University of Maryland
Atlantic Building, Room 2400
4:30 PM Monday, November 5, 2018
Coffee, Tea & Snacks 4:15-4:30 PM

Justin Finke
Space Science division, Naval Research Laboratory
The gamma-ray determination of the Universe's star formation history

The light emitted by all galaxies over the history of the Universe produces the extragalactic background light (EBL) at ultraviolet through the optical and into the infrared. Gamma rays emitted at cosmic distances are absorbed by the EBL photons, producing electron positron pairs, leaving an imprint on the gamma-ray spectra of distance sources. I discuss using the Fermi Large Area Telescope (LAT) to measure the absorption features in the gamma-ray spectra of a large sample of active galactic nuclei and reconstruct the evolution of the EBL. This allows for the reconstruction of the star formation history of the Universe throughout cosmic time with results and accuracy comparable to galaxy surveys. Gamma-ray upper limits on the EBL at the epoch of re-ionization suggests that the upcoming James Webb Space Telescope will resolve most of the faint galaxies at this epoch.

Sponsored by: Department of Physics and the Institute for Physical Science and Technology, University of Maryland. For information call Victoria at (301) 405-4811 or go to the UMD Space Physics group seminar web site.

There is free parking after 4:00 PM in lot B (the big parking garage across the street from the ATL building). There are a limited number of spaces in lot Q next to the new ATL wing with free parking after 4PM even when there is a basketball game on campus.