Exploring the progenitors of brightest cluster galaxies at z ∼ 2

Zhao, Dongyao and Conselice, Christopher J. and Aragón-Salamanca, Alfonso and Almaini, Omar and Hartley, William G. and Lani, Caterina and Mortlock, Alice and Old, Lyndsay (2017) Exploring the progenitors of brightest cluster galaxies at z ∼ 2. Monthly Notices of the Royal Astronomical Society, 464 (2). pp. 1393-1414. ISSN 1365-2966

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Abstract

We present a new method for tracing the evolution of brightest cluster galaxies (BCGs) from z ∼ 2 to z ∼ 0. We conclude on the basis of semi-analytical models that the best method to select BCG progenitors at z ∼ 2 is a hybrid environmental density and stellar mass ranking approach. Ultimately, we are able to retrieve 45 per cent of BCG progenitors. We apply this method on the Cosmic Assembly Near-infrared Deep Extragalactic Legacy Survey, Ultra Deep Survey data to construct a progenitor sample at high redshift. We furthermore populate the comparisons in local Universe by using Sloan Digital Sky Survey data with statistically likely contamination to ensure a fair comparison between high and low redshifts. Using these samples we demonstrate that the BCG sizes have grown by a factor of ∼3.2 since z ∼ 2, and BCG progenitors are mainly late-type galaxies, exhibiting less concentrated profiles than their early type local counterparts. We find that BCG progenitors have more disturbed morphologies. In contrast, local BCGs have much smoother profiles. Moreover, we find that the stellar masses of BCGs have grown by a factor of ∼2.5 since z ∼ 2, and the star formation rate of BCG progenitors has a median value of 13.5 Mʘ yr‾¹, much higher than their quiescent local descendants. We demonstrate that over z = 1–2 star formation and merging contribute equally to BCG mass growth. However, merging plays a dominant role in BCG assembly at z ≲ 1. We also find that BCG progenitors at high z are not significantly different from other galaxies of similar mass at the same epoch. This suggests that the processes which differentiate BCGs from normal massive elliptical galaxies must occur at z ≲ 2.

Item Type: Article
Additional Information: This article has been published in Monthly Notices of the Royal Astronomical Society ©2016 The Authors. Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved.
Keywords: Galaxies: clusters: general; Galaxies: evolution; Galaxies: formation
Schools/Departments: University of Nottingham, UK > Faculty of Science > School of Physics and Astronomy
Identification Number: 10.1093/mnras/stw2406
Depositing User: Aragon-salamanca, Alfonso
Date Deposited: 09 Jan 2017 15:01
Last Modified: 13 Oct 2017 08:07
URI: http://eprints.nottingham.ac.uk/id/eprint/39707

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