ABSTRACT:
Cosmological observations have determined the abundance and large-scale structure of dark matter with unprecedented precision, but the nature of dark matter remains a mystery. I will review the overwhelming evidence for cosmological dark matter. For the leading weakly-interacting cold dark matter particle candidate, its thermal production in the early universe predicts a canonical annihilation rate to potentially observable standard particles and gamma-rays today. I will discuss several observatories' methods of trying to detect or constrain dark matter. The center of our Milky Way Galaxy has been known to be the most luminous source of gamma-ray photons from dark matter annihilation. I will present our recent work which shows that observations by the Fermi Gamma-ray Space Telescope reveal that the Galactic Center has a source with large luminosity and high statistical significance that is consistent in several ways with extended emission from dark matter annihilation, though astrophysical sources could mimic this signal. I will discuss the details of the observation, its interpretations, implications, and the potential future resolution of the nature of this source as a signal of dark matter or not.