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Astronomy Colloquium - "Velocity gradients: A radically new way of tracing interstellar magnetic fields"

Event Type
Seminar/Symposium
Sponsor
Department of Astronomy
Location
134 Astronomy
Date
Oct 24, 2017   3:45 pm  
Speaker
Alexandre Lazarian, University of Wisconsin, Madison
Contact
Rebecca Bare
E-Mail
rsbare@illinois.edu
Phone
217-333-3090
Views
38
Originating Calendar
Astronomy Colloquium Speaker Calendar
I shall introduce three new techniques of magnetic field tracing. The first two use Doppler-shifted emission lines and employs the gradients of velocity in order to trace magnetic fields in the diffuse interstellar media as well as to trace regions of star formation associated with the gravitational collapse. The differences between these techniques is that they use different observationally available measures, i.e. the first one uses the velocity centroids and the other uses velocity channel maps. 
I shall provide the theoretical justification of the use of these measures, its numerical testing as well as the comparison of the directions obtained with the velocity centroid gradients using GALFA HI data and those of magnetic field as traced by Planck as well as 13CO data and far infrared polarimetry. I shall also discuss the third technique which employs the synchrotron intensity gradients that also trace magnetic field and, unlike synchrotron polarization, are insensitive to Faraday rotation. I shall also show its correspondence with the magnetic field tracing by Planck and discuss the synergy of using this technique with synchrotron polarization studies. I shall discuss the big promise of the new techniques both for the star formation and CMB foreground studies. 
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