pycbc_optimize_snr: Implement mass dependent bounds on spin parameters (

#4176)

* Applying spin bounds based upon object mass~

* Updated reference to correct paper

* Adding spin bounds based on upper bounds of masses

* removing unnecessary additions

* Changing max mass2 to the right quantities

* Creating maxeta + reusing maxm1

* minor cleanup

* fixed min / max eta values

* fixed min / max eta

* Correcting maxm2 equation

* more readable/less redundant comment

---------

Co-authored-by: Thomas Dent <[email protected]>

bin/pycbc_optimize_snr

@@ -33,6 +33,10 @@ MIN_CPT_MASS = 0.99
 # Set a large maximum total mass
 MAX_MTOTAL = 500.
 
+# Set a notional maximum and minimum possible eta
+MAX_ETA = 0.24999999999
+MIN_ETA = 0.01
+
 Nfeval = 0
 start_time = time.time()
 
@@ -351,14 +355,24 @@ assert maxchirp < 250.
 # Establish minimum eta: find the most asymmetric mass point
 # nb function name is 'mass2' but it doesn't enforce m2 < m1!
 maxm1 = cv._mass2_from_mchirp_mass1(maxchirp, MIN_CPT_MASS)
-mineta = max(cv.eta_from_mass1_mass2(maxm1, MIN_CPT_MASS), 0.01)
+mineta = max(cv.eta_from_mass1_mass2(maxm1, MIN_CPT_MASS), MIN_ETA)
+
+# Use max chirp and max eta to find the upper bound on mass2
+maxm2 = cv.mass2_from_mchirp_eta(maxchirp, MAX_ETA)
+
+# Astrophysical spin bounds dependent on system masses - https://inspirehep.net/literature/1124003
+# If masses can be > 3 then allow them BH spin range
+minspin1z = -0.4 if maxm1 < 3 else -0.9
+maxspin1z = 0.4 if maxm1 < 3 else 0.9
+minspin2z = -0.4 if maxm2 < 3 else -0.9
+maxspin2z = 0.4 if maxm2 < 3 else 0.9
 
-# Boundaries of the optimization space: dict of (min, max) tuples
+# Boundary of the optimization space
 bounds = {
     'mchirp': (minchirp, maxchirp),
-    'eta': (mineta, 0.24999999999),
-    'spin1z': (-0.9, 0.9),
-    'spin2z': (-0.9, 0.9)
+    'eta': (mineta, MAX_ETA),
+    'spin1z': (minspin1z, maxspin1z),
+    'spin2z': (minspin2z, maxspin2z)
 }
 
 with scheme_context: