Suchergebnisse

The typical methodology for comparing simulated galaxies with observational surveys is usually to apply a spatial selection to the simulation to mimic the region of interest covered by a comparable observational survey sample. In this work, we compare this approach with a more sophisticated post-processing in which the observational uncertainties and selection effects (photometric, surface gravity and effective temperature) are taken into account. We compare a 'solar neighbourhood analogue' region in a model MilkyWay-like galaxy simulated with RAMSES-CH with fourth release Gaia-ESO survey data. We find that a simple spatial cut alone is insufficient and that the observational uncertainties must be accounted for in the comparison. This is particularly true when the scale of uncertainty is large compared to the dynamic range of the data, e.g. in our comparison, the [Mg/Fe] distribution is affected much more than the more accurately determined [Fe/H] distribution. Despite clear differences in the underlying distributions of elemental abundances between simulation and observation, incorporating scatter to our simulation results to mimic observational uncertainty produces reasonable agreement. The quite complete nature of the Gaia-ESO survey means that the selection function has minimal impact on the distribution of observed age and metal abundances but this would become increasingly more important for surveys with narrower selection functions.© 2017 The Author(s). ; This is based on data products from observations made with ESO Telescopes at the La Silla Paranal Observatory under programme ID 188.B-3002 (the Gaia-ESO Public Spectroscopic Survey). We acknowledge the insightful comments and support provided by our colleagues Stefano Pasetto, Daisuke Kawata, Rob Thacker and Dimitris Stamatellos. We would thank the anonymous referee for a very constructive report of the work presented here. BBT acknowledges the support of STFC through its PhD Studentship Programme (ST/F007701/1). We also acknowledge the generous allocation of resources from the Partnership for Advanced Computing in Europe (PRACE) via the DEISA Extreme Computing Initiative (PRACE-3IP Project RI-312763 and PRACE-4IP Project 653838) and STFC's DiRAC Facility (COSMOS: Galactic Archaeology). CGF acknowledges funding from the European Research Council for the FP7 ERC starting grant project LOCALSTAR and the DiRAC Complexity system, operated by the University of Leicester IT Services, which forms part of the STFC DiRAC HPC Facility (www.dirac.ac.uk). This equipment is funded by BIS National E-Infrastructure capital grant ST/K000373/1 and STFC DiRAC Operations grant ST/K0003259/1. DiRAC is part of the National E-Infrastructure. Continued access to the University of Hull's High Performance Computing Facility ('viper'), the HPC facility at the University of Central Lancashire and the computational facilities at Saint Mary's University are likewise gratefully acknowledged. TB was funded by the project grant 'The New Milky Way' from the Knut and Alice Wallenberg Foundation. SGS acknowledges the support by Fundacao para a Ciencia e Tecnologia (FCT) (ref: UID/FIS/04434/2013 & PTDC/FIS-AST/7073/2014 & Investigador FCT contract of reference IF/00028/2014) through national funds and by FEDER through COMPETE2020 (ref: POCI-01-0145-FEDER-007672 & POCI-01-0145-FEDER-016880). UH acknowledges support from the Swedish National Space Board (SNSB/Rymdstyrelsen). The Gaia-ESO Survey data products have been processed by the Cambridge Astronomy Survey Unit (CASU) at the Institute of Astronomy, University of Cambridge, and by the FLAMES/UVES reduction team at INAF/Osservatorio Astrofisico di Arcetri. These data have been obtained from the Gaia-ESO Survey Data Archive, prepared and hosted by the Wide Field Astronomy Unit, Institute for Astronomy, University of Edinburgh, which is funded by the UK Science and Technology Facilities Council. This work was partly supported by the European Union FP7 programme through ERC grant number 320360 and by the Leverhulme Trust through grant RPG-2012-541. We acknowledge the support from INAF and Ministero dell' Istruzione, dell' Universita' e della Ricerca (MIUR) in the form of the grant 'Premiale VLT 2012'. The results presented here benefit from discussions held during the Gaia-ESO workshops and conferences supported by the ESF (European Science Foundation) through the GREAT Research Network Programme. MTC acknowledge the financial support from the Spanish Ministerio de Economia y Competitividad, through grant AYA2013-40611-P. UH acknowledges support from the Swedish National Space Board (SNSB/Rymdstyrelsen). This work was supported by Sonderforschungsbereich SFB 881 'The Milky Way System' (subprojects A5, C9) of the German Research Foundation (DFG). This work benefited from discussions at GNASH workshop, Victoria supported by the National Science Foundation under Grant No. PHY-1430152 (JINA Center for the Evolution of the Elements). ARC is supported by Australian Research Council Grant DP160100637