Synthetic stellar and SSP libraries as templates for Gaia simulations

ESA's Gaia mission will collect low resolution spectroscopy in the optical range for ∼10 9 objects. Com- plete and up-to-date libraries of synthetic stellar spectra are needed to built algorithms aimed to automatically derive the classification and the parametrization of this huge amount of data. In addition, libraries of stellar spectra are one of the main ingredients of stellar population synthesis mod- els, aiming to derive the properties of unresolved stellar populations from their integrated light. We present (a) the newly computed libraries of synthetic spectra built by the Gaia community, covering the whole optical range (300- 1100 nm) at medium-high resolution of (0.3 nm) for stars spanning the most different types, from M to O, from A- peculiar to Emission lines to White Dwarfs, and (b) the im- plementation of those libraries in our SSP code (Tantalo in The Initial Mass Function 50 Years Later, 327:235 2005), exploring different stellar evolution models.