Abstract
Minor mergers are thought to be responsible for the size growth of quiescent field galaxies with decreasing redshift. We test this hypothesis using the cluster environment as a laboratory. Satellite galaxies in clusters move at high velocities, making mergers between them rare. The stellar mass-size relation in 10 clusters and in the field is measured and compared at z ∼ 1. Our cluster sample contains 344 spectroscopically confirmed cluster members with Gemini/Gemini Multi-Object Spectrographs and 182 confirmed with Hubble Space Telescope/Wide Field Camera 3 G141 grism spectroscopy. On average, quiescent and star-forming cluster galaxies are smaller than their field counterparts by (0.08 ± 0.04) and (0.07 ± 0.01) dex, respectively. These size offsets are consistent with the average sizes of quiescent and star-forming field galaxies between 1.2 = z = 1.5, implying the cluster environment has inhibited size growth between this period and z ∼ 1. The negligible differences measured between the z ∼ 0 field and cluster quiescent mass-size relations in other works imply that the average size of quiescent cluster galaxies must rise with decreasing redshift. Using a toy model, we show that the disappearance of the compact cluster galaxies might be explained if, on average, ∼40 per cent of them merge with their brightest cluster galaxies (BCGs) and ∼60 per cent are tidally destroyed into the intracluster light (ICL) between 0 = z = 1. This is in agreement with the observed stellar mass growth of BCGs between 0 = z = 1 and the observed ICL stellar mass fraction at z ∼ 0. Our results support minor mergers as the cause for the size growth in quiescent field galaxies, with cluster-specific processes responsible for the similarity between the field and cluster quiescent mass-size relations at low redshift.
Original language | English (US) |
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Pages (from-to) | 595-617 |
Number of pages | 23 |
Journal | Monthly Notices of the Royal Astronomical Society |
Volume | 484 |
Issue number | 1 |
DOIs | |
State | Published - Mar 21 2019 |
Externally published | Yes |
Keywords
- Galaxies: clusters: general
- Galaxies: evolution
- Galaxies: high-redshift
- Galaxies: star formation
- Galaxies: stellar content
ASJC Scopus subject areas
- Astronomy and Astrophysics
- Space and Planetary Science