CALIFA survey: The spatially resolved star formation history of massive galaxies

TL;DR

The CALIFA survey uses spatially resolved spectroscopy to analyze how massive galaxies form and evolve, revealing inside-out growth patterns and the influence of local density on galaxy evolution.

Contribution

This study is the first to spatially resolve the star formation history of galaxies across the color-magnitude diagram using spectral synthesis techniques.

Findings

Galaxies generally grow inside-out, except at the lowest masses.

Growth rates vary with galaxy mass, peaking at intermediate masses.

Age radial gradients correlate with stellar mass density.

Abstract

The Calar Alto Legacy Integral Field Area (CALIFA) is an ongoing 3D spectroscopic survey of 600 nearby galaxies of all kinds. This pioneer survey is providing valuable clues on how galaxies form and evolve. Processed through spectral synthesis techniques, CALIFA datacubes allow us to, for the first time, spatially resolve the star formation history of galaxies spread across the color-magnitude diagram. The richness of this approach is already evident from the results obtained for the first 107 galaxies. Here we show how the different galactic spatial sub-components ("bulge" and "disk") grow their stellar mass over time. We explore the results stacking galaxies in mass bins, finding that, except at the lowest masses, galaxies grow inside-out, and that the growth rate depends on a galaxy's mass. The growth rate of inner and outer regions differ maximally at intermediate masses. We also find a good correlation between the age radial gradient and the stellar mass density, suggesting that the local density is a main driver of galaxy evolution.