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The grand-design face-on spiral galaxy NGC6946 is remarkable because of itshigh star formation activity, the massive northern spiral arm, and the magneticarms, which are observed in polarized radio synchrotron emission and arelocated between the optical arms and possibly are magnetic reconnectionregions. X-ray observations of NGC6946 performed with XMM-Newton were used tostudy the emission from X-ray point sources and diffuse hot gas, including themagnetic arms and the halo. Spectral fitting of the diffuse X-ray emissionallowed us to derive temperatures of the hot gas. With assumptions about theemission volume, this allowed us to estimate gas densities, masses, and coolingtimes. To explain the X-ray emission from the spiral arms of NGC6946two-temperature plasma models are needed to account for the disk and haloemission. The interarm regions show only one thermal component. We observe thatthe temperature of the hot gas in and above the magnetic arm regions increasesslightly when compared to the average temperatures in the areas in and abovethe spiral arms. For the southwestern part of the disk, which is depolarized inthe radio range by Faraday rotation, we find more efficient mixing of disk andhalo gas. We propose magnetic reconnection in the magnetic arm regions ofNGC6946 as the possible cause of the additional heating of the gas and orderingof the magnetic fields. In the southwestern part of the galactic disk weobserved indications of a possible faster outflow of the hot gas. A very hotgas within the MF16 nebula possibly suggests shock heating by a supernovaexplosion.

Hot gas and magnetic arms of NGC 6946: indications for reconnection heating?