Missing Baryons and Metals Around Galaxies: Hot Gaseous Halos and Dust

Wednesday, June 01, 2016 - 3:30pm to 4:30pm PDT
Joel Bregman
University of Michigan
N232, Room 103
Event Type: 

A census of the stars and warm/cool gas in the Local Universe reveals that they account for only half of the baryons in the universe and about 10% of the metals. It is suggested that the missing baryons lie in hot gaseous extended halos around galaxies (1-5E6 K) as well as in the unvirialized cosmic web. We detect these hot halos around the Milky Way and external galaxies and find that, within the virial radius, the gaseous halos have masses comparable to the stellar masses, but still fall short of accounting for the missing baryons. The metallicity is a combination of the gas phase component (0.3 solar) and the contribution from dust, which contributes a comparable amount of metals. We detect dust to 20 kpc from the disks of spiral galaxies by UV scattered halos. This is consistent with much more extended dust seen around galaxies, which together, show that there is more dust outside of galaxy disks than inside.

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