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The Hot Galactic Corona and the Soft X-ray Background

Published online by Cambridge University Press:  12 April 2016

Q. Daniel Wang
Q. Daniel Wang*
Affiliation:
Dearborn Observatory, Northwestern University 2131 Sheridan Road, Evanston, IL 60208-2900, USA

Abstract

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I characterize the global distribution of the ¾ keV band background with a simple model of the hot Galactic corona, plus an isotropic extragalactic background. The corona is assumed to be approximately polytropic (index = 5/3) and hydrostatic in the gravitational potential of the Galaxy. The model accounts for X-ray absorption, and is constrained iteratively with the ROSAT all-sky X-ray survey data. Regions where the data deviate significantly from the model represent predominantly the Galactic disk and individual nearby hot superbubbles. The global distribution of the background, outside these regions, is well characterized by the model; the 1σ relative dispersion of the data from the model is ~ 15%. The electron density and temperature of the corona near the Sun are ~ 1.1 × 10−3 cm−3 and ~ 1.7 × 106 K. The same model also explains well the 1.5 keV band background. The model prediction in the ¼ keV band, though largely uncertain, qualitatively shows large intensity and spectral variations of the corona contribution across the sky.

Type
Part VIII High-Velocity Clouds, Galactic Halo Models, Observations of the LMC
Information
International Astronomical Union Colloquium , Volume 166: The Local Bubble and Beyond , 1997 , pp. 503 - 512
Copyright
Copyright © Springer-Verlag 1998

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