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Hunting the First Galaxies with Gravitational Lensing
April 14, 201411:30 am – 12:30 pm (CDT)

Hunting the First Galaxies with Gravitational Lensing


Dan Coe (Space Telescope Science Institute)



Munnerlyn Astronomical Laboratory

College Station, Texas 77843

Event Details

The first galaxies are a frontier of extragalactic astronomy. How and when did they form, and how did they contribute to reionization? Answers to these questions require both census taking and detailed studies of individual galaxies. Hubble and Spitzer have revealed galaxies well into the epoch of reionization (z > 6). Gravitational lensing has enabled relatively efficient discovery of galaxies at the highest redshifts. The Cluster Lensing and Supernova survey with Hubble (CLASH) Multi-Cycle Treasury program revealed galaxies as distant as MACS0647-JD at z ~ 10.8 (420 Myr). Upcoming HST WFC3/IR grism spectroscopy should help confirm this z ~ 11 discovery, and deep Spitzer imaging will constrain the galaxy’s age, stellar mass, and rest-frame UV slope (beta). Searches for additional z ~ 10 candidates have so far revealed fewer than expected. This z ~ 10 deficit suggests more rapid buildup in galaxy numbers and cosmic star formation rate density during the first 600 million years than at later times. Improved statistics to confirm or controvert this deficit are forthcoming from the Frontier Fields program. The first two strongly lensed Hubble Frontier Fields images are now our deepest images of the universe to date, probing nJy sources. Dr. Coe will present predictions and early results from this program. He will also show expectations for future wide field space-based surveys with Euclid and WFIRST-AFTA. These programs will significantly advance our understanding of galaxy evolution in the first billion years while providing promising targets for more detailed study with JWST.

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