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Nov 6
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Caitlin M. Casey
University of California, Irvine
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"Mergers or not? A Submillimeter Perspective on Cosmic Star Formation" (host: S. Finkelstein)
Whether many of the Universe's stars are formed in galaxy mergers or quiescent, secularly evolving disk galaxies is fiercely debated. Whatever the formation mechanism, about half of all star formation activity is emitted in the infrared by dusty galaxies. Locally, dusty infrared galaxies are merger-dominated, but their origin is less clear at high-redshift. Observing the most luminous star-forming galaxies -- galaxies which are rare but produce huge numbers of stars very rapidly -- provides an important method of studying galaxy evolution and the stellar mass assembly of the early Universe. Infrared observations are uniquely useful since they probe star formation directly, as seen from dust-reprocessed emission of ultraviolet light from young stars.
I will describe some of the latest research surrounding infrared-luminous starburst galaxies, from low to high redshift, and present some of the conundrums of the field (from sample selection biases, observational limitations, to disagreements over galaxies' evolution). With a plethora of new observational tools becoming available in the infrared and sub-millimeter (e.g. Herschel, SCUBA-2 and ALMA, and eventually CCAT), distant galaxies will soon be studied in exquisite detail in both dust and gas, filling in gaps of information which cannot be answered by detailed studies of their obscured stellar emission. Future observations with 30m-class telescopes like the GMT will dramatically improve observations of stellar continuum and nebular line emission in dusty galaxies to the necessary depth, so that stars, dust and gas can be studied in tandem. Our long-term goal is to understand the triggering mechanisms for star formation episodes in extreme, ultraluminous starburst environments, how they relate to star formation in more common "Milky Way" type galaxies at high-redshift, and what the implications are for galaxy evolution at very early times.
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