Volume 639, July 2020
|Number of page(s)||11|
|Section||Cosmology (including clusters of galaxies)|
|Published online||09 July 2020|
Properties of brightest group galaxies in cosmic web filaments
Tartu Observatory University of Tartu, Observatooriumi 1, 61602 Tõravere, Estonia
2 Tuorla Observatory, Department of Physics and Astronomy, University of Turku, Vesilinnantie 5, 20014 Turku, Finland
Accepted: 14 May 2020
Context. The cosmic web, a complex network of galaxy groups and clusters connected by filaments, is a dynamical environment in which galaxies form and evolve. However, the impact of cosmic filaments on the properties of galaxies is difficult to study because of the much more influential local (galaxy-group scale) environment.
Aims. The aim of this paper is to investigate the dependence of intrinsic galaxy properties on distance to the nearest cosmic web filament, using a sample of galaxies for which the local environment is easily assessable.
Methods. Our study is based on a volume-limited galaxy sample with Mr ≤ −19 mag, drawn from the SDSS DR12. We chose brightest group galaxies (BGGs) in groups with two to six members as our probes of the impact of filamentary environment because their local environment can be determined more accurately. We use the Bisous marked point process method to detect cosmic-web filaments with radii of 0.5−1.0 Mpc and measure the perpendicular filament spine distance (Dfil) for the BGGs. We limit our study to Dfil values up to 4 Mpc. We use the luminosity density field as a tracer of the local environment. To achieve uniformity of the sample and to reduce potential biases we only consider filaments longer than 5 Mpc. Our final sample contains 1427 BGGs.
Results. We note slight deviations between the galaxy populations inside and outside the filament radius in terms of stellar mass, colour, the 4000 Å break, specific star formation rates, and morphologies. However, all these differences remain below 95% confidence and are negligible compared to the effects arising from local environment density.
Conclusions. Within a 4 Mpc radius of the filament axes, the effect of filaments on BGGs is marginal. The local environment is the main factor in determining BGG properties.
Key words: galaxies: general / galaxies: statistics / galaxies: evolution / galaxies: groups: general / large-scale structure of Universe
© ESO 2020
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