Intrinsic spectra of the AXPs

  • Martin DurantEmail author
Conference paper


Using direct measurements of photo-electric absorption edges, I derive the intrinsic spectra for the Anomalous X-ray Pulsars. In the past, the hydrogen column density, NH had been found by fitting the X-ray spectra with a variety of simple continuum models. Since different models fit equally well, with different values of NH, little is learned about the true column density or intrinsic spectra. Here, I measure the column densities in a model-independent way, and thus derive intrinsic spectra without first assuming what those spectra ought to look like. Particularly for the brightest source, 4U 0142+61, the column density can be determined accurately, and is a factor of 1.4 smaller that the typically NH quoted. With this new value, the new intrinsic spectrum can be investigated anew, and shows a slight hint of a feature around 13 Å.

To be emphasised, this is an empirical method with the minimum of assumptions, as is appropriate for these beguiling sources, the behaviour of which has mystifies astronomers for over a decade.

This paper summarises the methods and conclusions to be published in the Astrophysical Journal by Durant and Van Kerkwijk (2006; see astro-ph/0606604).


Pulsars: anomalous X-ray pulsars Interstellar extinction X-ray spectroscopy 




Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.


  1. [Asplund et al., 2004]
    Asplund, M., Grevesse, N., Jacques Sauval, A.: In: Bash, F.N., Barnes, T.G. (eds.) Cosmic Abundances as Records of Stellar Evolution and Nucleosynthesis. ASP Conf. Ser. (2004) Google Scholar
  2. [den Hartog et al., 2006]
    den Hartog, P., Hermsen, W., Kuiper, L., et al.: Astron. Astrophys. 451, 587 (2006) ADSCrossRefGoogle Scholar
  3. [den Herder et al., 2001]
    den Herder, J., Brinkman, A., Kahn, S., et al.: Astron. Astrophys. 365, L7 (2001) ADSCrossRefGoogle Scholar
  4. [Durant and Van Kerkwijk, 2006a]
    Durant, M., Van Kerkwijk, M.: Astrophys. J. 650, 1082 (2006a) ADSCrossRefGoogle Scholar
  5. [Durant and Van Kerkwijk, 2006b]
    Durant, M., Van Kerkwijk, M.: Astrophys. J. 650, 1070 (2006b) ADSCrossRefGoogle Scholar
  6. [Durant and Van Kerkwijk, 2006c]
    Durant, M., Van Kerkwijk, M.: Astrophys. J., 652, 576 (2006c) ADSCrossRefGoogle Scholar
  7. [Hulleman et al., 2004]
    Hulleman, F., Van Kerkwijk, M., Kulkarni, S.: Astron. Astrophys. 416, 1037 (2004) ADSCrossRefGoogle Scholar
  8. [Jensen, 1999]
    Jensen, G.: Bull. Am. Astron. Soc. 32, 724 (1999) ADSGoogle Scholar
  9. [Juett et al., 2002]
    Juett, A., Marshall, H., Chakrabarty, D., et al.: Astrophys. J. 568, L31 (2002) ADSCrossRefGoogle Scholar
  10. [Juett et al., 2006]
    Juett, A., Schulz, N., Chakrabarty, D., et al.: Astrophys. J. 648, 1066 (2006) ADSCrossRefGoogle Scholar
  11. [Lyutikov and Gavriil, 2006]
    Lyutikov, M., Gavriil, F.: Mon. Not. Roy. Astron. Soc. 368, 690 (2006) ADSCrossRefGoogle Scholar
  12. [Predehl and Schmitt, 1995]
    Predehl, W., Schmitt, S.A.: Astron. Astrophys. 293, 889 (1995) ADSGoogle Scholar
  13. [Press et al., 1992]
    Press, W., Teukolsky, S.A., Vetterling, W., et al.: Numerical Recipes: The Art of Scientific Computing, 2nd edn. Cambridge University Press (1992) Google Scholar
  14. [Takei et al., 2002]
    Takei, Y., Fujimoto, R., Mitsuda, K., et al.: Astrophys. J. 581, 307 (2002) ADSCrossRefGoogle Scholar
  15. [Ueda et al., 2005]
    Ueda, Y., Mitsuda, K., Murakami, H., et al.: Astrophys. J. 620, 274 (2005) ADSCrossRefGoogle Scholar
  16. [Wang et al., 2006]
    Wang, Z., Chakrabarty, D., Kaplan, D.: Nature 440, 772 (2006) ADSCrossRefGoogle Scholar
  17. [Woods and Thompson, 2004]
    Woods, P., Thompson, C.: In: Lewin, W., Van der Klis, M. (eds.) Compact Stellar X-Ray Sources (2004) Google Scholar

Copyright information

© Springer 2007

Authors and Affiliations

  1. 1.Astronomy & AstrophysicsUniversity of TorontoTorontoCanada

Personalised recommendations