The Impact of Type Ia Supernovae in Quiescent Galaxies. II. Energetics and Turbulence

Miao Li, Yuan Li, Greg L. Bryan, Eve C. Ostriker, Eliot Quataert

Research output: Contribution to journalArticle

Abstract

Type Ia supernovae (SNe Ia) provide unique and important feedback in quiescent galaxies, but their impact has been underappreciated. In this paper, we analyze a series of high-resolution simulations to examine the energetics and turbulence of the medium under SNe Ia. We find that when SN remnants are resolved, their effects differ distinctly from a volumetric heating term, as is commonly assumed in unresolved simulations. First, the net heating is significantly higher than expected, by 30 ± 10% per cooling time. This is because a large fraction of the medium is pushed into lower densities, which cool inefficiently. Second, the medium is turbulent; the root-mean-squared (rms) velocity of the gas to 20-50 km s-1 on a driving scale of tens of parsecs. The velocity field of the medium is dominated by compressional modes, which are larger than the solenoidal components by a factor of 3-7. Third, the hot gas has a very broad density distribution. The ratio between the density fluctuations and the rms Mach number, parameterized as b, is 2-20. This is in contrast to previous simulations of turbulent media, which have found b ≲ 1. The difference is mainly caused by the localized heating of SNe Ia, which creates a large density contrast. Last, the typical length scale of a density fluctuation grows with time, forming increasingly larger bubbles and filamentary ridges. These underlying density fluctuations need to be included when X-ray observations are interpreted.

Original languageEnglish (US)
Article number23
JournalAstrophysical Journal
Volume898
Issue number1
DOIs
StatePublished - Jul 20 2020

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science

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