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NRAO/Socorro Colloquium Series

Meng Su

CfA

Diffuse Gamma-ray Emission from the Inner Galaxy: Bubbles, Jets, and Dark Matter Annihilation

Using data from the Fermi Gamma-ray Space Telescope, we have discovered two gigantic gamma-ray emitting bubble structures in our Milky Way (known as the Fermi bubbles), extending ~50 degrees above and below the Galactic center with a width of ~40 degrees in longitude. The gamma-ray emission associated with these bubbles has a significantly harder spectrum than the inverse Compton emission from known cosmic ray electrons in the Galactic disk, or the gamma-rays produced by decay of pions from proton-ISM collisions. The bubbles are spatially correlated with the hard-spectrum microwave excess known as the WMAP haze; we also found features in the ROSAT soft X-ray maps which line up with the edges of the bubbles (confirmed by XMM-Newton observations). The Fermi bubbles are most likely created by some large episode of energy injection in the Galactic center. Furthermore, we have recently identified a gamma-ray cocoon feature within the southern bubble, with a jet-like feature along the cocoon’s axis of symmetry, and another directly opposite the Galactic center in the north. If confirmed, these jets are the first resolved gamma-ray jets ever seen. In addition to these components, there is evidence for line emission at E>100 GeV in the inner Galaxy.  If confirmed, this line emission may be a sign of dark matter annihilation.                                      


March 15, 2013
11:00 am

Array Operations Center Auditorium

All NRAO employees are invited to attend via video, available in Charlottesville Room 230, Green Bank Room 137 and Tucson N525.

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