University of Hertfordshire

From the same journal

From the same journal

Isolating signatures of major cloud-cloud collisions - II. The lifetimes of broad bridge features

Research output: Contribution to journalArticlepeer-review


  • T.~J. Haworth
  • K. Shima
  • E.~J. Tasker
  • Y. Fukui
  • K. Torii
  • K. Takahira
  • A. Habe
  • James Dale
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Original languageEnglish
Pages (from-to)1634-1643
Number of pages10
JournalMonthly Notices of the Royal Astronomical Society
Early online date6 Oct 2015
Publication statusPublished - 1 Dec 2015


We investigate the longevity of broad bridge features in position–velocity diagrams that appear as a result of cloud–cloud collisions. Broad bridges will have a finite lifetime due to the action of feedback, conversion of gas into stars and the time-scale of the collision. We make a series of analytic arguments with which to estimate these lifetimes. Our simple analytic arguments suggest that for collisions between clouds larger than R ∼ 10 pc the lifetime of the broad bridge is more likely to be determined by the lifetime of the collision rather than the radiative or wind feedback disruption time-scale. However, for smaller clouds feedback becomes much more effective. This is because the radiative feedback time-scale scales with the ionizing flux Nly as

so a reduction in cloud size requires a relatively large decrease in ionizing photons to maintain a given time-scale. We find that our analytic arguments are consistent with new synthetic observations of numerical simulations of cloud–cloud collisions (including star formation and radiative feedback). We also argue that if the number of observable broad bridges remains ∼ constant, then the disruption time-scale must be roughly equivalent to the collision rate. If this is the case, our analytic arguments also provide collision rate estimates, which we find are readily consistent with previous theoretical models at the scales they consider (clouds larger than about 10 pc) but are much higher for smaller clouds.


This article has been accepted for publication in Monthly Notices of the Royal Astronomical Society. © 2015 The Authors. Published by Oxford University Press on behalf of the Royal Astronomical Society.

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