Abstract
The growth of brightest cluster galaxies (BCGs) is closely related to the properties of their host cluster. We present evidence for dry mergers as the dominant source of BCG mass growth at z less than or similar to 1 in the XXL 100 brightest cluster sample. We use the global red sequence, H alpha emission and mean star formation history to show that BCGs in the sample possess star formation levels comparable to field ellipticals of similar stellar mass and redshift. XXL 100 brightest clusters are less massive on average than those in other X-ray selected samples such as LoCuSS or HIFLUGCS. Few clusters in the sample display high central gas concentration, rendering inefficient the growth of BCGs via star formation resulting from the accretion of cool gas. Using measures of the relaxation state of their host clusters, we show that BCGs grow as relaxation proceeds. We find that the BCG stellar mass corresponds to a relatively constant fraction 1 per cent of the total cluster mass in relaxed systems. We also show that, following a cluster scale merger event, the BCG stellar mass lags behind the expected value from the M-cluster-M-BCG relation but subsequently accretes stellar mass via dry mergers as the BCG and cluster evolve towards a relaxed state.
Item Type: | Journal article |
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Faculties: | Physics |
Subjects: | 500 Science > 530 Physics |
ISSN: | 0035-8711 |
Language: | English |
Item ID: | 47988 |
Date Deposited: | 27. Apr 2018, 08:14 |
Last Modified: | 04. Nov 2020, 13:25 |