DGCE SIG Seminar

Galactic Center as an Extragalactic Tool: Gas and the Radiation Field from the Milky Way

Dhanesh Krishnarao, Colorado College

The inner Milky Way is home to many energetic phenomena impacting the interstellar medium and influencing the environment surrounding our Galaxy, including the Magellanic Clouds. One of the most important phenomena is gas flowing into the nucleus at high velocities along the bar that may later be expelled from Galactic Center in the massive biconical outflows of the Fermi Bubbles. The dense population of stars of various ages throughout the bar and Central Molecular Zone provide a unique source of ionizing radiation, resulting in an abundance of ionized gas. Recently, we found that the Fermi Bubbles can be seen in optical emission and spectroscopically mapped. Additionally, gas in the "Tilted Disk," a structure along the bar that is tilted off the Galactic midplane, is largely ionized and similar to a class of extragalactic systems known as Low Ionization (Nuclear) Emission Regions—LI(N)ERs. Our galaxy provides the only place in the universe where we can investigate the radiation source of these LI(N)ER systems and is crucial in order to understand both local and global conditions of the Milky Way, including the circumgalactic medium. Upcoming work to fully diagnose the radiation field escaping from the Galactic Center based on these results will provide rich constraints to several studies of gas surrounding and within the Milky Way and other galaxies.

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