UV/Hα Turmoil

Type Conference Paper
Names J. C. Lee, A. G. de Paz, C. Tremonti, R. Kennicutt, Loval Volume Legacy Team, Marie Treyer, Ted K. Wyder, James D. Neill, Mark Seibert, Janice C. Lee
Proceedings Title ASP Conference Series
Conference Name UP2010: Have Observations Revealed a Variable Upper End of the Initial Mass Function? Proceedings of a Conference Held at Sedona, Arizona, USA 20-25 June 2010
Place San Francisco, CA
Publisher Astronomical Society of the Pacific
Volume 440
Pages 179
Series ASP Conference Series
Date June 1, 2011
URL http://adsabs.harvard.edu/abs/2011ASPC..440..179L
Library Catalog NASA ADS
Abstract A great deal of our understanding of star formation in the local universe has been built upon an extensive foundation of Hα observational studies. However, recent work in the ultraviolet (UV) with GALEX has shown that star formation rates (SFRs) inferred from Hα in galactic environments characterized by low stellar and gas densities tend to be less than those based on the UV luminosity. The origin of the discrepancy is actively debated because one possible explanation is that the stellar initial mass function is systematically deficient in high mass stars in such environments. In this contribution, we summarize our work on this topic using a dwarf galaxy dominated sample of ˜300 late-type galaxies in the 11 Mpc Local Volume. The sample allows us to examine the discrepancy between Hα and UV SFRs using a statistical number of galaxies with activities less than 0.1 M&sun; yr-1. A range of potential causes for such an effect are reviewed. We find that while the IMF hypothesis is not inconsistent with our observations, alternate explanations remain that must be investigated further before a final conclusion can be drawn.
UW-Madison Astronomy Home