cosmology.py 文件源码

def redshift(self, age):
        """
        Invert the above ``self.age(z)`` formula analytically, to calculate
        the redshift corresponding to the given cosmic time (age).

        Parameters
        ----------
        age : `~numpy.ndarray`
            Age of the universe (i.e., cosmic time)
            Unit: [Gyr]

        Returns
        -------
        z : `~numpy.ndarray`
            Redshift corresponding to the specified age.
        """
        age = np.asarray(age)
        t_H = self.hubble_time
        term1 = (1/self.Om0) - 1
        term2 = np.sinh(3*age * np.sqrt(1-self.Om0) / (2*t_H)) ** 2
        z = (term1 / term2) ** (1/3) - 1
        return z