MEASURING GALAXY STAR FORMATION RATES FROM INTEGRATED PHOTOMETRY: INSIGHTS FROM COLOR-MAGNITUDE DIAGRAMS OF RESOLVED STARS

We use empirical star formation histories (SFHs), measured from Hubble-Space-Telescope-based resolved star color-magnitude diagrams, as input into population synthesis codes to model the broadband spectral energy distributions (SEDs) of 50 nearby dwarf galaxies (6.5 < log M sub(*)/M sub([middot i...

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Bibliographic Details
Published in:	The Astrophysical journal 2013-07, Vol.772 (1), p.1-19
Main Authors:	Johnson, Benjamin D, Weisz, Daniel R, Dalcanton, Julianne J, Johnson, L C, Dale, Daniel A, Dolphin, Andrew E, de Paz, Armando Gil, KENNICUTT, ROBERT C, Lee, Janice C, Skillman, Evan D, Boquien, Mederic, Williams, Benjamin F
Format:	Article
Language:	eng
Subjects:	Astrophysics ASTROPHYSICS, COSMOLOGY AND ASTRONOMY Bands Broadband COLOR DIAGRAMS DWARF STARS EMISSION ENERGY SPECTRA FLUCTUATIONS FORECASTING GALAXIES LUMINOSITY Mathematical models PHOTOMETRY RELIABILITY Sciences of the Universe SPACE SPACE VEHICLES Star formation STARS SYNTHESIS TELESCOPES ULTRAVIOLET RADIATION
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Summary:	We use empirical star formation histories (SFHs), measured from Hubble-Space-Telescope-based resolved star color-magnitude diagrams, as input into population synthesis codes to model the broadband spectral energy distributions (SEDs) of 50 nearby dwarf galaxies (6.5 < log M sub(*)/M sub([middot in circle]) < 8.5, with metallicities ~10% solar). In the FUV through i bands, we find that the observed and modeled SEDs are in excellent agreement. In the Spitzer 3.6 mu m and 4.5 mu m bands, we find that modeled SEDs systematically overpredict observed luminosities by up to ~0.2 dex, depending on treatment of the TP-AGB stars in the synthesis models. We assess the reliability of UV luminosity as a SFR indicator, in light of independently constrained SFHs. We do find a relationship between UV emission timescale and broadband UV-optical color, though it is different than predictions based on exponentially declining SFH models. Our findings have significant implications for the comparison of UV-based SFRs across low-metallicity populations with diverse SFHs.
ISSN:	0004-637X 1538-4357