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The high energy activity in the inner few degrees of the Galactic center istraced by diffuse radio, X-ray and gamma-ray emission. The physicalrelationship between different components of diffuse gas emitting at multiplewavelengths is a focus of this work. We first present radio continuumobservations using Green Bank Telescope and model the nonthermal spectrum interms of a broken power-law distribution of GeV electrons emitting synchrotronradiation. We show that the emission detected by Fermi is primarily due tononthermal bremsstrahlung produced by the population of synchrotron emittingelectrons in the GeV energy range interacting with neutral gas. Theextrapolation of the electron population measured from radio data to low andhigh energies can also explain the origin of FeI 6.4 keV line and diffuse TeVemission, as observed with Suzaku, XMM-Newton, Chandra and the H.E.S.S.observatories. The inferred physical quantities from modeling multi-wavelengthemission in the context of bremsstrahlung emission from the inner 300x120parsecs of the Galactic center are constrained to have the cosmic rayionization rate 1-10x10^{-15} s^-1, molecular gas heating rate elevating thegas temperature to 75-200K, fractional ionization of molecular gas 10^{-6} to10^{-5}, large scale magnetic field 10-20 micro Gauss, the density of diffuseand dense molecular gas 100 and 10^3 cm^{-3} over 300pc and 50pc pathlengths,and the variability of FeI Kalpha 6.4 keV line emission on yearly time scales.Important implications of our study are that GeV electrons emitting in radiocan explain the GeV gamma-rays detected by Fermi and that the cosmic rayirradiation model, like the model of the X-ray irradiation triggered by pastactivity of Sgr A*, can also explain the origin of the variable 6.4 keVemission from Galactic center molecular clouds.

astrophysical journal/the astrophysical journal

Interacting Cosmic Rays with Molecular Clouds: A Bremsstrahlung Origin  of Diffuse High Energy Emission from the Inner 2deg by 1deg of the Galactic  Center