EAS2024
We categorise a sample of 9620 galaxies into the three primary large scale structures (voids, filaments and walls, and clusters) and further classify them based on their local environment (as either "singlets" or group members), through a search of companion galaxies within projected distances less than 450 kpc and velocity differences below 160 km/s, which constitute criteria for physical bounding according to previous studies. Subsequently, we explore these subsamples, classified environment-wise, through SFH data from previous works. Throughout the study, we additionally explore subsamples classified in terms of the SFH bimodality, which finds two differentiated types of galaxies: long timescale SFH galaxies (LT-SFH), that assemble their mass steadily along cosmic time, and short-timescale SFH galaxies (ST-SFH), which form their stars early and rapidly. We compare formation look-back times, understood as the time from when a galaxy formed a given percentage of its mass.
Mass assembly look-back times are generally larger for galaxies in groups, particularly in ST-SFH galaxies in voids. The distributions of look-back times in ST-SFH galaxies are statistically different for singlets and groups, although significant differences are not found in LT-SFH galaxies. When studying look-back time distributions with respect to stellar mass, we find that the large-scale environment is able to cause a delay in mass assembly of up to ~2 Gyr, while this delay is <1 Gyr in the case of local environment. The effect of both environments is more significant in less massive galaxies, and in LT-SFHs. Our results are consistent with galaxies in groups assembling their mass earlier than singlets, especially in voids. The opposite result is found only in high mass void galaxies, revealing the different upbringing of central galaxies. Nevertheless, the effect of local environment appears to be undermined by the influence of the dominating large scale environment. Additionally, we find that local environment is not a possible driving mechanism of the SFH bimodality.