Piercing the Galactic Bubbles: Thermal Structure using Suzaku Data

Feedback from star-formation and/or super-massive black hole near the center of a galaxy are essential ingredients in the models of galaxy formation and evolution. For our Milky-Way, the recently discovered eROSITA bubbles and the well-known Fermi bubbles provide a great channel to understand the effects of feedback on the Galactic evolution. These magnificent bubbles attest to the Galactic center (GC) feedback, injecting energy/momentum into the Milky-Way halo. In order to understand the feedback process, it is important to constrain the thermal structure and thereby measure the energetics of the bubbles. Though the new eROSITA maps clearly show the enhance X-ray emission from the Galactic bubbles, the thermal properties of these bubbles remain largely unknown.

I will present the results of our recent Suzaku survey of the Galactic bubbles characterizing their thermal structure. We found with high confidence that the X-ray emission of the bubbles is best described by two thermal components, one near Galaxy’s virial temperature kT ~ 0.2 keV and the other at super-virial temperatures ranging between kT = 0.4–1.1 keV, contrary to the previous assumptions of a single temperature. I will provide the revised estimates of the energetics and the age of the bubbles.