Joint Chandra/XMM-Newton Observation of NGC1407/1400 complex

The nearby dark group centered on NGC 1407 is notable for a nearby bright galaxy (NGC 1400) with a velocity differing by at least 1200 km/s. This large velocity difference, plus controversy over these two galaxies' respective distances, has led to a wide range of mass estimates for this group. Our analysis of XMM-Newton data reveals an extended region of enhanced surface brightness near NGC 1400 which may be a cold front. We also find that the hottest regions lie between NGC 1400 and 1407, suggesting that their atmospheres are colliding. We propose a 55 ks Chandra ACIS-S pointing of NGC 1400 to reveal the nature of the enhanced region, and a 30 ks XMM-Newton pointing covering the east side of NGC 1407 to obtain a complete temperature map as well as a total group mass profile.