CALIFA, the Calar Alto Legacy Integral Field Area survey

I. Survey presentation^⋆

¹ Centro Astronómico Hispano Alemán, Calar Alto, (CSIC-MPG), C/Jesús Durbán Remón 2-2, 04004 Almeria, Spain
e-mail: sanchez@caha.es
² Institute of Astronomy, University of Cambridge, Madingley Road, Cambridge CB3 0HA, UK
³ Departamento de Astrofísica y CC. de la Atmósfera, Universidad Complutense de Madrid, Madrid 28040, Spain
⁴ Max Planck Institute for Astronomy, Königstuhl 17, 69117 Heidelberg, Germany
⁵ Instituto de Astrofísica de Andalucía (CSIC), Camino Bajo de Huetor, s/n, 18008, Granada, Spain
⁶ Leibniz-Institut für Astrophysik Potsdam (AIP), An der Sternwarte 16, 14482 Potsdam, Germany
⁷ Sydney Institute for Astronomy, School of Physics A28, University of Sydney, 2006 NSW, Australia
⁸ Australian Astronomical Observatory, PO BOX 296, Epping, 1710 NSW, Australia
⁹ Instituto de Astrofísica de Canarias (IAC), Glorieta de la Astronomía S/N, La Laguna, S/C de Tenerife, Spain
¹⁰ Departamento de Fisica Teorica, Universidad Autonoma de Madrid, Cantoblanco, 28049 Madrid, Spain
¹¹ Kapteyn Astronomical Institute, University of Groningen, 9700 AV, Groningen, The Netherlands
¹² Instituto de Física de Cantabria, CSIC-UC, Avenida de los Castros S/N, 39005 Santander, Spain
¹³ ZAH, Landessternwarte, Königstuhl 12, 69117 Heidelberg, Germany
¹⁴ Dark Cosmology Centre, Niels Bohr Institute, University of Copenhagen, Juliane Maries Vej 30, 2100 Copenhagen, Denmark
¹⁵ Centro de Astrofísica and Faculdade de Ciências, Universidade do Porto, Rua das Estrelas, 4150-762 Porto, Portugal
¹⁶ Astronomical Institute of the Academy of Sciences of the Czech Republic, v.v.i., Bocni II 1401, 14131 Prague, Czech Republic
¹⁷ CENTRA - Centro Multidisciplinar de Astrofísica, Instituto Superior Técnico, Av. Rovisco Pais 1, 1049-001 Lisbon, Portugal
¹⁸ SUPA, Institute for Astronomy, University of Edinburgh, Royal Observatory, Blackford Hill, Edinburgh EH9 3HJ, UK
¹⁹ Laboratoire d’Astropysique de Marseille, UMR 6110 CNRS, 38 rue F. Joliot-Curie, 13388 Marseille, France
²⁰ Department of Systems Engineering and Computing, University of Zaragoza, Teruel 44003, Spain
²¹ Department of Electronic Engineeing and Communications, University of Zaragoza, Teruel 44003, Spain
²² University of Vienna, Türkenschanzstrasse 17, 1180 Vienna, Austria
²³ Department of Physics and Astronomy, Macquarie University, NSW   2109, Australia
²⁴ Centro de Estudios de Física del Cosmos de Aragón (CEFCA), C/ G. Pizarro, 1, Teruel, Spain
²⁵ Astronomical Institute of the Ruhr-University Bochum Universitaetsstr. 150, 44801 Bochum, Germany
²⁶ Department of Physics, University of Missouri-Kansas City, Kansas City, MO 64110, USA
²⁷ Dep. Fŋsica Terica y del Cosmos, Campus de Fuentenueva, Universidad de Granada, 18071 Granada, Spain
²⁸ Depto. Astrofisica, Universidad de La Laguna (ULL), 38206 La Laguna, Tenerife, Spain
²⁹ Astronomisches Rechen Institut, Zentrum fuer Astronomie der Universitaet Heidelberg, Moenchhofstrasse 12–14, 69120 Heidelberg, Germany
³⁰ Institut d’Astrophysique de Paris, CNRS, 98bis Boulevard Arago, 75014 Paris, France
³¹ Laboratoire GEPI, Observatoire de Paris, CNRS-UMR8111, Univ. Paris-Diderot, 5 place Jules Janssen, 92195 Meudon, France
³² Tianjin Astrophysics Center, Tianjin Normal University, 300387 Tianjin, PR China
³³ Astronomical Institute, Faculty of Mathematics and Physics, Charles University in Prague, Ke Karlovu 3, 121 16 Prague, Czech Republic
³⁴ Dept. of Theoretical Physics and Astrophysics, Faculty of Science, Masaryk University, Kotlářská 2, 611 37 Brno, Czech Republic

Received: 27 May 2011
Accepted: 3 November 2011

Abstract

The final product of galaxy evolution through cosmic time is the population of galaxies in the local universe. These galaxies are also those that can be studied in most detail, thus providing a stringent benchmark for our understanding of galaxy evolution. Through the huge success of spectroscopic single-fiber, statistical surveys of the Local Universe in the last decade, it has become clear, however, that an authoritative observational description of galaxies will involve measuring their spatially resolved properties over their full optical extent for a statistically significant sample. We present here the Calar Alto Legacy Integral Field Area (CALIFA) survey, which has been designed to provide a first step in this direction. We summarize the survey goals and design, including sample selection and observational strategy. We also showcase the data taken during the first observing runs (June/July 2010) and outline the reduction pipeline, quality control schemes and general characteristics of the reduced data.

This survey is obtaining spatially resolved spectroscopic information of a diameter selected sample of  ~600 galaxies in the Local Universe (0.005 < z < 0.03). CALIFA has been designed to allow the building of two-dimensional maps of the following quantities: (a) stellar populations: ages and metallicities; (b) ionized gas: distribution, excitation mechanism and chemical abundances; and (c) kinematic properties: both from stellar and ionized gas components. CALIFA uses the PPAK integral field unit (IFU), with a hexagonal field-of-view of  ~1.3⎕′, with a 100% covering factor by adopting a three-pointing dithering scheme. The optical wavelength range is covered from 3700 to 7000 Å, using two overlapping setups (V500 and V1200), with different resolutions: R ~ 850 and R ~ 1650, respectively. CALIFA is a legacy survey, intended for the community. The reduced data will be released, once the quality has been guaranteed.

The analyzed data fulfillthe expectations of the original observing proposal, on the basis of a set of quality checks and exploratory analysis: (i) the final datacubes reach a 3σ limiting surface brightness depth of  ~23.0 mag/arcsec² for the V500 grating data (~22.8 mag/arcsec² for V1200); (ii) about  ~70% of the covered field-of-view is above this 3σ limit; (iii) the data have a blue-to-red relative flux calibration within a few percent in most of the wavelength range; (iv) the absolute flux calibration is accurate within  ~8%with respect to SDSS; (v) the measured spectral resolution is  ~85 km s^-1 for V1200 (~150 km s^-1 for V500); (vi) the estimated accuracy of the wavelength calibration is  ~5 km s^-1 for the V1200 data (~10 km s^-1 for the V500 data); (vii) the aperture matched CALIFA and SDSS spectra are qualitatively and quantitatively similar. Finally, we show that we are able to carry out all measurements indicated above, recovering the properties of the stellar populations, the ionized gas andthe kinematics of both components. The associated maps illustrate the spatial variation of these parameters across the field, reemphasizing the redshift dependence of single aperture spectroscopic measurements. We conclude from this first look at the data that CALIFA will be an important resource for archaeological studies of galaxies in the Local Universe.