The HI-rich elliptical galaxy NGC 5266: an old merger remnant?

Abstract

We present HI images for the dust-lane elliptical galaxy NGC 5266. This galaxy contains more than 10 billion solar masses of HI and our data show that the neutral hydrogen extends to about 8 arcmin each side of the nucleus, or 8 times the optical half-light radius. Surprisingly, the outer HI gas extends almost orthogonal to the optical dust lane. The overall HI kinematics can be successfully modeled by assuming that the gas lies in two orthogonal planes: in the plane of the dust lane in the central parts and perpendicular to this in the outer regions. The large amount of neutral gas observed and the HI morphology, suggest that this object may have formed from the merger of two gas rich spiral galaxies. If so, it probably represents a relatively old merger remnant since most of the HI appears settled. The mass-to-light ratio has also been derived with evidence for a dark matter halo around this galaxy.