A new superwind galaxy: XMM-Newton observations of NGC 6810

We present the first imaging X-ray observation of the highly inclined (i = 78 deg) Sab Seyfert 2 galaxy NGC 6810 using XMM-Newton, which reveals soft X-ray emission that extends out to a projected height of ~7 kpc away from the plane of the galaxy. The soft X-ray emission beyond the optical disk of the galaxy is most plausibly extra-planar, although it could instead come from large galactic radius. This extended X-ray emission is spatially associated with diffuse H-alpha emission, in particular with a prominent 5-kpc-long H-alpha filament on the north-west of the disk. A fraction <~35% of the total soft X-ray emission of the galaxy arises from projected heights |z| > 2 kpc. Within the optical disk of the galaxy the soft X-ray emission is associated with the star-forming regions visible in ground-based H-alpha and XMM-Newton Optical Monitor near-UV imaging. The temperature, super-Solar alpha-element-to-iron abundance ratio, soft X-ray/H-alpha correlation, and X-ray to far-IR flux ratio of NGC 6810 are all consistent with local starbursts with winds, although the large base radius of the outflow would make NGC 6810 one of the few ``disk-wide'' superwinds currently known. Hard X-ray emission from NGC 6810 is weak, and the total E=2-10 keV luminosity and spectral shape are consistent with the expected level of X-ray binary emission from the old and young stellar populations. The X-ray observations provide no evidence of any AGN activity. We find that the optical, IR and radio properties of NGC 6810 are all consistent with a starburst galaxy, and that the old classification of this galaxy as a Seyfert 2 galaxy is probably incorrect.