BEGIN:VCALENDAR
VERSION:2.0
CALSCALE:GREGORIAN
PRODID:UW-Madison-Physics-Events
BEGIN:VEVENT
SEQUENCE:0
UID:UW-Physics-Event-3473
DTSTART:20141016T193000Z
DTEND:20141016T203000Z
DTSTAMP:20260419T161323Z
LAST-MODIFIED:20140916T144056Z
LOCATION:5280 Chamberlin
SUMMARY:The Extragalactic Gamma-ray Background AND Searching for Satel
 lite Galaxies of the Milky Way in the Dark Energy Survey\, NPAC (Nucle
 ar/Particle/Astro/Cosmo) Forum\, Keith Bechtol\, University of Chicago
DESCRIPTION:Part 1: The extragalactic gamma-ray background (EGB) is ge
 nerated by the superposition of all extragalactic gamma-ray emissions 
 and therefore provides a window on both the demographics and evolution
  of non-thermal phenomena across cosmic time. A significant fraction o
 f the total EGB intensity has now been resolved into individual source
 s using the Fermi LAT\, and there is an emerging understanding of how 
 fainter members of the established extragalactic gamma-ray source clas
 ses can account for a majority of the residual approximately isotropic
  component of the gamma-ray sky\, called the isotropic gamma-ray backg
 round (IGRB). The latest measurement of the IGRB spectrum with the Fer
 mi LAT from 100 MeV to 820 GeV exhibits a high-energy cutoff feature c
 onsistent with the attenuation of high-energy gamma rays by pair-produ
 ction on the IR/optical/UV extragalactic background light. High-energy
  cosmic neutrinos will be essential to see beyond this gamma-ray horiz
 on to greater distances and higher energies.<br>
\n<br>
\nPart 2: Targ
 eted searches for indirect dark matter signals in the direction of Mil
 ky Way satellite galaxies provide some of the strongest current constr
 aints on the annihilation cross section of dark matter derived from ga
 mma-ray observations. Milky Way satellite galaxies have the advantages
  of low astrophysical backgrounds\, the ability to constrain the dark 
 matter abundance and distribution from the kinematics of member stars\
 , and the opportunity to combine observations of multiple satellites i
 n a joint-likelihood framework to enable more sensitive analyses. Acco
 rdingly\, the discovery of additional Milky Way satellites in wide-fie
 ld optical imaging surveys may provide substantial advances for indire
 ct dark matter searches. I will discuss a matched-filter maximum-likel
 ihood algorithm to search for and characterize ultra-faint galaxies in
  the ongoing Dark Energy Survey\, which will cover 5000 square degrees
  in the relatively less explored south Galactic cap.
URL:https://www.physics.wisc.edu/events/?id=3473
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