ABSTRACT The Milky Way is surrounded by a hot diffuse circumgalactic medium (CGM) with temperatures of millions of degrees. Recent X-ray observations with the eROSITA satellite discovered a significant temperature asymmetry of this hot CGM, with the southern hemisphere being on average hotter than the northern one by a relative difference of T/T 12~{\ per\ cent}, where T is averaged over the entire CGM. In this letter, we investigate whether the passage of the Magellanic Clouds can be responsible for this asymmetry by means of a hydrodynamical/N-body simulation. In the simulation, the Magellanic Clouds induce a relative motion of the Milky Way’s disc of up to 40\, km s^-1. This motion leads to compression of the CGM gas in the southern hemisphere, resulting in an overall temperature increase in that region. We estimate a south-north temperature difference of T/T 13~{\ per\ cent}–20 per cent, consistent with the observations. We find that this temperature asymmetry is a recent phenomenon that began 100\, Myr ago.
Oprea et al. (Tue,) studied this question.