Question

The Fermi Bubbles are two massive structures of high-energy gamma-ray and X-ray emission extending approximately $25{}000\text{ light-years}$ above and below the center of the Milky Way galaxy. Astronomers have proposed three models to explain the origin of these bubbles.

*Model 1*
The bubbles were inflated by a pair of highly collimated plasma jets ejected perpendicular to the galactic plane. These jets were powered by a single, rapid accretion event onto Sagittarius $\text{A}^*$ ($\text{Sgr A}^*$), the supermassive black hole at the galactic center. This event occurred $3\text{ to }6\text{ million years}$ ago and lasted for less than $100{}000\text{ years}$. The bubbles are relatively young structures formed by this brief, explosive release of magnetic and kinetic energy.

*Model 2*
The bubbles are the result of a sustained galactic wind driven by a period of intense starburst activity near the galactic center. Over the past $10\text{ million years}$, thousands of massive stars underwent core-collapse supernovae, releasing kinetic energy and stellar winds. This cumulative energy pushed gas out of the galactic disk, slowly inflating the bubbles over millions of years. Consequently, the gas within the bubbles should contain high concentrations of heavy elements synthesized during these supernovae.

*Model 3*
The bubbles were formed by a series of periodic, discrete energy injections over the last $5\text{ million years}$. These injections occurred when individual stars passed too close to $\text{Sgr A}^*$ and were torn apart by tidal forces, a process known as a Tidal Disruption Event (TDE). The accretion of this stellar debris onto $\text{Sgr A}^*$ generated recurring, episodic outflows. Rather than a single massive event or steady stellar winds, the current volume of the bubbles is the cumulative result of these individual stellar destruction episodes.

Based on the passage, match each of the three models with the statement that best represents its underlying hypothesis or key belief.