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The cosmic assembly of stellar haloes in massive Early-Type Galaxies

Buitrago, Fernando; Trujillo, Ignacio; Curtis-Lake, Emma; Montes, Mireia; Cooper, Andrew P.; Bruce, Victoria A.; Pérez-González, Pablo G.; Cirasuolo, Michele

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Fernando Buitrago

Ignacio Trujillo

Emma Curtis-Lake

Mireia Montes

Andrew P. Cooper

Victoria A. Bruce

Pablo G. Pérez-González

Michele Cirasuolo


Using the exquisite depth of the Hubble Ultra Deep Field (HUDF12 programme) data set, we explore the ongoing assembly of the outermost regions of the most massive galaxies (Mstellar ≥ 5× 1010 M⊙) at z ≤ 1. The outskirts of massive objects, particularly early-type Galaxies (ETGs), are expected to suffer a dramatic transformation across cosmic time due to continuous accretion of small galaxies. HUDF imaging allows us to study this process at intermediate redshifts in six massive galaxies, exploring the individual surface brightness profiles out to ∼25 effective radii. We find that 5–20 per cent of the total stellar mass for the galaxies in our sample is contained within 10 < R < 50 kpc. These values are in close agreement with numerical simulations, and higher than those reported for local late-type galaxies (≲5 per cent). The fraction of stellar mass stored in the outer envelopes/haloes of massive ETGs increases with decreasing redshift, being 28.7 per cent at  = 0.1, 15.1 per cent at  = 0.65 and 3.5 per cent at  = 2. The fraction of mass in diffuse features linked with ongoing minor merger events is >1–2 per cent, very similar to predictions based on observed close pair counts. Therefore, the results for our small albeit meaningful sample suggest that the size and mass growth of the most massive galaxies have been solely driven by minor and major merging from z = 1 to today.


Buitrago, F., Trujillo, I., Curtis-Lake, E., Montes, M., Cooper, A. P., Bruce, V. A., …Cirasuolo, M. (2017). The cosmic assembly of stellar haloes in massive Early-Type Galaxies. Monthly Notices of the Royal Astronomical Society, 466(4), 4888-4903.

Journal Article Type Article
Acceptance Date Dec 30, 2016
Online Publication Date Jan 9, 2017
Publication Date May 1, 2017
Deposit Date Aug 24, 2017
Publicly Available Date Aug 24, 2017
Journal Monthly Notices of the Royal Astronomical Society
Print ISSN 0035-8711
Electronic ISSN 1365-2966
Publisher Royal Astronomical Society
Peer Reviewed Peer Reviewed
Volume 466
Issue 4
Pages 4888-4903


Published Journal Article (5.7 Mb)

Copyright Statement
This article has been accepted for publication in Monthly notices of the Royal Astronomical Society ©: 2017 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved.

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