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Modelling high resolution spectra of galaxies with variable chemical abundances ratios

Final Activity Report Summary - HIRVACH (Modelling high resolution spectra of galaxies with variable chemical abundances ratios)

The chemical pattern of galaxies is a keystone in order to understand their origin and evolution. The extraction of this information from galaxy spectra requires high quality galaxy models as well as the use of sophisticated techniques for the interpretation of integrated spectra of galaxies, such as full spectrum fitting. In recent years efforts were made in producing models with variable abundance patterns that would allow us to interpret the hundreds of thousands of spectra made available nowadays by astronomical surveys.

This Marie Curie Fellowship rendered possible to produce high resolution spectral models which allowed for the derivation of the iron and alpha-elements abundances in galaxies (Coelho et al. 2007, MNRAS 382, 498, Lee et al. 2009, ApJ 694, 902, Coelho et al. being in preparation by the end of the project), superseding previous works in two aspects:

1. we provided, for the first time, full spectral models through which a considerably larger number of observables could be studied such as spectra, spectral indices and broad-band colours
2. our ingredients were computed consistently, reaching a new level of accuracy.

Our models were calibrated so as to better match observed galaxy spectra (Walcher et al. 2009, MNRAS accepted). This work was anticipated to continue in the following years by expanding and updating the models (Coelho et al. in preparation) and applying them to observations in order to better understand the chemical enrichment history of the universe (Gallazzi et al. in preparation).

Therefore, we now better understand how the chemical pattern impacts the stellar spectra and evolution of the stars and we have more accurate tools to interpret galaxy spectra. This work opened new opportunities for precision measurements of abundance ratios in galaxies.