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Ultraviolet tails and trails in cluster galaxies: A sample of candidate gaseous stripping events in Coma

Smith, RJ and Lucey, JR and Hammer, D and Hornschemeier, AE and Carter, D and Hudson, MJ and Marzke, RO and Mouhcine, M and Eftekharzadeh, S and James, PA and Khosroshahi, H and Kourkchi, E and Karick, A (2010) Ultraviolet tails and trails in cluster galaxies: A sample of candidate gaseous stripping events in Coma. Monthly Notices of the Royal Astronomical Society, 408 (3). pp. 1417-1432. ISSN 0035-8711

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Abstract

We have used new deep observations of the Coma cluster from GALEX to identify 13 star-forming galaxies with asymmetric morphologies in the ultraviolet. Aided by optical broad-band and H-alpha imaging, we interpret the asymmetric features as being due to star formation within gas stripped from the galaxies by interaction with the cluster environment. The selected objects display a range of structures from broad fan-shaped systems of filaments and knots (`jellyfish') to narrower and smoother tails extending up to 100 kpc in length. Some of the features have been discussed previously in the literature, while others are newly identified here. As an ensemble, the candidate stripping events are located closer to the cluster centre than other star-forming galaxies; their radial distribution is similar to that of all cluster members, dominated by passive galaxies. The fraction of blue galaxies which are undergoing stripping falls from 40% in the central 500 kpc, to less than 5% beyond 1 Mpc. We find that tails pointing away from (i.e. galaxies moving towards) the cluster centre are strongly favoured (11/13 cases). From the small number of `outgoing' galaxies with stripping signatures we conclude that the stripping events occur primarily on first passage towards the cluster centre, and are short-lived compared to the cluster crossing time. Using infall trajectories from simulations, the observed fraction of blue galaxies undergoing stripping can be reproduced if the events are triggered at a threshold radius of ~1 Mpc and detectable for ~500 Myr. HST images are available for two galaxies from our sample and reveal compact blue knots coincident with UV and H-alpha emission, apparently forming stars within the stripped material. Our results confirm that stripping of gas from infalling galaxies, and associated star formation in the stripped material, is a widespread phenomenon in rich clusters.

Item Type: Article
Additional Information: This article has been accepted for publication in Monthly Notices of the Royal Astronomical Society ©: 2010 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved.
Uncontrolled Keywords: astro-ph.CO; astro-ph.CO
Subjects: Q Science > QB Astronomy
Q Science > QC Physics
Divisions: Astrophysics Research Institute
Publisher: Oxford University Press
Related URLs:
Date Deposited: 14 Nov 2016 10:35
Last Modified: 14 Nov 2016 10:35
DOI or Identification number: 10.1111/j.1365-2966.2010.17253.x
URI: http://researchonline.ljmu.ac.uk/id/eprint/4800

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