The universe as seen with the eROSITA X-ray telescope
As eROSITA scans the sky, the energy of the collected photons is measured with an accuracy ranging from 2% – 6%.
To generate this image, in which the whole sky is projected onto an ellipse (so-called Aitoff projection) with the center of the Milky Way in the middle and the body of our Galaxy running horizontally, photons have been color-coded according to their energy (red for energies 0.3-0.6 keV, green for 0.6-1 keV, blue for 1-2.3 keV).
The red diffuse glow away from the galactic plane is the emission of the hot gas in the vicinity of the Solar System (the Local Bubble). Along the plane itself, dust and gas absorb the lowest energy X-ray photons, so that only high-energy emitting sources can be seen, and their color appears blue in the image.
The hotter gas close to the Galactic center, shown in green and yellow, carries imprinted the history of the most energetic processes in the life of the Milky Way, such as supernova explosions, driving fountains of gas out of the plane, and, possibly, past outburst from the now dormant supermassive black hole in the center of the Milky Way.
Piercing through this turbulent, hot diffuse medium, are hundreds of thousands of X-ray sources, which appear mostly white in the image, and uniformly distributed over the sky. Among them, distant active galactic nuclei are visible as point sources, while clusters of galaxies reveal themselves as extended X-ray nebulosities.
In total, about one million X-ray sources have been detected in this image.
Image credit: Jeremy Sanders, Hermann Brunner & the eSASS team / Max Planck Institute for Extraterrestrial Physics / Eugene Churazov & Marat Gilfanov, IKI.