The Fermi bubbles are super-prominent, is eROSITA the first x-ray telescope sensitive to detect them?
Recently XMM looked at the centre of the galaxy, finding chimney-like structures which may link to the bubbles. This is on a much smaller region, however: http://www.esa.int/Science_Exploration/Space_Science/Giant_c...
Nothing since ROSAT has had the ability to map large areas like eROSITA/SRG. ABRIXAS was supposed to be the successor to ROSAT, but it failed shortly after launch.