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Main Authors: Beattie, James R., Kolborg, Anne Noer, Ramirez-Ruiz, Enrico, Federrath, Christoph
Format: Preprint
Published: 2025
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Online Access:https://arxiv.org/abs/2501.09855
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author Beattie, James R.
Kolborg, Anne Noer
Ramirez-Ruiz, Enrico
Federrath, Christoph
author_facet Beattie, James R.
Kolborg, Anne Noer
Ramirez-Ruiz, Enrico
Federrath, Christoph
contents The interstellar medium (ISM) of disk galaxies is turbulent, and yet the fundamental nature of ISM turbulence, the energy cascade, is not understood in detail. In this study, we use high-resolution simulations of a hydrodynamical, gravitationally stratified, supernova (SNe)-driven, multiphase ISM to probe the nature of a galactic turbulence cascade. Through the use of velocity flux transfer functions split into interactions between compressible $\mathbf{u}_c$ and incompressible $\mathbf{u}_s$ modes, we show that there exists a large-to-small-scale cascade in both $\mathbf{u}_c$ and $\mathbf{u}_s$ when mediated by an additional $\mathbf{u}_s$ mode. But the $\mathbf{u}_s$ cascade is highly non-local. Moreover, there is a $\mathbf{u}_c$ mediated component of the $\mathbf{u}_s$ cascade that proceeds in the opposite direction -- an inverse cascade from small-to-large scales. The cascade feeds flux into scales well beyond the scale height, energizing the winds and fueling the direct cascades. Both the strongly non-local and the inverse $\mathbf{u}_s$ cascades happen on scales that have a power law $\mathbf{u}_s$ energy spectrum, highlighting how degenerate the spectrum is to the true underlying physical processes. We directly show that the inverse cascade comes from $\mathbf{u}_s$ modes interacting with expanding SNe remnants (SNRs) and that $\mathbf{u}_s$ modes are generated to leading order via baroclinic, highly corrugated cooling layers between warm $(T\lesssim 10^4\,\rm{K})$ and hot $(T\gg10^4\,\rm{K})$ gas in these SNRs. Finally, we outline a complete phenomenology for SNe-driven turbulence in a galactic disk, estimate a $10^{-16}\,\rm{G}$ Biermann field generated from SNR cooling layers, and highlight the strong deviations that SNe-driven turbulence has from the conventional Kolmogorov model.
format Preprint
id arxiv_https___arxiv_org_abs_2501_09855
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle So long Kolmogorov: the forward and backward turbulence cascades in a supernovae-driven, multiphase interstellar medium
Beattie, James R.
Kolborg, Anne Noer
Ramirez-Ruiz, Enrico
Federrath, Christoph
Astrophysics of Galaxies
High Energy Astrophysical Phenomena
The interstellar medium (ISM) of disk galaxies is turbulent, and yet the fundamental nature of ISM turbulence, the energy cascade, is not understood in detail. In this study, we use high-resolution simulations of a hydrodynamical, gravitationally stratified, supernova (SNe)-driven, multiphase ISM to probe the nature of a galactic turbulence cascade. Through the use of velocity flux transfer functions split into interactions between compressible $\mathbf{u}_c$ and incompressible $\mathbf{u}_s$ modes, we show that there exists a large-to-small-scale cascade in both $\mathbf{u}_c$ and $\mathbf{u}_s$ when mediated by an additional $\mathbf{u}_s$ mode. But the $\mathbf{u}_s$ cascade is highly non-local. Moreover, there is a $\mathbf{u}_c$ mediated component of the $\mathbf{u}_s$ cascade that proceeds in the opposite direction -- an inverse cascade from small-to-large scales. The cascade feeds flux into scales well beyond the scale height, energizing the winds and fueling the direct cascades. Both the strongly non-local and the inverse $\mathbf{u}_s$ cascades happen on scales that have a power law $\mathbf{u}_s$ energy spectrum, highlighting how degenerate the spectrum is to the true underlying physical processes. We directly show that the inverse cascade comes from $\mathbf{u}_s$ modes interacting with expanding SNe remnants (SNRs) and that $\mathbf{u}_s$ modes are generated to leading order via baroclinic, highly corrugated cooling layers between warm $(T\lesssim 10^4\,\rm{K})$ and hot $(T\gg10^4\,\rm{K})$ gas in these SNRs. Finally, we outline a complete phenomenology for SNe-driven turbulence in a galactic disk, estimate a $10^{-16}\,\rm{G}$ Biermann field generated from SNR cooling layers, and highlight the strong deviations that SNe-driven turbulence has from the conventional Kolmogorov model.
title So long Kolmogorov: the forward and backward turbulence cascades in a supernovae-driven, multiphase interstellar medium
topic Astrophysics of Galaxies
High Energy Astrophysical Phenomena
url https://arxiv.org/abs/2501.09855