diff options
Diffstat (limited to 'fg21sim/utils/cosmology.py')
| -rw-r--r-- | fg21sim/utils/cosmology.py | 48 |
1 files changed, 48 insertions, 0 deletions
diff --git a/fg21sim/utils/cosmology.py b/fg21sim/utils/cosmology.py index cc347e4..ab9637d 100644 --- a/fg21sim/utils/cosmology.py +++ b/fg21sim/utils/cosmology.py @@ -38,6 +38,7 @@ import logging import numpy as np from scipy import integrate +from scipy import interpolate from astropy.cosmology import FlatLambdaCDM from .units import (UnitConversions as AUC, Constants as AC) @@ -119,9 +120,56 @@ class Cosmology: def H(self, z): """ Hubble parameter at redshift z. + Unit: [km/s/Mpc] """ return self.H0 * self.E(z) + def Dc(self, z): + """ + Comoving distance at redshift z. + Unit: [Mpc] + """ + return self._cosmo.comoving_distance(z).value + + def Dc_to_redshift(self, Dc, zmin=0, zmax=3, zstep=0.01): + """ + Calculate the redshifts corresponding to the given comoving + distances by interpolation. + + Parameters + ---------- + Dc : float, or `~numpy.ndarray` + Comoving distances + Unit: [Mpc] + zmin, zmax : float, optional + The minimum and maximum redshift within which the input + comoving distances are enclosed; otherwise, a error will be + raised during the calculation. + zstep : float, optional + The redshift step size adopted to do the interpolation. + + Returns + ------- + redshift : float, or `~numpy.ndarray` + Calculated redshifts w.r.t. the input comoving distances. + + Raises + ------ + ValueError : + The ``zmin`` or ``zmax`` is not enough to enclose the input + comoving distance range. + """ + Dc_min, Dc_max = self.Dc([zmin, zmax]) # [Mpc] + if np.sum(Dc < Dc_min) > 0: + raise ValueError("zmin=%s is too big for input Dc" % zmin) + if np.sum(Dc > Dc_max) > 0: + raise ValueError("zmax=%s is too small for input Dc" % zmax) + + z_ = np.arange(zmin, zmax+zstep/2, zstep) + Dc_ = self.Dc(z_) + Dc_interp = interpolate.interp1d(Dc_, z_, kind="linear") + return Dc_interp(Dc) + def DA(self, z): """ Angular diameter distance at redshift z. |