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Today, a new paper was published in Nature based on @eROSITA_SRG all-sky survey data. We found large #bubbles! Let me tell you what is all about.
We have used the first @eROSITA_SRG X-ray all-sky map to study the hot halo of the Milky Way, also called “circum-galactic medium” (CGM). This is a nice artist’s impression of how complicated the CGM of galaxy like our own can be (Image credit: Tumlinson et al. 2017)
The good sensitivity and image quality @eROSITA_SRG in soft X-rays allowed us to “see” weak disturbances and long-lived shock features imprinted on the hot CGM of the Milky Way. Can you spot the large bubbles in the eRASS1 map?
The northern arch-like feature (the North Polar Spur) was known since ROSAT times, more than 30 years ago. Here is a zoom on the southern bubble (greenish color) seen by @eROSITA_SRG
In fact, if we now look at the 0.6-1 keV X-ray image (most sensitive to gas at around 3 million degrees), subtracting all point sources, the full extent of these large bubbles becomes apparent. We think they are almost spherical thick shells of ~14 kpc diameter.
Ever heard about the Fermi Bubbles? These are similar, but smaller, features detected in gamma-rays. We suspect these two sets of bubbles are produced by the same energy injection event at the Galactic center. The image shows the Fermi bubbles in red and the eROSITA ones in cyan
The energy needed to inflate these balloons is equivalent to 100000 supernoavae, and was released about 20 million years ago. Was it the central supermassive black hole? We don’t know for sure. Certainly, these bubbles carry energy and mass, and shape the properties of the CGM
For more information, please have a look at our paper: https://www.nature.com/articles/s41586-020-2979-0