The eROSITA bubbles rewrote the Galactic Center's energy history: enormous X-ray-emitting shells extending roughly 14 kiloparsecs above and below the plane, enclosing the previously known Fermi gamma-ray bubbles and testifying to an energy injection of order 10^56 erg in the Milky Way's past (Predehl et al. 2020). They are among the largest coherent structures in the Galaxy.
Their shape is the problem. A central engine, whether an outburst of Sgr A* or a nuclear starburst, should inflate bipolar, axisymmetric bubbles, and the observed structures refuse the symmetry: the morphology is lopsided, with brightness enhancements and extensions favoring particular directions, the northern structure tilting and the eastern features more prominent than simple central-injection geometry produces (Ponti et al. 2021). Restoring the asymmetry within standard models requires auxiliary machinery, a tilted or precessing jet history, an asymmetric ambient halo medium that deflected the outflow, or multiple injection episodes with different geometries, each tuned to the morphology after the fact rather than predicted by the engine physics.
The standing is an active morphology debate with the engine question, AGN outburst versus starburst, still open, and the asymmetry question, why these directions, unanswered by any model in which the Galaxy's surroundings are statistically featureless.