cosmo.py 文件源码

def norm_apec(self, z):
        """
        The normalization factor of the XSPEC APEC model assuming
        EM = 1 (i.e., n_e = n_H = 1 cm^-3, and V = 1 cm^3)

        norm = 1e-14 / (4*pi* (D_A * (1+z))^2) * int(n_e * n_H) dV
        unit: [cm^-5]

        This value will be used to calculate the cooling function values.

        References
        ----------
        * XSPEC: APEC model
          https://heasarc.gsfc.nasa.gov/docs/xanadu/xspec/manual/XSmodelApec.html
        """
        da = self.angular_diameter_distance(z, unit="cm")
        norm = 1e-14 / (4*math.pi * (da * (1+z))**2)
        return norm