Massive Galaxies Are Larger in Dense Environments: Environmental Dependence of Mass-Size Relation of Early-type Galaxies
Abstract
Under the Λ cold dark matter (ΛCDM) cosmological models, massive galaxies are expected to be larger in denser environments through frequent hierarchical mergers with other galaxies. Yet, observational studies of low-redshift early-type galaxies have shown no such trend, standing as a puzzle to solve during the past decade. We analyzed 73,116 early-type galaxies at 0.1 ≤ z < 0.15, adopting a robust nonparametric size measurement technique and extending the analysis to many massive galaxies. We find for the first time that local early-type galaxies heavier than 1011.2 M⊙ show a clear environmental dependence in mass-size relation, in such a way that galaxies are as much as 20%-40% larger in the densest environments than in underdense environments. Splitting the sample into the brightest cluster galaxies (BCGs) and non-BCGs does not affect the result. This result agrees with the ΛCDM cosmological simulations and suggests that mergers played a significant role in the growth of massive galaxies in dense environments as expected in theory.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- January 2017
- DOI:
- 10.3847/1538-4357/834/1/73
- arXiv:
- arXiv:1612.07945
- Bibcode:
- 2017ApJ...834...73Y
- Keywords:
-
- galaxies: elliptical and lenticular;
- cD;
- galaxies: evolution;
- galaxies: formation;
- galaxies: statistics;
- galaxies: structure;
- Astrophysics - Astrophysics of Galaxies
- E-Print:
- 27 pages, 29 figures, 4 tables, accepted for publication in the ApJ