Speaker
Miwa Goto
(USM/LMU)
Description
Cosmic ray is a unique place that high-energy astrophysics meets low-energy chemistry. The ion molecule H3+ is the best chemical probe of the cosmic ray ionization rate, because of the simplicity of the chemical process. Meanwhile, a new gamma-ray observation identified a point like source near Sgr A*. To produce the gamma-ray flux discovered by HESS collaboration by a neutral pion decay, one needs cosmic-ray proton flux as high as 7e4 protons/cm2/s/str/(nucleon/GeV), which is 10^5 times higher than the solar neighborhood. Such a high proton flux calls for the hydrogen ionization rate 10^5 times larger than the Galactic disk, while there is no hint of such enhanced cosmic ray flux found in view of H3+ chemistry. The huge discrepancy underscores our limited understanding of high energy environment in the central parsec of the Galaxy.
Author
Miwa Goto
(USM/LMU)