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Session 32 - General ISM.
Oral session, Wednesday, January 07

[32.06] RXTE Measurement of the Diffuse X-ray Emission from the Galactic Ridge: Implications for the Energetics of the Interstellar Medium

A. Valinia (NASA/GSFC and NAS/NRC), F. E. Marshall (NASA/GSFC)

The diffuse X-ray emission from the thin disk surrounding the Galactic mid-plane (or the so called Galactic ridge) was measured with RXTE PCA (1^\circ FWHM circular field of view, 2-60 keV energy band) in order to determine the spatial extent, spectral nature, and origin of the emission. The survey reveals that the diffuse emission is comprised of at least 2 spatial components: i) a thin disk of width 0.1^\circ-0.7^\circ centered on the galactic mid-plane, and ii) a broadly distributed component that can be approximated as a Gaussian function with FWHM \approx 8^\circ. Spectral measurements in the 3-35 keV band reveal that the diffuse emission has both thermal and non-thermal origins. The thermal component can be well modelled by an absorbed Raymond-Smith plasma component of temperature 1-2 keV, while the power law is well represented with a photon index of \approx 2.5. The thermal component of the emission can be modelled by a collection of supernova remnants (SNR) in the galaxy. The non-thermal component is most likely due to non-thermal emission from the edge of SNR remnants, electron bremsstrahlung, and inverse Compton scattering. We will discuss possible contributions from each radiation mechanism.

Program listing for Wednesday