Constraints on galactic wind models

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Observational implications are derived for two standard models of supernovae-driven galactic winds: a freely expanding steady-state wind and a wind sourced by a self-similarly expanding superbubble including thermal heat conduction. It is shown that, for the steady-state wind, matching the measured correlation between the soft x-ray luminosity and star formation rate of starburst galaxies is equivalent to producing a scaled wind mass-loading factor relative to the star-formation rate of 0.5–3, in agreement with the amount inferred from metal absorption line measurements. The match requires the asymptotic wind velocity v to scale with the star formation rate M˙∗M˙∗ (in M yr−1) approximately as v∞≃(700−1000)kms−1M˙∗1/6v∞≃(700−1000)kms−1M˙∗1/6. The implied mass injection rate is close to the amount naturally provided by thermal evaporation from the wall of a superbubble in a galactic disc, suggesting thermal evaporation may be a major source of mass-loading. The predicted mass-loading factors from thermal evaporation within the galactic disc alone, however, are somewhat smaller, 0.2–2, so that a further contribution from cloud ablation or evaporation within the wind may be required. Both models may account for the 1.4 GHz luminosity of unresolved radio sources within starburst galaxies for plausible parameters describing the distribution of relativistic electrons. Further observational tests to distinguish the models are suggested.
Original languageEnglish
Number of pages16
JournalMonthly Notices of the Royal Astronomical Society
Early online date17 Jun 2016
Publication statusPublished - 17 Jun 2016


  • galaxies: starburst
  • galaxies: star formation
  • X-rays: galaxies
  • X-rays:
  • radio continuum: galaxies
  • radio continuum: ISM


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