into galaxies and the formation of stars at two crucial epochs in the Universe’s history: at the birth of galaxies and at the peak of cosmic star formation.  The Hydrogen Epoch of Reionization Array (HERA) is a radio interferometer which uses the “21 cm” line of neutral hydrogen to measure the state of the intergalactic medium (IGM) from about 150 Myr to 1 Gyr after the Big Bang, will allow us to see the large-scale context of the first galaxies forming during this epoch (as recently revealed, for example, by the James Webb Space Telescope).  Recent results from radio measurements during this epoch have suggested anomalous behavior of the IGM which might be indicative of new physics.  HERA’s current observing season may be able to confirm or refute this detection; our most recent results have already shed light on the formation of the first accreting stellar-mass black holes and the heating of the IGM at early times.  The Terahertz Intensity Mapper (TIM) is a balloon-borne far-infrared spectrometer led at UIUC which will measure the ionized carbon fine-structure line in the most prodigiously star-forming galaxies at the midpoint of the universe’s life.  Combined with other measurements, TIM will trace the star formation history during this period and allow us to better understand the complex relation between the growth of large-scale structure and the formation of stars and supermassive black holes in galaxies.

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