Instability of Supersonic Cold Streams Feeding Galaxies II. Nonlinear Evolution of Surface and Body Modes of Kelvin-Helmholtz Instability
| Autor: | Mark R. Krumholz, Nir Mandelker, Avishai Dekel, Dan Padnos, Elad Steinberg, Yuval Birnboim |
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| Rok vydání: | 2018 |
| Předmět: |
Physics
Radiative cooling FOS: Physical sciences Astronomy and Astrophysics Astrophysics Radius Astrophysics::Cosmology and Extragalactic Astrophysics Astrophysics - Astrophysics of Galaxies 01 natural sciences Instability Galaxy Virial theorem Redshift 010305 fluids & plasmas 13. Climate action Space and Planetary Science Astrophysics of Galaxies (astro-ph.GA) 0103 physical sciences Halo Density contrast 010303 astronomy & astrophysics |
| DOI: | 10.48550/arxiv.1803.09105 |
| Popis: | As part of our long-term campaign to understand how cold streams feed massive galaxies at high redshift, we study the Kelvin-Helmholtz instability (KHI) of a supersonic, cold, dense gas stream as it penetrates through a hot, dilute circumgalactic medium (CGM). A linear analysis (Paper I) showed that, for realistic conditions, KHI may produce nonlinear perturbations to the stream during infall. Therefore, we proceed here to study the nonlinear stage of KHI, still limited to a two-dimensional slab with no radiative cooling or gravity. Using analytic models and numerical simulations, we examine stream breakup, deceleration and heating via surface modes and body modes. The relevant parameters are the density contrast between stream and CGM ($\delta$), the Mach number of the stream velocity with respect to the CGM ($M_{\rm b}$) and the stream radius relative to the halo virial radius ($R_{\rm s}/R_{\rm v}$). We find that sufficiently thin streams disintegrate prior to reaching the central galaxy. The condition for breakup ranges from $R_{\rm s} < 0.03 R_{\rm v}$ for $(M_{\rm b} \sim 0.75, \delta \sim 10)$ to $R_{\rm s} < 0.003 R_{\rm v}$ for $(M_{\rm b} \sim 2.25, \delta \sim 100)$. However, due to the large stream inertia, KHI has only a small effect on the stream inflow rate and a small contribution to heating and subsequent Lyman-$\alpha$ cooling emission. Comment: The main astrophysical results are Figure 22 and Figure 23. Final 7 pages are appendices. Accepted to MNRAS |
| Databáze: | OpenAIRE |
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