model.py 文件源码

def absolute_magnitude(self, richness=1, steps=1e4):
        """
        Calculate the absolute magnitude (Mv) by integrating the
        stellar luminosity.

        Parameters:
        -----------
        richness : isochrone normalization parameter
        steps    : number of isochrone sampling steps

        Returns:
        --------
        abs_mag : Absolute magnitude (Mv)
        """
        # Using the SDSS g,r -> V from Jester 2005 [arXiv:0506022]
        # for stars with R-I < 1.15
        # V = g_sdss - 0.59(g_sdss-r_sdss) - 0.01
        # g_des = g_sdss - 0.104(g_sdss - r_sdss) + 0.01
        # r_des = r_sdss - 0.102(g_sdss - r_sdss) + 0.02
        if self.survey.lower() != 'des':
            raise Exception('Only valid for DES')
        if 'g' not in [self.band_1,self.band_2]:
            msg = "Need g-band for absolute magnitude"
            raise Exception(msg)    
        if 'r' not in [self.band_1,self.band_2]:
            msg = "Need r-band for absolute magnitude"
            raise Exception(msg)    

        mass_init,mass_pdf,mass_act,mag_1,mag_2=self.sample(mass_steps = steps)
        g,r = (mag_1,mag_2) if self.band_1 == 'g' else (mag_2,mag_1)

        V = g - 0.487*(g - r) - 0.0249
        flux = np.sum(mass_pdf*10**(-V/2.5))
        Mv = -2.5*np.log10(richness*flux)
        return Mv