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The effects of spatial resolution on integral field spectrograph surveys at different redshifts − The CALIFA perspective

D. Mast, F. F. Rosales-Ortega, S. F. Sánchez, J. M. Vílchez, J. Iglésias-Páramo, C. J. Walcher, B. Husemann, I. Márquez, R. A. Marino, R. C Kennicutt, A. Monreal-Ibero, L. Galbany, A. de Lorenzo-Cáceres, J. Méndez-Abreu, C. Kehrig, A. del Olmo, M. Relaño, L. Wisotzki, E. Mármol-Queraltó, S. Bekeraitè, P. Papaderos, V. Wild, J. A. L. Aguerri, J. Falcón-Barroso, D. J. Bomans, B. Ziegler, B. García-Lorenzo, J. Bland-Hawthorn, Á. R. López-Sánchez, G. van de Ven

Abstract
Context. Over the past decade, 3D optical spectroscopy has become the preferred tool for understanding the properties of galaxies and is now increasingly used to carry out galaxy surveys. Low redshift surveys include SAURON, DiskMass, ATLAS3D, PINGS, and VENGA. At redshifts above 0.7, surveys such as MASSIV, SINS, GLACE, and IMAGES have targeted the most luminous galaxies to study mainly their kinematic properties. The on-going CALIFA survey (z ~ 0.02) is the first of a series of upcoming integral field spectroscopy (IFS) surveys with large samples representative of the entire population of galaxies. Others include SAMI and MaNGA at lower redshift and the upcoming KMOS surveys at higher redshift. Given the importance of spatial scales in IFS surveys, the study of the effects of spatial resolution on the recovered parameters becomes important.
Aims. We explore the capability of the CALIFA survey and a hypothetical higher redshift survey to reproduce the properties of a sample of objects observed with better spatial resolution at lower redshift.
Methods. Using a sample of PINGS galaxies, we simulated observations at different redshifts. We then studied the behaviour of different parameters as the spatial resolution degrades with increasing redshift.
Results. We show that at the CALIFA resolution, we are able to measure and map common observables in a galaxy study: the number and distribution of H ii regions (Hα  flux structure), the gas metallicity (using the O3N2 method), the gas ionization properties (through the [N ii]/Hα  and [O iii]/Hβ  line ratios), and the age of the underlying stellar population (using the D4000 index). This supports the aim of the survey to characterise the observable properties of galaxies in the Local Universe. Our analysis of simulated IFS data cubes at higher redshifts highlights the importance of the projected spatial scale per spaxel as the most important figure of merit in the design of an integral field survey.

Keywords
techniques: spectroscopic – galaxies: abundances – stars: formation – galaxies: ISM – galaxies: stellar content

Astronomy and Astrophysics
Volume 561, Number of pages A129_1
2014 January

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Instituto de Astrofísica e Ciências do Espaço Universidade do Porto Faculdade de Ciências da Universidade de Lisboa
Fundação para a Ciência e a Tecnologia COMPETE 2020 PORTUGAL 2020 União Europeia