Fermi Bubble: Giant Gamma-Ray Bubbles in the Milky Way

Conference paper
Part of the Astrophysics and Space Science Proceedings book series (ASSSP, volume 34)


Data from the Fermi-LAT reveal two gigantic gamma-ray emitting bubble structures (known as the Fermibubbles), extending∼​​​​ 50 above and below the Galactic center symmetric about the Galactic plane, with a width of∼​​ 40 in longitude. The gamma-ray emission associated with these bubbles has a significantly harder spectrum \((\mathit{dN}/\mathit{dE} \sim {E}^{-2})\) 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. The bubbles are spatially correlated with the hard-spectrum microwave excess known as the WMAPhaze; the edges of the bubbles also line up with features in the ROSATsoft X-ray maps at 1.5–2keV. The Fermibubble is 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∼10Myr. 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 high-latitude cosmic ray population.


Wilkinson Microwave Anisotropy Probe Galactic Plane Dark Matter Annihilation Starburst Galaxy Hard Spectrum 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.



The author acknowledges Douglas Finkbeiner and Tracy Slatyer for their wonderful collaborations on the discovery paper of the Fermi bubbles. Most of the materials in this chapter is based on this paper. The author also acknowledges stimulating conversations with Roland Crocker, Greg Dobler, Martin Elvis, Jonathan Grindlay, Fulai Guo, Christine Jones, Avi Loeb, Sera Markoff, Igor Moskalenko, Ramesh Narayan, Aneta Siemiginowska, Andrew Strong, and Feng Yuan. The author would also like to warmly thank Olaf Reimer and Diego Torres for organizing the 2nd Sant Cugat Forum on Astrophysics, “2012: Cosmic-ray phenomenology in star-forming environments”, and their great effort to make the publication of this conference book possible.


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© Springer-Verlag Berlin Heidelberg 2013

Authors and Affiliations

  1. 1.Institute for Theory and ComputationHarvard-Smithsonian Center for AstrophysicsCambridgeUSA

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