University of Hertfordshire

From the same journal

From the same journal

By the same authors

  • N.~R. Bonaventura
  • T.~M.~A. Webb
  • A. Muzzin
  • A. Noble
  • C. Lidman
  • G. Wilson
  • H.~K.~C. Yee
  • J. Geach
  • Y. Hezaveh
  • D. Shupe
  • J. Surace
View graph of relations
Original languageEnglish
Number of pages23
Pages (from-to)1259-1281
JournalMonthly Notices of the Royal Astronomical Society
Journal publication date1 Aug 2017
Volume469
Issue2
Early online date24 Mar 2017
DOIs
Publication statusPublished - 1 Aug 2017

Abstract

We present the results of a Spitzer/Herschel infrared photometric analysis of the largest (716) and the highest-redshift (z = 1.8) sample of brightest cluster galaxies (BCGs), those from the Spitzer Adaptation of the Red-Sequence Cluster Survey Given the tension that exists between model predictions and recent observations of BCGs at z < 2, we aim to uncover the dominant physical mechanism(s) guiding the stellar mass buildup of this special class of galaxies, the most massive in the Universe and uniquely residing at the centres of galaxy clusters. Through a comparison of their stacked, broad-band, infrared spectral energy distributions (SEDs) to a variety of model templates in the literature, we identify the major sources of their infrared energy output, in multiple redshift bins between 0 < z < 1.8. We derive estimates of various BCG physical parameters from the stacked νLν SEDs, from which we infer a star-forming, as opposed to a ‘red and dead’ population of galaxies, producing tens to hundreds of solar masses per year down to z = 0.5. This discovery challenges the accepted belief that BCGs should only passively evolve through a series of gas-poor, minor mergers since z ∼ 4, but agrees with an improved semi-analytic model of hierarchical structure formation that predicts star-forming BCGs throughout the epoch considered. We attribute the star formation inferred from the stacked infrared SEDs to both major and minor ‘wet’ (gas-rich) mergers, based on a lack of key signatures (to date) of cooling-flow-induced star formation, as well as a number of observational and simulation-based studies that support this scenario.

Notes

© 2017 The Authors. Published by Oxford University Press on behalf of the Royal Astronomical Society

ID: 16294170