The void galaxy survey: photometry, structure and identity of void galaxies

Abstract

We analyze photometry from deep B-band images of 59 void galaxies in the Void Galaxy Survey (VGS), together with their near-infrared 3.6µm and 4.5µm Spitzer photometry. The VGS galaxies constitute a sample of void galaxies that were selected by a geometric-topological procedure from the SDSS DR7 data release, and which populate the deep interior of voids. Our void galaxies span a range of absolute Bmagnitude from M B = −15.5 to M B = −20, while at the 3.6µm band their magnitudes range from M 3.6 = −18 to M 3.6 = −24. Their B-[3.6] colour and structural parameters indicate these are star forming galaxies. A good reflection of the old stellar population, the near-infrared band photometry also provide a robust estimate of the stellar mass, which for the VGS galaxies we confirm to be smaller than 3 × 10 10 M . In terms of the structural parameters and morphology, our findings align with other studies in that our VGS galaxy sample consists mostly of small late-type galaxies. Most of them are similar to Sd-Sm galaxies, although a few are irregularly shaped galaxies. The sample even includes two early-type galaxies, one of which is an AGN. Their Sérsic indices are nearly all smaller than n = 2 in both bands and they also have small half-light radii. In all, we conclude that the principal impact of the void environment on the galaxies populating them mostly concerns their low stellar mass and small size.

The density of dark matter haloes of early-type galaxies in low-density environments

“…6, bottom panel). Without trying to over interpret these results given the fact the general galaxy population in voids consists of mostly small late-type spirals and massive ETGs are very rare (Croton et al 2005;Beygu et al 2017), the above findings suggest that DM haloes of ETGs are less dense when these objects live in low-density regions, even if more extended kinematic data are needed to confirm this, given the large errors affecting our DM densities. The same remark applies to the reported DM fractions, which are similar to the ones derived for cluster ETGs (see Table 5).…”

Stellar Mass Profiles of Quiescent Galaxies in Different Environments at z ∼ 0

“…In this study, we explored the properties of the isolated quiescent galaxies in the void environments. Previous works have already shown that void galaxies tend to be bluer and have a statistically higher fraction of the late-type galaxies compared to the average galaxy environments (e.g., Rojas et al 2004Rojas et al , 2005Hoyle et al 2012;Kreckel et al 2012;Liu et al 2015;Beygu et al 2017). We have shown that the total fraction of the quiescent galaxies in the void regions is about ∼ 18% down to a limiting magnitude of -19 in the r-band, and the fraction of the isolated quiescent ones is ∼ 14%.…”

Probing Galaxy assembly bias in BOSS galaxies using void probabilities

“…Voids also present a useful probe to understand the nature of galaxy formation. It is known that galaxies found in voids are typically spiral/irregularly-shaped and found to be HI rich, having low luminosity and stellar mass, and small size relative to the general population of galaxies (Tavasoli et al 2015, Beygu et al 2017, and Pustilnik et al 2019). This suggests that galaxy formation and evolution may have a dependence on the large scale dark matter density.…”