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Jellyfish: The origin and distribution of extreme ram-pressure stripping events in massive galaxy clusters

McPartland, Conor; Ebeling, Harald; Roediger, Elke; Blumenthal, Kelly

Authors

Conor McPartland

Harald Ebeling

Dr Elke Roediger E.Roediger@hull.ac.uk
Senior Lecturer/ Director of Studies for Physics

Kelly Blumenthal

Abstract

We investigate the observational signatures and physical origin of ram-pressure stripping (RPS) in 63 massive galaxy clusters at z = 0.3–0.7, based on images obtained with the Hubble Space Telescope. Using a training set of a dozen ‘jellyfish’ galaxies identified earlier in the same imaging data, we define morphological criteria to select 211 additional, less obvious cases of RPS. Spectroscopic follow-up observations of 124 candidates so far confirmed 53 as cluster members. For the brightest and most favourably aligned systems, we visually derive estimates of the projected direction of motion based on the orientation of apparent compression shocks and debris trails. Our findings suggest that the onset of these events occurs primarily at large distances from the cluster core (>400 kpc), and that the trajectories of the affected galaxies feature high-impact parameters. Simple models show that such trajectories are highly improbable for galaxy infall along filaments but common for infall at high velocities, even after observational biases are accounted for, provided the duration of the resulting RPS events is ≲500 Myr. We thus tentatively conclude that extreme RPS events are preferentially triggered by cluster mergers, an interpretation that is supported by the disturbed dynamical state of many of the host clusters. This hypothesis implies that extreme RPS might occur also near the cores of merging poor clusters or even merging groups of galaxies. Finally, we present nine additional ‘jellyfish” galaxies at z > 0.3 discovered by us, thereby doubling the number of such systems known at intermediate redshift.

Publication Date Jan 21, 2016
Journal Monthly notices of the Royal Astronomical Society
Print ISSN 0035-8711
Electronic ISSN 1365-2966
Publisher Oxford University Press (OUP)
Peer Reviewed Peer Reviewed
Volume 455
Issue 3
Pages 2994-3008
Institution Citation McPartland, C., Ebeling, H., Roediger, E., & Blumenthal, K. (2016). Jellyfish: The origin and distribution of extreme ram-pressure stripping events in massive galaxy clusters. Monthly notices, containing papers, abstracts of papers, and reports of the proceedings of the Society, 455(3), 2994-3008. https://doi.org/10.1093/mnras/stv2508
DOI https://doi.org/10.1093/mnras/stv2508
Keywords Galaxies -- clusters -- intracluster medium; Galaxies -- evolution, Galaxies -- structure
Publisher URL http://mnras.oxfordjournals.org/content/455/3/2994.abstract?sid=d3a3a0d2-361a-4d36-b781-d17a9c6e55ae
Copyright Statement © 2016 The Authors. Published by Oxford University Press on behalf of the Royal Astronomical Society
Additional Information This article has been accepted for publication 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.

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Copyright Statement
© 2016 The Authors. Published by Oxford University Press on behalf of the Royal Astronomical Society



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