losextinction.py 文件源码

def mm83(self, nh, waves):
        """X-ray extinction in the ISM from Morisson & McCammon 1983."""
        y = np.array([self.H_C_CGS / (x * self.ANG_CGS * self.KEV_CGS)
                      for x in waves])
        i = np.array([np.searchsorted(self._mm83[:, 0], x) - 1 for x in y])
        al = [1.0e-24 * (self._mm83[x, 1] + self._mm83[x, 2] * y[j] +
                         self._mm83[x, 3] * y[j] ** 2) / y[j] ** 3
              for j, x in enumerate(i)]
        # For less than 0.03 keV assume cross-section scales as E^-3.
        # http://ned.ipac.caltech.edu/level5/Madau6/Madau1_2.html
        # See also Rumph, Boyer, & Vennes 1994.
        al = [al[j] if x < self._min_xray
              else self._almin * (self._min_xray / x) ** 3
              for j, x in enumerate(y)]
        al = [al[j] if x > self._max_xray
              else self._almax * (self._max_xray / x) ** 3
              for j, x in enumerate(y)]
        return nh * np.array(al)