clusters/halo: Add option "kT_out" to tune cluster temperature

3 files changed, 16 insertions, 5 deletions

diff --git a/fg21sim/configs/20-extragalactic.conf.spec b/fg21sim/configs/20-extragalactic.conf.spec
index 82c6d45..ea6479f 100644
--- a/fg21sim/configs/20-extragalactic.conf.spec
+++ b/fg21sim/configs/20-extragalactic.conf.spec
@@ -124,6 +124,15 @@
   # field strength within the ICM and is also assumed to be uniform.
   eta_b = float(default=0.001, min=1e-5, max=0.1)
 
+  # The temperature of the outer gas surrounding the cluster.  Accretion
+  # shocks form near the cluster virial radius during the cluster formation,
+  # which can heat the cluster ICM to have a higher temperature than the
+  # virial temperature:
+  #     kT_icm ~ kT_vir + 1.5 * kT_out
+  # Reference: Fujita et al. 2003, ApJ, 584, 190; Eq.(49)
+  # Unit: [keV]
+  kT_out = float(default=0.5, min=0, max=1)
+
   # Filename prefix for this component
   prefix = string(default="cluster")
   # Output directory to save the simulated results
diff --git a/fg21sim/extragalactic/clusters/halo.py b/fg21sim/extragalactic/clusters/halo.py
index d3b5dd1..bf8e643 100644
--- a/fg21sim/extragalactic/clusters/halo.py
+++ b/fg21sim/extragalactic/clusters/halo.py
@@ -327,9 +327,7 @@ class RadioHalo:
         if not hasattr(self, "_tau_acceleration"):
             Mach = self.Mach_turbulence
             Rvir = helper.radius_virial(mass=self.M_main, z=self.z_merger)
-            kT = helper.kT_cluster(mass=self.M_main, z=self.z_merger,
-                                   radius=Rvir)  # [keV]
-            cs = helper.speed_sound(kT)  # [km/s]
+            cs = helper.speed_sound(self.kT_main)  # [km/s]
             # Turbulence injection scale
             L0 = self.f_lturb * Rvir  # [kpc]
             x = cs*AUC.km2cm / AC.c
diff --git a/fg21sim/extragalactic/clusters/helper.py b/fg21sim/extragalactic/clusters/helper.py
index d77c63e..86662e1 100644
--- a/fg21sim/extragalactic/clusters/helper.py
+++ b/fg21sim/extragalactic/clusters/helper.py
@@ -153,7 +153,9 @@ def kT_cluster(mass, z=0.0, radius=None):
     the cluster (near the virial radius) which can heat the gas,
     therefore the ICM has a higher temperature than the virial
     temperature, which can be estimated as:
-        T_icm = T_vir + 1.5*T_1 ~ T_vir + 0.8 [keV]
+        kT_icm ~ kT_vir + 1.5 * kT_out
+    where kT_out the temperature of the outer gas surround the cluster,
+    which may be ~0.5-1.0 keV.
 
     Reference: Ref.[fujita2003],Eq.(49)
 
@@ -163,8 +165,10 @@ def kT_cluster(mass, z=0.0, radius=None):
        The temperature of the cluster ICM.
        Unit: [keV]
     """
+    key = "extragalactic/clusters/kT_out"
+    kT_out = CONFIGS.getn(key)
     kT_vir = kT_virial(mass=mass, z=z, radius=radius)
-    kT_icm = kT_vir + 0.8
+    kT_icm = kT_vir + 1.5*kT_out
     return kT_icm