SPIDER - III. Environmental Dependence of the Fundamental Plane of Early-type Galaxies

• Published in: arXiv.org 2010-06
• Main Authors: La Barbera, F, Lopes, P A A, de Carvalho, R R, I G de la Rosa, Berlind, A A
• Format: Article
• Language: English
• Subjects: Age; Astronomical models; Density; Dependence; Galactic clusters; Galactic evolution; Galaxies; Luminosity; Metallicity; Milky Way Galaxy; Red shift; Star & galaxy formation; Stars & galaxies
• ISSN: 2331-8422
• DOI: 10.48550/arxiv.1003.1119

We analyse the Fundamental Plane (FP) relation of \(39,993\) early-type galaxies (ETGs) in the optical (griz) and \(5,080\) ETGs in the Near-Infrared (YJHK) wavebands, forming an optical\(+\)NIR sample of \(4,589\) galaxies. We focus on the analysis of the FP as a function of the environment where galaxies reside. We characterise the environment using the largest group catalogue, based on 3D data, generated from SDSS at low redshift (\(z < 0.1\)). We find that the intercept \(``c''\) of the FP decreases smoothly from high to low density regions, implying that galaxies at low density have on average lower mass-to-light ratios than their high-density counterparts. The \(``c''\) also decreases as a function of the mean characteristic mass of the parent galaxy group. However, this trend is weak and completely accounted for by the variation of \(``c''\) with local density. The variation of the FP offset is the same in all wavebands, implying that ETGs at low density have younger luminosity-weighted ages than cluster galaxies, consistent with the expectations of semi-analytical models of galaxy formation. We measure an age variation of \(\sim 0.048\)~dex (\(\sim 11\%\)) per decade of local galaxy density. This implies an age difference of about \(32 \%\) (\(\sim 3 \, Gyr\)) between galaxies in the regions of highest density and the field. We find the metallicity decreasing, at \(\sim 2\)~\(\sigma\), from low to high density. We also find \(2.5 \, \sigma\) evidence that the variation in age per decade of local density augments, up to a factor of two, for galaxies residing in massive relative to poor groups. (abridged)