Insights into formation scenarios of massive early-type galaxies from spatially resolved stellar population analysis in CALIFA. (2020)
Keywords :
techniques imaging spectroscopy - galaxies: abundances - galaxies: elliptical and lenticular, cD - galaxies: stellar content
Abstract:We perform spatially resolved stellar population analysis for a sample of 69 early-type galaxies (ETGs) from the CALIFA integral field spectroscopic survey, including 48 ellipticals and 21 S0's. We generate and quantitatively characterize profiles of light-weighted mean stellar age and metallicity within <~2Re, as a function of radius and stellar-mass surface density {mu}*. We study in detail the dependence of profiles on galaxies' global properties, including velocity dispersion {sigma}_e_, stellar mass, morphology. ETGs are universally characterized by strong, negative metallicity gradients (~-0.3dex per Re) within 1Re, which flatten out moving towards larger radii. A quasi-universal local {mu}*-metallicity relation
...(more)
This study is based on a sample of 69 ETGs drawn from the main
diameter-selected sample of the Calar Alto Legacy Integral Field Area
(CALIFA) survey (Sanchez et al., 2012A&A...538A...8S; Walcher et al.,
2014A&A...569A...1W) in its third and final data release (Sanchez et
al., 2016, Cat. J/A+A/594/A36, DR3). These galaxies are selected from
the seventh data release of the Sloan Digital Sky Survey (Abazajian et
al., 2009ApJS..182..543A) requiring isophotal r-band diameter
45-arcsec<isoA_r_<79.2-arcsec, r-band Petrosian magnitude <20 and
available redshift 0.005<z<0.03.
Galaxies are observed in integral-field spectroscopy at the 3.5m
telescope of the Calar Alto observatory with the Potsdam
Multi-Aperture Spectrograph, PMAS in the PPAK mode. The hexagonal
field of view of 74 arcsec x 64 arcsec is covered by a bundle of
331 science fibres, in three dithers.
Out of the 542 observed main sample galaxies, we consider only the 394
galaxies that have been observed in both the blue 'V1200' and red
'V500' setups. The unvignetted spectral coverage extends from 3700
to 7140{AA}, with a spatial sampling of 1 arcsec per spaxel
(effective spatial resolution ~2.57 arcsec FWHM).
From this sample we select morphologically classified ETGs, i.e.
galaxies with morphological type earlier than S0a (S0a excluded), not
classified as mergers (see Walcher et al., 2014A&A...569A...1W). After
visual inspection we further discard three galaxies that are
misclassified later types than E or S0.
Parameters of stellar population profiles, gradients and their
correlations with global parameters for 69 ETGs observed in CALIFA.
See reference paper (incl. online appendices) for a detailed
description of measurements and model used for inferences.
Stefano Zibetti, stefano.zibetti(at)inaf.it
