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Kinematic clues to the origins of starless HI clouds : dark galaxies or tidal debris?

Taylor, R., Davies, Jonathan, Jáchym, P., Keenan, Olivia, Minchin, R. F., Palous, J., Smith, R. and Wünsch, R. 2017. Kinematic clues to the origins of starless HI clouds : dark galaxies or tidal debris? Monthly Notices of the Royal Astronomical Society 467 (3) , pp. 3648-3661. 10.1093/mnras/stx187

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Isolated H i clouds with no optical counterparts are often taken as evidence for galaxy–galaxy interactions, though an alternative hypothesis is that these are primordial ‘dark galaxies’ that have not formed stars. Similarly, certain kinematic features in H i streams are also controversial, sometimes taken as evidence of dark galaxies but also perhaps explicable as the result of harassment. We numerically model the passage of a galaxy through the gravitational field of cluster. The galaxy consists of smoothed particle hydrodynamics particles for the gas and N-bodies for the stars and dark matter, while the cluster includes the gravitational effects of substructure using 400 subhaloes (the effects of the intracluster medium are ignored). We find that harassment can indeed produce long H i streams and these streams can include kinematic features resembling dark galaxy candidates such as VIRGOHI21. We also show that apparent clouds with diameter <20 kpc and velocity widths <50 km s−1 are almost invariably produced in these simulations, making tidal debris a highly probable explanation. In contrast, we show that the frequency of isolated clouds of the same size but velocity width >100 km s−1 is negligible – making this a very unlikely explanation for the observed clouds in the Virgo cluster with these properties.

Item Type: Article
Date Type: Publication
Status: Published
Schools: Physics and Astronomy
Subjects: Q Science > QB Astronomy
Q Science > QC Physics
Uncontrolled Keywords: galaxies: evolution
Additional Information: This article has been accepted for publication in Monthly Notices of the Royal Astronomical Society (2017)Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved.
Publisher: Oxford University Press
ISSN: 0035-8711
Date of First Compliant Deposit: 8 June 2017
Date of Acceptance: 18 January 2017
Last Modified: 05 May 2023 09:19

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