Speaker
Dr
Meng Su Su
(MIT)
Description
Based on 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 (dN/dE ~ E^(−2)) 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. There is no
significant difference in the spectrum or gamma-ray luminosity between the north
and south bubbles. 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 at 1.5 − 2 keV which line up with the edges of the bubbles. The
Fermi bubbles are most likely created by some large episode of energy injection in
the Galactic center, such as past accretion events onto the central massive black
hole, or a nuclear starburst in the last ~10 Myr. Study of the origin and evolution
of the bubbles also has the potential to improve our understanding of recent
energetic events in the inner Galaxy and the Galactic cosmic ray acceleration.
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.
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I will discuss the galactic jet in our milky way
Primary author
Dr
Meng Su Su
(MIT)
