News and Events

Colloquium

Speaker

Gerhardt Meurer

When

April 22, 2008

Where

Workman 101

Time

4pm

Topic

Star Formation in HI Selected Galaxies - Scaling Relations and The Initial Mass Function

Abstract

I will show data from the Survey of Ionization in Neutral Gas Galaxies (SINGG) and the Survey of Ultraviolet emission in Neutral Gas Galaxies (SUNGG) which survey the star formation properties of HI selected galaxies as traced by H-alpha and Ultraviolet emission, respectively. The correlations found demonstrate a strong relationship between the ISM, young ionizing stars and the old stellar populations. For example the correlation between star formation intensity and the HI cycling time is tighter than the Kennicutt-Schmidt Star Formation Law. The existence of an HI - star formation connection is somewhat of a mystery since stars form in the molecular not the neutral ISM, while the highest mass stars and the HI have very different distributions in galaxies. The ratio of integrated H-alpha and UV fluxes varies systematically with other galaxy properties. This result is robust against assumptions about dust extinction and star formation history assumptions. We favor the interpretation that this is due to a non-uniform IMF at the high-mass end. This result has enormous implications for galaxy evolution in both the near and distant universe.

See the full colloquium schedule for other seminars this semester.