Speaker
Description
Over the last seven years, Fermi-LAT observations have convincingly
found an excess in gamma-ray emission emanating from the center of the
Milky Way galaxy. The excess has three definitive properties: (1) it
has a hard spectrum that peaks at an energy of ~2 GeV, (2) it extends
from within 0.1 degrees to more than 10 degrees from Sgr A* with a
three-dimensional intensity that falls roughly as r^-2, (3) it is
approximately spherically symmetric. Several models for this excess
have been formulated, including the collective emission from a
population of individually dim gamma-ray pulsars, outbursts of
cosmic-ray electrons from the central molecular zone, or potentially
even dark matter annihilation. In this talk, I will discuss the
arguments for and against each model, focusing specifically on
constraints from multi-wavelength observations. Additionally, I will
discuss the future observations that are critical for understanding
the origin of the gamma-ray excess.
