Multi-wavelength features of Fermi Bubbles as signatures of a Galactic wind

TL;DR

This study uses hydrodynamical simulations to demonstrate that a star formation episode in the Milky Way's center can produce Fermi Bubbles with multi-wavelength features, aligning with observations across X-ray, gamma-ray, and microwave data.

Contribution

First hydrodynamical simulation showing star formation-driven Galactic wind can produce Fermi Bubbles matching multi-wavelength observations.

Findings

Star formation rate of ~0.5 M_sun/yr can generate bubbles resembling Fermi Bubbles.

Interaction with circum-galactic medium explains X-ray surface brightness and morphology.

In situ cosmic ray acceleration accounts for gamma-ray and microwave features.

Abstract

Using hydrodynamical simulations, we show for the first time that an episode of star formation in the center of the Milky Way, with a star-formation-rate (SFR) $\sim 0.5$ M$_\odot$ yr$^{-1}$ for $\sim 30$ Myr, can produce bubbles that resemble the Fermi Bubbles (FBs), when viewed from the solar position. The morphology, extent and multi-wavelength observations of FBs, especially X-rays, constrain various physical parameters such as SFR, age, and the circum-galactic medium (CGM) density. We show that the interaction of the CGM with the Galactic wind driven by a star formation in the central region can explain the observed surface brightness and morphological features of X-rays associated with the Fermi Bubbles. Furthermore, assuming that cosmic ray electrons are accelerated {\it in situ} by shocks and/or turbulence, the brightness and morphology of gamma-ray emission and the microwave haze can be explained. The kinematics of the cold and warm clumps in our model also matches with recent observations of absorption lines through the bubbles.