From d680f1714673e93f330b2c6f0d2be5fb87d340ff Mon Sep 17 00:00:00 2001
From: Aaron LI <aly@aaronly.me>
Date: Thu, 19 Oct 2017 21:09:21 +0800
Subject: clusters/helper: Add kT_virial() to calculate the virial temperature

---
 fg21sim/extragalactic/clusters/helper.py | 36 ++++++++++++++++++++++++++++++++
 1 file changed, 36 insertions(+)

(limited to 'fg21sim/extragalactic')

diff --git a/fg21sim/extragalactic/clusters/helper.py b/fg21sim/extragalactic/clusters/helper.py
index 6b835a0..20ad9d9 100644
--- a/fg21sim/extragalactic/clusters/helper.py
+++ b/fg21sim/extragalactic/clusters/helper.py
@@ -22,6 +22,10 @@ References
    Cassano et al. 2012, A&A, 548, A100
    http://adsabs.harvard.edu/abs/2012A%26A...548A.100C
 
+.. [fujita2003]
+   Fujita et al. 2003, ApJ, 584, 190;
+   http://adsabs.harvard.edu/abs/2003ApJ...584..190F
+
 .. [murgia2009]
    Murgia et al. 2009, A&A, 499, 679
    http://adsabs.harvard.edu/abs/2009A%26A...499..679M
@@ -103,6 +107,38 @@ def radius_halo(M_main, M_sub, z=0.0):
     return R_halo
 
 
+def kT_virial(mass, z=0.0, radius=None):
+    """
+    Calculate the virial temperature of a cluster.
+
+    Parameters
+    ----------
+    mass : float
+        The virial mass of the cluster.
+        Unit: [Msun]
+    z : float, optional
+        The redshift of the cluster.
+    radius : float, optional
+        The virial radius of the cluster.
+        If no provided, then invoke the above ``radius_virial()``
+        function to calculate it.
+        Unit: [kpc]
+
+    Returns
+    -------
+    kT : float
+       The virial temperature of the cluster.
+       Unit: [keV]
+
+    Reference: Ref.[fujita2003],Eq.(48)
+    """
+    if radius is None:
+        radius = radius_virial(mass=mass, z=z)  # [kpc]
+    kT = AC.mu*AC.u * AC.G * mass*AUC.Msun2g / (2*radius*AUC.kpc2cm)  # [erg]
+    kT *= AUC.erg2keV  # [keV]
+    return kT
+
+
 def mass_to_kT(mass, z=0.0):
     """
     Calculate the cluster ICM temperature from its mass using the
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