0 Assigned ID: 1073 ----- Attempting Submission 1 (Fri Apr 10 23:46:50 GMT 2015) ----- Translating observed flux from galaxies into meaningful astrophysical quantities relies on "stellar population synthesis" (SPS) models. These models are broadly applied throughout extragalactic astronomy, at both high and low redshifts and to both photometric and spectroscopic spectral energy distributions (SEDs). Despite their widespread use, SPS models suffer from systematic biases that stem from incomplete input physics and are unreliable when used to derive physical parameters, due to inherent degeneracies in intepreting the SED. Unfortunately, it is difficult to predict how these limitations propagate into uncertainties in galaxy properties, or how the models perform when used on sub-kiloparsec scales. Uncertainties in SPS models are becoming the limiting factor in our interpretation of galaxy spectra, but remarkably, there is no existing ground truth data against which to test these models, aside from stellar clusters. This proposal is the first step in remedying this situation. We propose to use resolved stellar population observations from HST to constrain the stellar masses, ages, and star formation histories in regions matched to 2D spectroscopic observations from MaNGA. By sampling many subregions of a single galaxy, we will generate a publicly-released library of galaxy spectra matched to the true underlying stellar populations. This library will provide an initial "gold standard" comparison set that can be used to assess the accuracy of any SPS model. UNRESOLVED STELLAR POPULATIONS AND GALAXY STRUCTURE 0 Regular false false false false false SUPPORTED