clusters/halo: Fold _merger_idx() into _merger_event()

Update _merger_time() accordingly.

1 files changed, 11 insertions, 18 deletions

diff --git a/fg21sim/extragalactic/clusters/halo.py b/fg21sim/extragalactic/clusters/halo.py
index 14a9028..b11f060 100644
--- a/fg21sim/extragalactic/clusters/halo.py
+++ b/fg21sim/extragalactic/clusters/halo.py
@@ -774,27 +774,12 @@ class RadioHaloAM(RadioHalo1M):
         """
         return self.age_merger[-1]
 
-    def _merger_idx(self, t):
-        """
-        Determine the index of the merger event within which the given
-        time is located, i.e.:
-            age_merger[idx-1] >= t > age_merger[idx]
-        """
-        return (self.age_merger > t).sum()
-
-    def _merger_time(self, t):
-        """
-        Determine the beginning time of the merger event within which
-        the given time is located.
-        """
-        idx = self._merger_idx(t)
-        return self.age_merger[idx]
-
     def _merger_event(self, t):
         """
-        Return the merger event at cosmic time ``t``.
+        Return the most recent merger event happend before the given time,
+        i.e., the merger event that the given time locates in.
         """
-        idx = self._merger_idx(t)
+        idx = (self.age_merger > t).sum()
         return {
             "idx": idx,
             "M_main": self.M_main[idx],
@@ -803,6 +788,14 @@ class RadioHaloAM(RadioHalo1M):
             "age": self.age_merger[idx],
         }
 
+    def _merger_time(self, t):
+        """
+        Determine the beginning time of the merger event within which
+        the given time is located.
+        """
+        merger = self._merger_event(t)
+        return merger["age"]
+
     def mass_merged(self, t):
         """
         The mass of merged cluster at the given (cosmic) time.