Galactic anatomy with gamma rays

February 01, 2015

The anatomy of the Milky Way as seen in gamma light is full of mysteries. For example, there are gigantic bubbles of unknown origin above and below the center of the Milky Way that emit a lot of this high-energy radiation. A new method for imaging, developed at the Max Planck Institute for Astrophysics, now divided the Galactic gamma-radiation into three fundamental components: radiation from point sources, radiation from reactions of energetic protons with dense cold gas clouds, and radiation from electrons scattering light in the thin, hot, Galactic gas. The anatomic insights gained unravel some Galactic mysteries. Thus, it appears that the gamma-ray bubbles are simply outflows of ordinary, hot gas from the central region of the Milky Way.

Fig 1: Gamma-ray data (left) and diffuse Galactic gamma-radiation calculated by D3PO (right). The Galactic disk is displayed horizontally, with the Galactic center in the middle of the image.
Fig 2: The gamma-ray sky at different stages of the data analysis: (a) The data of the Fermi satellite. D3PO denoised, deconvolved, and decomposed the data into (b) diffuse emission and (c) point sources. A further separation reveals the gamma-rays emitted by (d) hot, dilute clouds of gas and (e) cold, dense gas clouds, which closely resemble (f) the Galactic dust clouds from the Planck mission. (g) The sum of the two gamma components (d and e) explains around 90% of the total diffuse gamma-radiation.
Fig 3: Marco Selig after his doctorate examination, which he passed with honors at the Ludwig-Maximilians-Universität München.

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