A newly released map shows our home galaxy in a new light. The eROSITA telescope has scanned the entire sky in X-rays, painting a colorful portrait that reveals large-scale structures and hundreds of thousands of previously unknown X-ray sources.
From its perch onboard the SRG spacecraft, the eROSITA X-ray telescope slowly sweeps the entire dome of the sky. The instrument rotates constantly, so that each region is viewed for between 150 and 200 seconds. Over 182 days, it manages to capture the disc of the Milky Way galaxy and its surrounds, peering four times deeper than the previous ROSAT survey.
The resulting image is stunning. The detected photons were color-coded to represent their energy levels; the red regions have the lowest energies, at 0.3 to 0.6 kiloelectronvolts (keV), green areas have energies between 0.6 and 1 keV, while blue represents 1 to 2.3 keV.
The dense dust and gas in the center of the galaxy absorbs the lower-energy X-ray photons, revealing the Milky Way disc in stark detail as a streak of blue. The green regions, swirling away from the center, represent hot gas being swept away from energetic events like supernovae.
The large yellow bubbles above and below the galactic plane show gigantic “X-ray chimneys” that appear to be pumping gas out of the central region into the outskirts. These could be left over from ancient periods of intense activity from the Milky Way’s central black hole.
The red tinge of the rest of the image is a bubble of diffuse, hot gas much closer to the solar system, which eROSITA had to peer through.
The bright spots and smudges dotted throughout are X-ray sources such as quasars and other active galactic nuclei. These are glowing thanks to huge amounts of dust and gas heating up as it falls into black holes. Other points may be magnetars, binary star systems, and supernova remnants.
All up, this eROSITA image has captured over a million X-ray sources. That’s twice as many as have previously been discovered.
And this is just the beginning. The SRG Observatory is now starting a second survey, and over the next three and a half years will produce another seven maps like this. Combining all of these together will allow astronomers to peer ever deeper into the cosmos.
Source: Max Planck Institute
