Modelling simple stellar populations in the near-ultraviolet to near-infrared with the X-shooter Spectral Library (XSL)

We present simple stellar population models based on the empirical X-shooter Spectral Library (XSL) from near-ultraviolet (NUV) to near-infrared (NIR) wavelengths. The unmatched characteristics of relatively high resolution and extended wavelength coverage (350–2480 nm, R ∼ 10 000) XSL bring us closer bridging optical NIR studies intermediate-age old populations. It is now common find good agreement between observed predicted NUV properties clusters due our understanding main-sequence early giant phases stars. However, spectra populations are sensitive cool K M giants. asymptotic branch, especially thermally pulsing shapes 0.5–2 Gyr populations; tip red branch defines older therefore construct sequences average static giants, variable O-rich C-rich giants be included in separately. span metallicity range −2.2 < [Fe/H] +0.2 ages above 50 Myr, a broader than other spectral libraries. focus behaviour colours absorption-line indices as function age metallicity. Our can reproduce integrated Coma cluster galaxies at same level semi-empirical found literature. In NIR, there notable differences galaxies. Furthermore, expand values compared make it possible perform in-depth features consistently throughout clarify role evolved stars