The SDSS-UKIDSS Fundamental Plane of Early-type Galaxies

TL;DR

This study derives the Fundamental Plane relation for early-type galaxies using SDSS and UKIDSS data, showing its waveband independence and implications for galaxy properties and formation theories.

Contribution

It provides the first large, homogeneous analysis of the FP across optical and NIR bands, revealing minimal waveband dependence and insights into galaxy stellar populations.

Findings

FP coefficients increase by at most 8% from optical to NIR

FP tilt is not driven by stellar populations but by other effects

Massive galaxies are slightly more metal-rich and have synchronized ages

Abstract

We derive the Fundamental Plane (FP) relation for a sample of 1430 early-type galaxies in the optical (r band) and the near-infrared (K band), by combining SDSS and UKIDSS data. With such a large, homogeneous dataset, we are able to assess the dependence of the FP on the waveband. Our analysis indicates that the FP of luminous early-type galaxies is essentially waveband independent, with its coefficients increasing at most by 8% from the optical to the NIR. This finding fits well into a consistent picture where the tilt of the FP is not driven by stellar populations, but results from other effects, such as non-homology. In this framework, the optical and NIR FPs require more massive galaxies to be slightly more metal rich than less massive ones, and to have highly synchronized ages, with an age variation per decade in mass smaller than a few percent.