Source code for lenstronomy.GalKin.cosmo

import lenstronomy.Util.constants as const
import numpy as np

__all__ = ['Cosmo']


[docs]class Cosmo(object): """ cosmological quantities """ def __init__(self, d_d, d_s, d_ds): """ :param d_d: angular diameter distance to the deflector :param d_s: angular diameter distance to the source :param d_ds: angular diameter distance between deflector and source """ if d_ds <= 0 or d_s <= 0 or d_d <=0: raise ValueError('input angular diameter distances Dd: %s, Ds: %s, Dds: %s are not suppored for a lens' ' model!' % (d_d, d_s, d_ds)) self.dd = float(d_d) # angular diameter distance from observer to deflector in physical Mpc self.ds = float(d_s) # angular diameter distance from observer to source in physical Mpc self.dds = float(d_ds) # angular diameter distance from deflector to source in physical Mpc
[docs] def arcsec2phys_lens(self, theta): """ converts are seconds to physical units on the deflector :param theta: angle observed on the sky in units of arc seconds :return: pyhsical distance of the angle in units of Mpc """ return theta * const.arcsec * self.dd
@property def epsilon_crit(self): """ returns the critical projected mass density in units of M_sun/Mpc^2 (physical units) """ const_SI = const.c**2 / (4*np.pi * const.G) # c^2/(4*pi*G) in units of [kg/m] conversion = const.Mpc / const.M_sun # converts [kg/m] to [M_sun/Mpc] pre_const = const_SI * conversion # c^2/(4*pi*G) in units of [M_sun/Mpc] Epsilon_Crit = self.ds / (self.dd * self.dds) * pre_const # [M_sun/Mpc^2] return Epsilon_Crit