Colloquium

Excess of Diffuse Gamma-ray Emission from the Inner Galaxy: Bubbles, Dark Matter, and the Future

Astronomers have been studying our home galaxy for centuries, yet we still find it full of surprises. I will first talk about the discovery of a pair of gigantic bubbles in the Milky Way using data from the Fermi Gamma-ray Space Telescope. This so-called "Fermi bubble" structure, extending to ~50 degrees above and below the Galactic center, could be evidence for past accretion activities of the central supermassive black hole. Then I'll summarize the current status of dark matter search with Fermi data from the Galactic center, with the focus on the earlier claimed gamma-ray line at 130 GeV and the recent evidence of a mysterious gamma-ray excess peaked at ~GeV. I will end up with a discussion of future gamma-ray space missions, in particular a mission concept of a dedicated smalll satellite mapping the sky from 10 MeV to 1 GeV. With much improved PSF and the capability of polarization measurement for the first time in this crucial energy range, this mission named PANGU will enhance our capability to search for dark matter annihilation signal, besides many other science goals it could potentially achieve.

Followed by wine and cheese in Pupin 1402.

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