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UniMass - Gustav Stromback

I am a PhD student within the Excellence Grant Team project 'UNIMASS", PI Claudia Maraston.
The aim of this project is to understand the formation and evolution of galaxies through their stellar populations. The analysis is performed by means of stellar population models - a fundamental tool for determining crucial physical parameters of galaxies, such as ages and masses. The Maraston (2005) models were a large improvement over its predecessors, in particular due to a proper treatment of the thermally pulsing asymptotic giant branch (TP-AGB) stellar evolutionary phase, which helped to overcome many of the problems in determining ages and masses of galaxies, especially at high redshift.
With the advent of large galaxy surveys - such as the Sloan Digital Sky Survey (SDSS) and GAMA, producing enormous amounts of high-resolution spectra - came also the need for stellar population models of comparable resolution over a reasonable wavelength range. The cornerstone of my PhD studies within the UNIMASS Excellence Grant team project, is to produce such models, mainly by implementing several different recently published catalogues of observed medium-to-high resolution, flux-calibrated stellar spectra (Pickles98, STELIB, MILES and ELODIE) into the Maraston (2005) code. These empirically-based stellar population models may avoid any possible shortcomings regarding the spectral shape of the theoretical stellar spectra (as shown in Maraston et al. 2009), and have the advantage of being based on observations made with the same instruments that have been used in several galaxy surveys, thus reducing systematic errors. They are, however, restricted in wavelength coverage, and limited to the distinct chemical pattern of the Milky Way, which is why we use a combination of the empirical libraries and new, high-resolution theoretical libraries (UVBLUE, MARCS) to produce our stellar population models.
The new models, together with the improved flexibility of the M05 code to adapt to new data sets, will in the future lead to a much more reliable determination of galaxy and star cluster physical parameters. Our models are already in use in SDSS-III/BOSS, in GAMA, in COSMOS. We shall made them available on our webpage soon.