Peculiar properties of 2 unusually X-ray bright early type galaxies

Abstract

Two X-ray bright early type galaxies, selected for their unusually high X-ray to optical flux ratio, have been observed at high spatial resolution with the ROSAT HRI. Both sources are clearly extended (more than 250 kpc in radius), thus excluding a nuclear origin of the high X-ray emission. A small group of galaxies observed around IC 1262 could be the most natural explanation for the high X-ray luminosity observed. NGC6159 could be similarly explained, although there are to date no spectroscopic confirmations of a group of galaxies associated with it. The X-ray properties of these two sources are discussed in the context of the properties of groups of galaxies. A peculiar very bright feature, in the shape of an arc, is detected at the center of the IC 1262 image. This could be the signature of a recent merger, or of peculiar high velocities in the group.

Accepted for publication, A&A, Main Journal