Integral field spectroscopy of a sample of nearby galaxies
I. Sample, observations, and data reduction ⋆
Centro Astronómico Hispano Alemán, Calar Alto, (CSIC-MPG), C/Jesús
Durbán Remón 2-2, 04004
2 Departamento de Astrofísica y CC. de la Atmósfera, Universidad Complutense de Madrid, 28040- Madrid, Spain
3 Instituto de Astrofísica de Andalucía (CSIC), Camino Bajo de Huetor s/n, Aptdo. 3004, 18080 - Granada, Spain
4 Centro de Estudios de Física del Cosmos de Aragón (CEFCA), C/ Pizarro 1, 3 a, 41001 Teruel, Spain
5 Departamento de Física Teórica, Universidad Autóoma de Madrid, 28049 - Cantoblanco, Madrid, Spain
Received: 5 April 2011
Accepted: 17 June 2011
Aims. Integral field spectroscopy (IFS) is a powerful approach to studying nearby galaxies since it enables a detailed analysis of their resolved physical properties. Here we present our study of a sample of nearby galaxies selected to exploit the two-dimensional information provided by the IFS.
Methods. We observed a sample of 48 galaxies from the local universe with the PPaK integral field spectroscopy unit (IFU), of the PMAS spectrograph, mounted at the 3.5 m telescope at Calar Alto Observatory (Almeria, Spain). Two different setups were used during these studies (low – V300 – and medium – V600 – resolution mode) covering a spectral range of around 3700–7000 ÅÅ. We developed a full automatic pipeline for the data reduction, which includes an analysis of the quality of the final data products. We applied a decoupling method to obtain the ionised gas and stellar content of these galaxies, and derive the main physical properties of the galaxies. To assess the accuracy in the measurements of the different parameters, we performed a set of simulations to derive the expected relative errors obtained with these data. In addition, we extracted spectra for two types of aperture, one central and another integrated over the entire galaxy, from the datacubes. The main properties of the stellar populations and ionised gas of these galaxies and an estimate of their relative errors are derived from those spectra, as well as from the whole datacubes.
Results. We compare the central spectrum extracted from our datacubes and the SDSS spectrum for each of the galaxies for which this is possible, and find close agreement between the derived values for both samples. We find differences on the properties of galaxies when comparing a central and an integrated spectra, showing the effects of the extracted aperture on the interpretation of the data. Finally, we present two-dimensional maps of some of the main properties derived with the decoupling procedure.
Key words: surveys / techniques: spectroscopic / galaxies: abundances / stars: formation / galaxies: ISM / galaxies: stellar content
© ESO, 2011