Traces of the evolution of cosmic void galaxies: An Integral Field Spectroscopy based analysis

TL;DR

This study uses integral field spectroscopy data to compare galaxies in cosmic voids with those in denser regions, revealing that void galaxies tend to be younger and less metal-rich, supporting simulation predictions about their delayed evolution.

Contribution

The paper provides the first observational evidence supporting simulation predictions that void galaxies have younger stellar populations and different metallicity profiles compared to non-void galaxies.

Findings

Void galaxies are younger and less metal-rich.

No significant difference in gas mass across environments.

Age gradients are negative in both environments, with void galaxies being younger.

Abstract

Galaxies in the most underdense regions of the Universe, known as cosmic voids, exhibit astrophysical properties that suggest a distinct evolutionary path compared to galaxies in denser environments. Numerical simulations indicate that the assembly of void galaxies occurs later, leading to galaxies with younger stellar populations, low metallicities, and a high gas content in their halos, which provides the fuel to sustain elevated star formation activity. Our objective in this work is to test these numerical predictions with observational data by comparing galaxies in voids with galaxies in non-void environments. We used voids identified in SDSS data and galaxies from the MaNGA survey, which provides galaxies with integral field spectroscopy (IFS). We separated the galaxies into void and non-void samples, mimicked the magnitude distribution, and compared their integrated astrophysical properties as well as the metallicity and age profiles through a stacking technique, ETGs and LTGs separately. We find that void galaxies have younger and less metal-rich stellar populations. Regarding gas mass, we do not find differences across environments. When dividing galaxies into ETGs and LTGs, we observe that ETGs show negative gradients in both age and metallicity, with void galaxies consistently appearing younger and less metal-rich. For LTGs, age gradients are also negative, showing younger populations in void galaxies. However, we do not find statistically significant differences in stellar metallicity gradients between void and non-void environments. Our results show how the astrophysical properties of galaxies in voids differ from those of galaxies in the rest of the Universe. This suggests that the void environment plays a role in the evolution of its galaxies, delaying their assembly and growth.