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E. M. Schlegel (Harvard-Smithsonian CfA), S. S. Holt (Olin College of Engineering), R. Petre (NASA/GSFC)
We describe the 57.8 ksec Chandra observation of the diffuse emission in the nearby face-on spiral NGC 6946. After the removal of point sources, about 5900 net counts remain. The spectrum may be fit either with variable Mekal model or a thermal bremsstrahlung plus gaussians. The continuum temperatures for both models are identical within the uncertainties at 0.25 keV. For the variable Mekal model, only the abundances of Si and Fe differ significantly from solar with the abundance of Si elevated to about 3 while the Fe abundance is about 0.7. For the bremsstrahlung model, seven zero-width gaussians must be included to provide a good fit to the spectrum. The diffuse emission follows the spiral arms; an overlay of X-ray contours on a 6 cm polarized intensity map of Beck & Hoernes (1996) confirms the interarm appearance of the polarized emission. An extrapolation of the point source luminosity distribution shows the diffuse emission can not be the sum of unresolved point sources.
This research was supported by NASA contract number NAS8-39073 to the Smithsonian Astrophysical Observatory.
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Bulletin of the American Astronomical Society, 34, #4
© 2002. The American Astronomical Soceity.