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تسجيل مستخدم جديدVelocity structure functions in multiphase turbulence: interpreting kinematics of H$alpha$ filaments in cool core clusters
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The central regions of cool-core galaxy clusters harbour multiphase gas with temperatures ranging from $10 mathrm{K}$--$10^7 mathrm{K}$. Feedback from AGN jets prevents the gas from undergoing a catastrophic cooling flow. However, the exact mechanism of this feedback energy input is unknown, mainly due to the lack of velocity measurements of the hot phase gas, which has large thermal velocities. However, recent observations have measured the velocity structure functions ($mathrm{VSF}$s) of the cooler phases (at $10 mathrm{K}$ and $10^4 mathrm{K}$) and used them to indirectly estimate the motions of the hot phase. In the first part of this study, we conduct high-resolution ($384^3$--$1536^3$ resolution elements) simulations of homogeneous isotropic subsonic turbulence, without radiative cooling. We analyse the second-order velocity structure functions ($mathrm{VSF}_2$) in these simulations and study the effects of varying spatial resolution, the introduction of magnetic fields and the effect of line of sight (LOS) projection on the $mathrm{VSF}_2$. In the second part of the study, we analyse high-resolution ($768^3$ resolution elements) idealised simulations of multiphase turbulence in the intracluster medium (ICM) from Mohapatra et al 2021. We compare $mathrm{VSF}_2$ for both the hot ($Tsim10^7 mathrm{K}$) and cold ($Tsim10^4 mathrm{K}$) phases. We also look for the effect of LOS projection. For turbulence without radiative cooling, we observe a steepening in the slopes of the $mathrm{VSF}_2$ upon projection. In our runs with radiative cooling and multiphase gas, we find that the $mathrm{VSF}_2$ of the hot and cold phases have similar scaling, but introducing magnetic fields steepens the $mathrm{VSF}_2$ of the cold phase only. We also find that projection along the LOS steepens the $mathrm{VSF}_2$ for the hot phase and mostly flattens it for the cold phase.
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