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Astronomy Seminar Series artwork
September 25, 202311:30 am – 12:30 pm (CDT)

Into the Dusty Universe with ALMA and JWST


Jed McKinney (University of Texas, Austin)


Justin Spilker



Mitchell Institute for Fundamental Physics & Astronomy

College Station, Texas 77843

Event Details

Most of star-formation over the last 11 Billion years has happened within thick veils of dust, and in turn, dust shapes star-formation inside galaxies. Dust also absorbs and scatters light which can make optical probes of gas conditions difficult to measure, and hides very distant galaxies from even the most sensitive space telescopes. As a result, the inner workings of dust-obscured star-formation are mysterious for lack of empirical constraints and furthermore our census of dust at cosmic dawn is incomplete. In this talk I will focus on two related questions: (1) How prevalent is dust in the first ~1 billion years of the Universe?, and (2) What are the properties of dust in early galaxies and how do they compare to galaxies today? First I will introduce the SCUBADive project: a multi-wavelength effort to count and classify dusty star-forming galaxies in the COSMOS-Web survey. COSMOS-Web is the largest Cycle 1 JWST GO program, and its wide field NIRCam coverage makes it ideal for constraining the volume densities of rare galaxy populations. We use all publicly-available archival ALMA data over COSMOS-Web to localize far-infrared emission on JWST scales and find dusty galaxies beyond z>4. Next, I will introduce multiple programs using ALMA and JWST designed to measure the physical properties of dust grains at high-redshift. Combining far-infrared emission lines with mid-infrared features enables direct measures of the charge, size and the photoelectric heating efficiency of grains — key quantities that can regulate star-forming gas. I will discuss how this unique collection of data unlocks the inner workings of dusty star-formation, and what that implies for the assembly of massive galaxies. Finally, I will comment on next steps needed to fully understand dust-obscured star-formation which motivate a future cryogenically-cooled far-infrared space telescope.

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