Spheroid's Panchromatic Investigation in Different Environmental Regions (SPIDER) - I. Sample and galaxy parameters in the grizYJHK wavebands

TL;DR

This study provides a comprehensive panchromatic analysis of early-type galaxies, examining their photometric and structural properties across multiple wavebands, and compares measurement techniques to establish reliable parameters for galaxy scaling relations.

Contribution

It introduces a homogeneous method for deriving galaxy parameters across grizYJHK bands and compares different measurement techniques, enhancing the accuracy of galaxy property analysis.

Findings

Color gradients influence the mass-metallicity relation in ETGs.

Effective radius decreases by ~30% from g to K band.

Significant differences found between measurement methods.

Abstract

This is the first paper of a series presenting a Spheroid's Panchromatic Investigation in Different Environmental Regions (SPIDER). The sample of spheroids consists of 5,080 bright (Mr<-20) Early-Type galaxies (ETGs), in the redshift range of 0.05 to 0.095, with optical (griz) photometry and spectroscopy from SDSS-DR6 and Near-Infrared (YJHK) photometry from UKIDSS-LAS (DR4). We describe how homogeneous photometric parameters (galaxy colors and structural parameters) are derived using grizYJHK wavebands. We find no systematic steepening of the CM relation when probing the baseline from g-r to g-K, implying that internal color gradients drive most of the mass-metallicity relation in ETGs. As far as structural parameters are concerned we find that the mean effective radius of ETGs smoothly decreases, by ~30%, from g through K, while no significant dependence on waveband is detected for the axis ratio, Sersic index, and a4 parameters. Also, velocity dispersions are re-measured for all the ETGs using STARLIGHT and compared to those obtained by SDSS. We compare our (2DPHOT) measurements of total magnitude, effective radius, and mean surface brightness with those obtained as part of the SDSS pipeline (Photo). Significant differences are found and reported, including comparisons with a third and independent part. A full characterization of the sample completeness in all wavebands is presented, establishing the limits of application of the characteristic parameters presented here for the analysis of the global scaling relations of ETGs.