clusters/halo: Estimate turbulence acceleration w.r.t. injection scale

The turbulence injection scale ~ halo size

1 files changed, 23 insertions, 0 deletions

diff --git a/fg21sim/extragalactic/clusters/helper.py b/fg21sim/extragalactic/clusters/helper.py
index cac6401..10c4f12 100644
--- a/fg21sim/extragalactic/clusters/helper.py
+++ b/fg21sim/extragalactic/clusters/helper.py
@@ -360,6 +360,29 @@ def time_crossing(M_main, M_sub, z=0.0):
     return time
 
 
+def time_turbulence(M_main, M_sub, z=0.0, configs=CONFIGS):
+    """
+    The timescale that the compressive turbulence persists, which is
+    estimated as:
+        τ_turb ≅ 2*d / v_impact,
+    where d ≅ L ≅ R_vir / 3,
+    and L is also the turbulence injection scale.
+    During this timescale, the merger-induced turbulence is regarded
+    to accelerate the relativistic electrons effectively.
+
+    Unit: [Gyr]
+    """
+    # Turbulence injection scale factor
+    key = "extragalactic/halos/f_lturb"
+    f_lturb = configs.getn(key)
+    R_vir = radius_virial(M_main, z)  # [kpc]
+    distance = 2*R_vir * f_lturb
+    vi = velocity_impact(M_main, M_sub, z)  # [km/s]
+    uconv = AUC.kpc2km * AUC.s2Gyr  # [s kpc/km] => [Gyr]
+    time = uconv * distance / vi  # [Gyr]
+    return time
+
+
 def draw_halo(radius, nr=2.0, felong=None, rotation=None):
     """
     Draw the template image of one halo, which is used to simulate