[Seminars] EFI Colloquium

[Ramona Echols]

** 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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