1508.04446
Unveiling the Milky Way: a new technique for determining the optical color and luminosity of our Galaxy
Licquia, Newman, Brinchmann
Demonstrate a new statistical method of determining the global photometric properties of the MW to an unprecedented degree of accuracy, allowing our Galaxy to be compared directly to objects measured in extragalactic surveys. Capitalizing on the high-quality imaging and spectroscopy dataset from the SDSS, exploit the inherent dependence of galaxies' luminosities and colors on their total stellar mass, M*, and SFR, dot(M*), by selecting a sample of MW analog galaxies designed to reproduce the best Galactic M* and dot(M*) measurements, including all measurement uncertainties. Making the Copernican assumption that the MW is not extraordinary amongst galaxies of similar stellar mass and SFR, analyze the photometric properties of this matched sample, constraining the characteristics of our Galaxy without suffering interference from interstellar dust. Explore a variety of potential systematic errors that could affect this method, and found that they are subdominant to random uncertainties. Present both SDSS ugriz absolute magnitudes and colors in both rest-frame z=0 and z0.1 passbands for the MW, which are in agreement with previous estimates but can have up to ~3x lower errors. Find the MW to have absolute magnitude ^0M_r-5 log h = -21.00±0.38 and integrated color ^0(g-r)=0.682±0.06, indicating that it may belong to the green-valley region in color-magnitude space and ranking it amongst the brightest and reddest of spiral galaxies. Also present new estimates of global stellar M/L ratios for our Galaxy. This work will help relate the in-depth understanding of the Galaxy to studies of more distant objects.
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