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Center for Astrophysics Research and Technologies Seminar Series Information


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Probing the Cause of Lagging Gaseous Halos with Radio Continuum Observations

Thursday April 26, 2018
2:00 pm

 Presenter:  Tim Braun (UNM)
 Series:  Center for Astrophysics Research and Technologies Seminar Series
 Abstract:  A gaseous halo is the interface between the disk of a galaxy and the surrounding intergalactic medium (IGM), making it an excellent laboratory to study galaxy evolution (e.g., accretion of IGM and disk feedback processes). Within the past twenty years, the kinematics of halo gas in galaxies has been observed to rotate slower than the gas in the disk of a galaxy with a decrease in rotation velocity with increasing vertical height off of the disk (lag). Simple ballistic interstellar medium models fail to predict the steepness of the observed lags. The addition of non-thermal pressure gradients from cosmic rays and magnetic fields to the ballistic model might explain the steepness of the observed lags.

In this work, we attempt to model the non-thermal pressure gradients in gaseous halos from a sub-sample of twelve edge-on galaxies in the Continuum Halos in Nearby Galaxies - an EVLA Survey (CHANG-ES) sample with measured lags. The initial CHANG-ES VLA observations (C-Band C,D array; L-Band B,C,D array) suffer from missing short-spacings, which limits the sensitivity to large-scale emission and total flux densities. This problem is corrected with follow-up GBT observations. We present results from our new C-band Stokes I GBT data reduction/imaging pipeline as well as results from our single dish and interferometric combination techniques to enhance the extended diffuse radio halos. Lastly, we outline our approach to 3D modeling of non-thermal pressures in NGC 891.
 Host:  Gregory Taylor
 Location:  Room 190, Physics & Astronomy

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