[Seminars] FW: EFI Colloquium

[Ramona Echols]

REMINDER 

Starting in 10 minutes


    ** EFI COLLOQUIUM**
    
    TODAY Monday April 22, 2019
    PRC 201 3:30 PM
    
    Speaker: 
    TAKESHI OKA, UCHICAGO
    
    Title: 
    MEASUREMENT OF COSMIC RAYS IN THE GALAXY USING THE H3+ SPECTRUM
    
    Abstract:
    The Enrico Fermi Institute has published an enormous amount of direct
    measurements of cosmic rays but the measurements have been limited
    on the earth or in the solar vicinity. I would like to talk on our
    measurements of cosmic rays using chemistry and spectroscopy which
    I have used since the discovery of interstellar H3+ 
    in 1996 [1]. This method has no luxury of measuring the cosmic ray spectrum nor atomic identity
    but allows us to measure average cosmic ray energy far in the Galaxy
    like in the Galactic center (GC) and beyond. By using the H3+ 
    spectrum we have measured the cosmic ray ionization rate  to be on the order
    of 10-17 s-1 in dense clouds, 10-16 s-1 in di?use clouds in the Galactic disk,
    and 10-14 s-1 in the warm and di?use gas in the GC [2]. These results
    squarely negate the previous idea of the homogeneous filling of the
    Galaxy by cosmic rays. The cosmic ray energy density 1000 times higher
    in the GC than in the solar vicinity was unexpected and its astrophysical
    implication will be discussed.
    
    Warmly, 
     
    Ramona Echols,  EFI/HEP Secretary IV
    Enrico Fermi Institute 
    University of Chicago
    933 E 56th Street, PRC 101
    Chicago, IL 60637
    Phone: 773-702-8113
    Rechols06 at uchicago.edu
     
     
    
    

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