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Impact of Nuclear Activity on the Galactic Halo

Published onJun 01, 2020
Impact of Nuclear Activity on the Galactic Halo

In this talk I will discuss observational evidence of the impact of nuclear activity on the Galactic Halo. Analyzing the UV absorption from HST/COS observations of 31 sightlines through the Magellanic Stream and Leading Arm, we find evidence of kinematic differences between the low and high ions in the Leading Arm, but no evidence of such differences in the Stream. This points to a single-phase model in the Stream and a multi-phase model for the Leading Arm. One explanation for this is a Seyfert flare in the Galactic Center several Myr ago, which would photo-ionize the Stream, but not the Leading Arm since it is shielded from the ionization cone. This model is supported by other evidence from Hα and UV line ratios measurements of the Stream. I discuss how, based on matching timescales, the Seyfert flare may have been the event that created the Fermi Bubbles.

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