HIRVACH · Modelling high resolution spectra of galaxies with variable chemical abundances ratios
FP6 — Marie Curie Actions (Human Resources and Mobility)
- Duration
- 2007-07-01 → 2009-06-30
- EU contribution
- €144,000
- Participants
- 1
- Scheme
- IIF
Lines connect the coordinator with its partners.
Results in brief
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.
Data: CORDIS, © European Union
Project objective
One of the most exciting recent developments in astrophysics has been the observation by large international consortia of hundreds of thousands of high-resolution spectra of galaxies in the local and distant Universe. The interpretation of these spectra in terms of stellar ages and metallicities is the key to reconstructing the star formation and chemical enrichment histories of the Universe.So far, however, such interpretations have been hampered by the fact that current models rely on spectral libraries of observed stars in the Milky Way and Magellanic Clouds, which have solar metal-abundance ratios at high metallicities. In contrast, the spectra of external galaxies appear to often be dominated by stars with non-solar metal abundance ratios (e.g., super solar alpha/Fe for massive galaxies). Until now, therefore, no spectral evolution model could help us fully exploit the wealth of information on chemical enrichment that is encoded in galaxy spectra. Only a few attempts were made to take into account the dependence of some spectral features on metal-abundance ratios.During my PhD thesis, I computed a comprehensive grid of high-resolution stellar spectra for non-solar mixtures of light elements at different metallicities. In collaboration with stellar evolution experts, we have assembled a grid of stellar evolutionary tracks for the same set of element mixtures. I plan to combine my spectral library with these evolutionary tracks to obtain the first fully consistent population synthesis models allowing the spectral interpretation of star clusters and galaxies in a wide range of chemical compositions.I will exploit this extremely powerful tool to quantify the effects of changes in abundance ratios on standard diagnostics of age and metallicity in galaxy spectra. By appealing to efficient techniques to interpret the large number of spectra gathered by modern galaxy surveys, I will be able to derive unprecedented constraints on the chemical evolution of galaxies.
Original text from CORDIS.
Participants
- CENTRE NATIONAL DE LA RECHERCHE SCIENTIFIQUE · PARISCoordinatorFrance
Links
Data: CORDIS, © European Union