Star Formation Histories of z <0.25 Galaxies from GALEX Samir Salim (UCLA) and the GALEX Science Team. RESULTS AND ANALYSIS Mass determination Kauffmann et al. determined masses using SDSS spectra (Hdelta & D4000) Comparison with our determination: Relative scatter 0.11 dex
Samir Salim (UCLA) and the GALEX Science Team
We derive physical parameters: stellar mass, SFR, dust attenuation and burst mass fractions, for 6500 galaxies observed in the UV by the Galaxy Evolution Explorer (GALEX) and present in the SDSS DR1 spectroscopic sample. Parameters are estimated by comparing each observed broad-band SED (2 GALEX + 5 SDSS bands) with a library of model galaxy SEDs. We are sensitive to SFRs as low as 10-3 M⊙/yr. The least massive galaxies have ratios of current to past-averaged SF rates (b-parameter) consistent with constant SF over a Hubble time. b correlates tightly with NUV−r color, implying that the SF history of a galaxy can be constrained on the basis of the UV/optical color alone. Also, the fraction of galaxies that have undergone a starburst episode within the last 1 Gyr steeply declines with mass.