UV/Hα Turmoil



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Lee, Janice C. and Gil de Paz, Armando and Tremonti, Christy and Kennicutt, Robert (2011) UV/Hα Turmoil. In UP2010: Have observations revealed a variable upper end of the initial mass function. ASP Conference Series (440). Astronomical Society of the Pacific, San Francisco, pp. 179-187. ISBN 978-1-58381-760-5

[thumbnail of gildepaz581preprint.pdf]

Official URL: http://arxiv.org/abs/1011.2181


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_⨀ 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.

Item Type:Book Section
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© Astronomical Society of the Pacific.
Conference on UP2010 (2010. Sedona, EE.UU.). JCL gratefully acknowledges support from the Hubble and Carnegie Postdoctoral Fellowship Programs. She is also thankful for funding from the GALEX project, which enabled not only the science presented here, but also the organization of the overall Up2010 workshop.

Uncontrolled Keywords:Star-formation histories; Galaxy redshift survey; Irregular galaxies; Formation rates; Dwarf galaxies; Local volume; Hα; Starbursts; Evolution; Sample
Subjects:Sciences > Physics > Astrophysics
Sciences > Physics > Astronomy
ID Code:35490
Deposited On:05 Feb 2016 13:18
Last Modified:10 Dec 2018 15:05

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