Red riding on hood: Exploring how galaxy colour depends on environment
Bhambhani, Baldry, Brough, Hill et al. 2023, MNRAS, in press.
(link: ADS)
Abstract
Galaxy populations are known to exhibit a strong colour bimodality,
corresponding to blue star-forming and red quiescent subpopulations.
The relative abundance of the two populations has been found to vary
with stellar mass and environment. In this paper, we explore the effect
of environment considering different types of measurements. We choose a
sample of 49,911 galaxies with 0.05 < z < 0.18 from the Galaxy And
Mass Assembly survey. We study the dependence of the fraction of red
galaxies on different measures of the local environment as well as the
large-scale "geometric" environment defined by density gradients in the
surrounding cosmic web. We find that the red galaxy fraction varies with
the environment at fixed stellar mass. The red fraction depends more
strongly on local environmental measures than on large-scale geometric
environment measures. By comparing the different environmental
densities, we show that no density measurement fully explains the
observed environmental red fraction variation, suggesting the different
measures of environmental density contain different information. We test
whether the local environmental measures, when combined together, can
explain all the observed environmental red fraction variation. The
geometric environment has a small residual effect, and this effect is
larger for voids than any other type of geometric environment. This
could provide a test of the physics applied to cosmological-scale galaxy
evolution simulations as it combines large-scale effects with local
environmental impact.
Data:
GAMA sample with v-max values and multiple environmental measurements 0.04 < z < 0.18:
Description File,
CSV data file.
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