Fermi/eROSITA bubbles

Listen to my talk on the Fermi Bubbles. Delivered at Kavli Institute of Theoretical Physics (KITP), University of California, Santa Barbara

The decade-old discovery of two giant gamma-ray bubbles toward the Galactic Center (GC), called the Fermi Bubbles, spurred a discussion of their origin. The recent discovery of X-ray structures in the southern Galactic hemisphere by e-Rosita, which appear to be the counterparts of the known X-ray features in the northern hemisphere, has reignited the quest for the origin of the Fermi/eROSITA bubbles (FEBs).
Several models have tried to explain these bubbles as a result of supernovae-driven galactic outflow, while some others have proposed a supermassive black hole-driven outflow. This is one of my active areas of research.

Some throwback images

Simulated evolution of a supernovae-driven superbubble in our Galaxy. Image source Sarkar, K. C. etal. 2019. The image shows the density map of the circumgalactic medium in the simulated galaxy. Our vantage point (Solar point of view) is shown using the white circle. The possible density structure for the Fermi/eROSITA bubble is shown in the 3rd panel.

X-ray surface brightness of a supernovae driven outflow as seen from the Solar point of view. The blue solid line shows the outer edge of the gamma-ray emitting bubble (Fermi Bubble). Details are given in Sarkar, K. C. etal. 2019.

Relevant publications

The Fermi/eROSITA Bubbles: A look into the nuclear outflow from the Milky Way: Sarkar K. C., 2024
Misaligned Jets from Sgr A* and the Origin of Fermi/eROSITA Bubbles: Sarkar K. C., Mondal S., Sharma P., Piran T., 2023, ApJ, 951, 36.
Fermi bubbles: the collimated outburst needed to explain forward-shock edges: Mondal S., Keshet U., Sarkar K. C., Gurwich I., 2022, MNRAS, 514, 2581.
Possible connection between the asymmetry of the North Polar Spur and Loop I and Fermi bubbles: Sarkar K. C., 2019, MNRAS, 482, 4813.
Clues to the origin of Fermi bubbles from O viii/O vii line ratio: Sarkar K. C., Nath B.~B., Sharma P., 2017, MNRAS, 467, 3544.
Multiwavelength features of Fermi bubbles as signatures of a Galactic wind: Sarkar K. C., Nath B.~B., Sharma P., 2015, MNRAS, 453, 3827.

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