Shock Waves and Energy Dissipation in Magnetohydrodynamic Turbulence. (arXiv:1811.03207v1 [astro-ph.HE])
<a href="http://arxiv.org/find/astro-ph/1/au:+Park_J/0/1/0/all/0/1">Junseong Park</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Ryu_D/0/1/0/all/0/1">Dongsu Ryu</a> (UNIST, Korea)
Shock waves play an important role in turbulent astrophysical media by
compressing the gas and dissipating the turbulent energy into the thermal
energy. We here study shocks in magnetohydrodynamic turbulence using
high-resolution simulations. Turbulent Mach numbers of
$mathcal{M}_text{turb}=0.5-7$ and initial magnetic fields of plasma beta
$beta_0=0.1 – 10$ are considered, targeting turbulences in interstellar and
intracluster media. Specifically, we present the statistics of fast and slow
shocks, such as the distribution of shock Mach numbers ($M_s$) and the energy
dissipation at shocks, based on refined methodologies for their
quantifications. While most shocks form with low $M_s$, strong shocks follow
exponentially decreasing distributions of $M_s$. More shocks appear for larger
$mathcal{M}_text{turb}$ and larger $beta_0$. Fast shock populations dominate
over slow shocks if $beta_0gg1$, but substantial populations of slow shocks
develop in the cases of $betalesssim1$, i.e., strong background fields. The
shock dissipation of turbulent energy occurs preferentially at fast shocks with
$M_slesssim$ a few to several, and the dissipation at strong shocks shows
exponentially decreasing functions of $M_s$. The energy dissipation at shocks,
normalized to the energy injection,
$epsilon_text{shock}/epsilon_text{inj}$, is estimated to be in the range of
$sim0.1-0.5$, except for the case of $mathcal{M}_text{turb}=0.5$ and
$beta_0=0.1$ where the shock dissipation is negligible. The fraction decreases
with $mathcal{M}_text{turb}$; it is close to $sim0.4-0.6$ for
$mathcal{M}_text{turb}=0.5$, while it is $sim0.1-0.25$ for
$mathcal{M}_text{turb}=7$. The rest of the turbulent energy is expected to
dissipate through the turbulent cascade. Our work will add insights into the
interpretations of physical processes in turbulent interstellar and
intracluster media.
Shock waves play an important role in turbulent astrophysical media by
compressing the gas and dissipating the turbulent energy into the thermal
energy. We here study shocks in magnetohydrodynamic turbulence using
high-resolution simulations. Turbulent Mach numbers of
$mathcal{M}_text{turb}=0.5-7$ and initial magnetic fields of plasma beta
$beta_0=0.1 – 10$ are considered, targeting turbulences in interstellar and
intracluster media. Specifically, we present the statistics of fast and slow
shocks, such as the distribution of shock Mach numbers ($M_s$) and the energy
dissipation at shocks, based on refined methodologies for their
quantifications. While most shocks form with low $M_s$, strong shocks follow
exponentially decreasing distributions of $M_s$. More shocks appear for larger
$mathcal{M}_text{turb}$ and larger $beta_0$. Fast shock populations dominate
over slow shocks if $beta_0gg1$, but substantial populations of slow shocks
develop in the cases of $betalesssim1$, i.e., strong background fields. The
shock dissipation of turbulent energy occurs preferentially at fast shocks with
$M_slesssim$ a few to several, and the dissipation at strong shocks shows
exponentially decreasing functions of $M_s$. The energy dissipation at shocks,
normalized to the energy injection,
$epsilon_text{shock}/epsilon_text{inj}$, is estimated to be in the range of
$sim0.1-0.5$, except for the case of $mathcal{M}_text{turb}=0.5$ and
$beta_0=0.1$ where the shock dissipation is negligible. The fraction decreases
with $mathcal{M}_text{turb}$; it is close to $sim0.4-0.6$ for
$mathcal{M}_text{turb}=0.5$, while it is $sim0.1-0.25$ for
$mathcal{M}_text{turb}=7$. The rest of the turbulent energy is expected to
dissipate through the turbulent cascade. Our work will add insights into the
interpretations of physical processes in turbulent interstellar and
intracluster media.
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