Annie Hughes (Max Planck Institute for Astronomy)

The PAWS View of Giant Molecular Clouds, Gas Flows and Star Formation in M51-- Annie Hughes Colloquium

Marsfield Lecture Theatre

Abstract

I will present an overview of the latest results from the PdBI Arcsecond
Whirlpool Survey (PAWS), which has mapped CO(1-0) emission in the nearby
grand-design spiral galaxy M51 at 40pc resolution and is sensitive to
giant molecular clouds (GMCs) with masses above 10^5 Msun. Across the PAWS
field, the CO emission is an order of magnitude brighter, and exhibits
linewidths that are several times larger than the CO emission detected by
recent high resolution surveys of the LMC and M33. Furthermore, most of
the CO emission in M51 resides in spatially extended kpc-sized structures,
rather than the discrete clouds that are typical in these nearby dwarf
galaxies. In the inner disk of M51, the properties of the CO emission show
significant variation that can be linked to the dynamical environment in
which the molecular gas is located. The observed gas motions suggest a
strong response to torquing by the stellar spiral pattern, and we find
that dynamically distinct regions exhibit different GMC properties and
mass spectra, as well as distinct patterns of star formation. I will
discuss these results in the context of the scatter in GMC scaling
relations and extragalactic star formation laws.