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ID 47045
file
creator
Haines, C. P.
Pereira, M. J.
Smith, G. P.
Egami, E.
Babul, A.
Finoguenov, A.
Ziparo, F.
McGee, S. L.
Rawle, T. D.
Moran, S. M.
subject
galaxies: active – galaxies: clusters: general – galaxies: evolution – galaxies: stellar content
NDC
Astronomy. Space sciences
abstract
We present a study of the spatial distribution and kinematics of star-forming galaxies in 30 massive clusters at 0.15 < z < 0.30, combining wide-field Spitzer 24 μm and GALEX near-ultraviolet imaging with highly complete spectroscopy of cluster members. The fraction (fSF) of star-forming cluster galaxies rises steadily with clustercentric radius, increasing fivefold by 2r_200, but remains well below field values even at 3r_200. This suppression of star formation at large radii cannot be reproduced by models in which star formation is quenched in infalling field galaxies only once they pass within r_200 of the cluster, but is consistent with some of them being first pre-processed within galaxy groups. Despite the increasing fSF-radius trend, the surface density of star-forming galaxies actually declines steadily with radius, falling ∼15× from the core to 2r_200. This requires star formation to survive within recently accreted spirals for 2–3 Gyr to build up the apparent over-density of star-forming galaxies within clusters. The velocity dispersion profile of the star-forming galaxy population shows a sharp peak of 1.44 σ_ν at 0.3r_500, and is 10%–35% higher than that of the inactive cluster members at all cluster-centric radii, while their velocity distribution shows a flat, top-hat profile within r_500. All of these results are consistent with star-forming cluster galaxies being an infalling population, but one that must also survive ∼0.5–2 Gyr beyond passing within r_200. By comparing the observed distribution of star-forming galaxies in the stacked caustic diagram with predictions from the Millennium simulation, we obtain a best-fit model in which star formation rates decline exponentially on quenching timescales of 1.73 ± 0.25 Gyr upon accretion into the cluster.
description
C.P.H. was funded by CONICYT Anillo project ACT-1122. G.P.S. acknowledges support from the Royal Society. F.Z. and G.P.S. acknowledge support from the Science and Technology Facilities Council. We acknowledge NASA funding for this project under the Spitzer program GO:40872. This work was supported in part by the National Science Foundation under grant No. AST-1211349. The Millennium simulation databases used in this paper and the web application providing online access to them were constructed as part of the activities of the German Astrophysical Virtual Observatory.
journal title
The Astrophysical Journal
volume
Volume 806
issue
Issue 1
start page
101
date of issued
2015-06-10
publisher
IOP Publishing
issn
0004-637X
1538-4357
ncid
publisher doi
language
eng
nii type
Journal Article
HU type
Journal Articles
DCMI type
text
format
application/pdf
text version
publisher
rights
© 2015. The American Astronomical Society. All rights reserved.
relation url
department
Graduate School of Science