The Calar Alto Legacy Integral Field Area Survey (CALIFA) is observing a statistically well-defined sample of ~600 galaxies in the local universe using 250 observing nights with the PMAS/PPAK integral field spectrophotometer, mounted on the Calar Alto 3.5 m telescope. CALIFA will make its reduced data public as soon as their quality as well as that of the data reduction pipeline has been verified.
Our survey will provide the largest and most comprehensive wide-field IFU survey of galaxies carried out to date, addressing fundamental issues in galaxy evolution. The two-dimensional spectral maps obtained for a large and well-defined sample will allow for example to 1) extend the kinematic classification of galaxies over the whole Hubble sequence using a homogeneous dataset, 2) study the ISM over entire galaxies and a large sample, which will yield new insights on the importance of AGN, star formation, shocks and old stars as ionization sources, 3) study stellar populations in the outskirts of disk galaxies to assess the importance of star formation vs. radial migration, 4) provide accurate aperture corrections for the much large single-fiber surveys, such as SDSS, 5) derive stellar population gradients in age and metallicity to constrain the formation mechanisms of early- and late-type galaxies alike. As the data become public, we expect more exciting science we have not thought about to emerge. CALIFA can also be viewed to provide a valuable bridge between large single-aperture surveys such as SDSS and more detailed studies of individual galaxies with PPAK (e.g: PINGS), SAURON, VIRUS-P, and other instruments.
Observations have started in summer 2010. The defining drivers for the observational setup of the project are: (a) derive the the stellar population content both in age and metallicity; (b) trace the distribution of ionized gas and estimate chemical abundances for the gas phase; (c) measure the kinematic properties, both from emission and from absorption lines; and (d) for all of the quantities create maps covering the entire luminous extent of the galaxies in the sample. We will thus map entire galaxies in their emission- and absorption-line properties in an unprecedented way.
The targets for this survey have been selected from the photometric catalog of the Sloan Digital Sky Survey as a sample limited in apparent isophotal diameter. CALIFA thus makes maximal use of the unique capabilities of the PMAS/PPAK instrument. PPAK offers a combination of extremely wide field-of-view (> 1 arcmin2) with a high filling factor in one single pointing (65%), good spectral resolution, and wavelength sensitivity across the optical spectrum. An additional selection criterion is the covered redshift range to 0.005 < z < 0.03, which ensures that all galaxies can be observed with the same grating settings and we still obtain the same physical information. The spectra cover the range 3700-7000 AA in two overlapping setups, one in the red (4300-7000 AA) at a spectral resolution of R=850 and one in the blue (3700-5000 AA) at R~1650, where the resolutions quoted are those at the overlapping wavelength range (lambda~4500 A).
In summary, we hope that CALIFA will become a true legacy survey with lasting value for the study of galaxies in the local universe.
More detailed information about the project can be found in the so-called CALIFA's RED BOOK.
