From 2ee32e7196f83a9350a2b83c03846f6282d7ffe9 Mon Sep 17 00:00:00 2001 From: Aaron LI Date: Sat, 21 Oct 2017 22:13:42 +0800 Subject: clusters/halo: Rewrite turbulence acceleration & diffusion coefficient! The previous calculation of the turbulence acceleration efficiency has significant problems, which is too low, i.e., the acceleration timescale is too large (~10 Gyr). However, it is reported that turbulent acceleration has a timescale ~100 Myr (0.1 Gyr). I believe this problem is due to the over-simplification to the formula proposed by [cassano2005]. Rewrite the turbulence acceleration and diffusion coefficient calculations, adopting the method proposed by [brunetti2016]. To this end, two new options "f_lturb" and "f_acc" are introduced to tune the results. --- fg21sim/configs/20-extragalactic.conf.spec | 14 ++++++++++++-- 1 file changed, 12 insertions(+), 2 deletions(-) (limited to 'fg21sim/configs') diff --git a/fg21sim/configs/20-extragalactic.conf.spec b/fg21sim/configs/20-extragalactic.conf.spec index 75ea0ec..32311a0 100644 --- a/fg21sim/configs/20-extragalactic.conf.spec +++ b/fg21sim/configs/20-extragalactic.conf.spec @@ -132,8 +132,18 @@ # Giant radio halos for clusters with recent major mergers [[halos]] - # Roughly the fraction of turbulence energy transformed to accelerate - # the electrons, describing the efficiency of turbulence acceleration. + # The turbulence is generally injected at the cluster center during + # a merger. This option parameterize the turbulence injection scale + # to be a fraction of the virial radius of the (main) cluster. + f_lturb = float(default=0.5, min=0.1, max=1.0) + + # The custom option to tune the turbulent acceleration timescale, which + # controls the relativistic particle acceleration efficiencies. + f_acc = float(default=1.5, min=0.1, max=10) + + # The fraction of cluster thermal energy originating from turbulent + # dissipation, which describes the turbulence intensity in the ICM, + # and determines its Mach number. eta_turb = float(default=0.2, min=0.1, max=1.0) # Ratio of the total energy injected into cosmic-ray electrons during -- cgit v1.2.2