UNVEILING THE MILKY WAY: A NEW TECHNIQUE FOR DETERMINING THE OPTICAL COLOR AND LUMINOSITY OF OUR GALAXY

We demonstrate a new statistical method of determining the global photometric properties of the Milky Way (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 data set from the Sloan Digital Sky Survey (SDSS), we exploit the inherent dependence of galaxies' luminosities and colors on their total stellar mass, M-star, and star formation rate (SFR), M-star, by selecting a sample of Milky Way analog galaxies designed to reproduce the best Galactic M-star and (M)over dot(star) measurements, including all measurement uncertainties. Making the Copernican assumption that the MW is not extraordinary among galaxies of similar stellar mass and SFR, we then analyze the photometric properties of this matched sample, constraining the characteristics of our Galaxy without suffering interference from interstellar dust. We explore a variety of potential systematic errors that could affect this method, and find that they are subdominant to random uncertainties. We present both SDSS ugriz absolute magnitudes and colors in both rest-frame z = 0 and z = 0.1 passbands for the MW, which are in agreement with previous estimates but can have up to similar to 3x lower errors. We find the MW to have absolute magnitude M-0(r) - 5 log h = -21.00(-0 .37)(+0.38) and integrated color (0)(g - r) = 0.682(-0.056)(+0.066), indicating that it may belong to the green-valley region in color-magnitude space and ranking it among the brightest and reddest of spiral galaxies. We also present new estimates of global stellar mass-to-light ratios for our Galaxy. This work will help relate our in-depth understanding of the Galaxy to studies of more distant objects.