Spectral synthesis of stellar populations in the 3D era: The CALIFA experience

TL;DR

This paper demonstrates how spectral synthesis of 3D galaxy data-cubes from CALIFA enhances understanding of stellar populations, revealing detailed internal galaxy properties and relations like metallicity evolution and star formation laws.

Contribution

It introduces a method for applying spectral synthesis to 3D galaxy data, providing new insights into internal galaxy physics and evolution.

Findings

Evolution of mass-metallicity relations

Comparison of star formation rate indicators

Star formation rate correlates with dust optical depth

Abstract

Methods to recover the fossil record of galaxy evolution encoded in their optical spectra have been instrumental in processing the avalanche of data from mega-surveys along the last decade, effectively transforming observed spectra onto a long and rich list of physical properties: from stellar masses and mean ages to full star formation histories. This promoted progress in our understanding of galaxies as a whole. Yet, the lack of spatial resolution introduces undesirable aperture effects, and hampers advances on the internal physics of galaxies. This is now changing with 3D surveys. The mapping of stellar populations in data-cubes allows us to figure what comes from where, unscrambling information previously available only in integrated form. This contribution uses our starlight-based analysis of 300 CALIFA galaxies to illustrate the power of spectral synthesis applied to data-cubes. The selected results highlighted here include: (a) The evolution of the mass-metallicity and mass-density-metallicity relations, as traced by the mean stellar metallicity. (b) A comparison of star formation rates obtained from H{\alpha} to those derived from full spectral fits. (c) The relation between star formation rate and dust optical depth within galaxies, which turns out to mimic the Schmidt-Kennicutt law. (d) PCA tomography experiments.