diff options
Diffstat (limited to 'fg21sim/extragalactic')
| -rw-r--r-- | fg21sim/extragalactic/clusters/halo.py | 26 | ||||
| -rw-r--r-- | fg21sim/extragalactic/clusters/solver.py | 2 |
2 files changed, 26 insertions, 2 deletions
diff --git a/fg21sim/extragalactic/clusters/halo.py b/fg21sim/extragalactic/clusters/halo.py index 072cdff..6adfba5 100644 --- a/fg21sim/extragalactic/clusters/halo.py +++ b/fg21sim/extragalactic/clusters/halo.py @@ -447,6 +447,27 @@ class HaloSingle: Calculate the electron-acceleration coefficient at arbitrary redshift, by interpolating the coefficients calculated at every merger redshifts. + + Parameters + ---------- + z : float + Redshift where to calculate the acceleration coefficient. + + Returns + ------- + chi : float + The calculated electron-acceleration coefficient. + (unit: Gyr^-1) + + XXX/NOTE + -------- + This coefficient may be very small and even zero, then the + diffusion coefficient of the Fokker-Planck equation is thus + very small and even zero, which cause problems for calculating + some quantities (e.g., w(x), C(x)) and wrong/invalid results. + To avoid these problems, force the minimal value of this + coefficient to be 1/(10*t0), which t0 is the present-day age + of the universe. """ if not hasattr(self, "_coef_acceleration_interp"): # Order the merger events by decreasing redshifts @@ -454,9 +475,12 @@ class HaloSingle: redshifts = np.array([ev["z"] for ev in mevents]) chis = np.array([self._chi_at_zidx(zidx, mevents) for zidx in range(len(redshifts))]) + # XXX: force a minimal value instead of zero or too small + chi_min = 1.0 / (10 * self.cosmo.age0) + chis[chis < chi_min] = chi_min self._coef_acceleration_interp = scipy.interpolate.interp1d( redshifts, chis, kind="linear", - bounds_error=False, fill_value=0.0) + bounds_error=False, fill_value=chi_min) logger.info("Interpolated acceleration coefficients w.r.t. z") return self._coef_acceleration_interp(z) diff --git a/fg21sim/extragalactic/clusters/solver.py b/fg21sim/extragalactic/clusters/solver.py index c1f01d1..9d4a781 100644 --- a/fg21sim/extragalactic/clusters/solver.py +++ b/fg21sim/extragalactic/clusters/solver.py @@ -58,7 +58,7 @@ class FokkerPlanckSolver: u(x,t) : distribution/spectrum w.r.t. x at different times B(x,t) : advection coefficient - C(x,t) : diffusion coefficient (>=0) + C(x,t) : diffusion coefficient (>0) Q(x,t) : injection coefficient (>=0) References |