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Paper: Evidence for Initial Mass Function Variations from the Integrated Light of Sloan Digital Sky Survey Galaxies
Volume: 440, UP2010: Have Observations Revealed a Variable Upper End of the Initial Mass Function?
Page: 251
Authors: Hoversten, E. A.; Glazebrook, K.
Abstract: The Hα equivalent width (EW) is the ratio of the Hα flux to the continuum at 6565Å. In normal star forming galaxies the Hα flux is dominated by reprocessed photons from stars with masses greater than 10 M and the 6565Å continuum is predominantly due to 0.7–3.0 M red giant stars. In these galaxies the Hα EW is effectively the ratio of high mass to low mass stars and is thus sensitive to the stellar initial mass function (IMF). In Hoversten & Glazebrook (2008) we used ∼131,000 galaxies from the Sloan Digital Sky Survey to show evidence for systematic variations in the IMF with galaxy luminosity. In this proceeding we use that sample, with the addition of HδA measurements, to investigate other parameterizations of the IMF. We find evidence for IMF variations with surface brightness, and also show that, modulo uncertainties in spectral synthesis models, that 120 M stars are important in accounting for the observed Hα EW distribution.
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