SDSS-IV MaNGA: Spatially resolved star-formation histories and the connection to galaxy physical properties

TL;DR

This study uses spatially resolved spectroscopy from SDSS-IV MaNGA to analyze star formation histories across different galaxy types and masses, revealing inside-out growth and quenching patterns, and the influence of morphology and interactions.

Contribution

It provides a detailed spatial analysis of star formation histories in thousands of galaxies, highlighting the dependence on stellar mass and morphology, and the role of interactions in triggering starbursts.

Findings

Star formation distribution depends mainly on stellar mass.

High-mass galaxies show inside-out growth and quenching.

Starburst regions are more common in asymmetric galaxies and outskirts.

Abstract

A key task of observational extragalactic astronomy is to determine where -- within galaxies of diverse masses and morphologies -- stellar mass growth occurs, how it depends on galaxy properties and what processes regulate star formation. Using spectroscopic indices derived from the stellar continuum at $\sim 4000$\AA, we determine the spatially resolved star-formation histories of 980000 spaxels in 2404 galaxies in the SDSS-IV MaNGA IFU survey. We examine the spatial distribution of star-forming, quiescent, green valley, starburst and post-starburst spaxels as a function of stellar mass and morphology to see where and in what types of galaxy star formation is occurring. The spatial distribution of star-formation is dependent primarily on stellar mass, with a noticeable change in the distribution at \mstar$>10^{10}$\msun. Galaxies above this mass have an increasing fraction of regions that are forming stars with increasing radius, whereas lower mass galaxies have a constant fraction of star forming regions with radius. Our findings support a picture of inside-out growth and quenching at high masses. We find that morphology (measured via concentration) correlates with the fraction of star-forming spaxels, but not with their radial distribution. We find (post-)starburst regions are more common outside of the galaxy centre, are preferentially found in asymmetric galaxies, and have lower gas-phase metallicity than other regions, consistent with interactions triggering starbursts and driving low metallicity gas into regions at $<1.5R_e$.