Erwin de Blok (University of Cape Town, South Africa)

THINGS: The HI Nearby Galaxy Survey - Erwin de Blok Colloquium

ATNF Marsfield Lecture Theatre

Abstract

In this talk I present first results from THINGS, the HI Nearby Galaxy Survey. THINGS used the VLA to obtain 21-cm HI observations of the highest quality (spatial resolution 6", velocity resolution < 5.2 km/s) of 34 nearby galaxies. The scientific goals of THINGS are to investigate key characteristics of the interstellar medium related to galaxy morphology, star formation and mass distribution (dark and visible) along the Hubble sequence. I summarize some of the first results from THINGS and briefly discuss topics such as the star formation law in disk galaxies, star formation thresholds, the edges of HI disks, and holes and shells. I then discuss the rotation curves and dark matter distribution in the THINGS galaxies in more detail. The main result here is that despite the increase in resolution, the rotation curves are still incompatible with Cold Dark Matter predictions. Furthermore, we have measured the non-circular motions within the HI disks in our sample, and find that these are not large enough to explain the discrepancy.