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Magnetar-like X-ray bursts from an anomalous X-ray pulsar


Anomalous X-ray pulsars (AXPs) are a class of rare X-ray emitting pulsars whose energy source has been perplexing for some 20 years1,2,3. Unlike other X-ray emitting pulsars, AXPs cannot be powered by rotational energy or by accretion of matter from a binary companion star, hence the designation ‘anomalous’. Many of the rotational and radiative properties of the AXPs are strikingly similar to those of another class of exotic objects, the soft-γ-ray repeaters (SGRs). But the defining property of the SGRs—their low-energy-γ-ray and X-ray bursts—has not hitherto been observed for AXPs. Soft-γ-ray repeaters are thought to be ‘magnetars’, which are young neutron stars whose emission is powered by the decay of an ultra-high magnetic field4,5; the suggestion that AXPs might also be magnetars has been controversial6. Here we report two X-ray bursts, with properties similar to those of SGRs, from the direction of the anomalous X-ray pulsar 1E1048.1 - 5937. These events imply a close relationship (perhaps evolutionary) between AXPs and SGRs, with both being magnetars.

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Figure 1: Light curves for the observed bursts.
Figure 2: X-ray spectrum in the 2–40 keV range for the 1 s after the onset of burst 1.


  1. Fahlman, G. G. & Gregory, P. C. An X-ray pulsar in SNR G109.1–1.0. Nature 293, 202–204 (1981)

    ADS  CAS  Article  Google Scholar 

  2. van Paradijs, J., Taam, R. E. & van den Heuvel, E. P. J. On the nature of the ‘anomalous’ 6-s X-ray pulsars. Astron. Astrophys. 299, L41–L44 (1995)

    ADS  CAS  Google Scholar 

  3. Mereghetti, S. & Stella, L. The very low mass X-ray binary pulsars: A new class of sources? Astrophys. J. 442, L17–L20 (1995)

    ADS  Article  Google Scholar 

  4. Thompson, C. & Duncan, R. C. The soft gamma repeaters as very strongly magnetized neutron stars—I. Radiative mechanism for outbursts. Mon. Not. R. Astron. Soc. 275, 255–300 (1995)

    ADS  Article  Google Scholar 

  5. Kouveliotou, C. et al. An X-ray pulsar with a superstrong magnetic field in the soft γ-ray repeater SGR 1806–20. Nature 393, 235–237 (1998)

    ADS  CAS  Article  Google Scholar 

  6. Chatterjee, P., Hernquist, L. & Narayan, R. An accretion model for anomalous X-ray pulsars. Astrophys. J. 534, 373–379 (2000)

    ADS  Article  Google Scholar 

  7. Thompson, C. & Duncan, R. C. The soft gamma repeaters as very strongly magnetized neutron stars. II. Quiescent neutrino, x-ray, and Alfven wave emission. Astrophys. J. 473, 322–342 (1996)

    ADS  CAS  Article  Google Scholar 

  8. Jahoda, K. et al. In-orbit performance and calibration of the Rossi X-ray Timing Explorer (RXTE) proportional counter array (PCA). Proc. SPIE 2808, 59–70 (1996)

    ADS  CAS  Article  Google Scholar 

  9. Kaspi, V. M., Chakrabarty, D. & Steinberger, J. Phase-coherent timing of two anomalous X-ray pulsars. Astrophys. J. 525, L33–L36 (1999)

    ADS  CAS  Article  Google Scholar 

  10. Kaspi, V. M., Lackey, J. R. & Chakrabarty, D. A glitch in an anomalous X-ray pulsar. Astrophys. J. 537, L31–L34 (2000)

    ADS  CAS  Article  Google Scholar 

  11. Kaspi, V. M., Gavriil, F. P., Chakrabarty, D., Lackey, J. R. & Muno, M. P. Long-term RXTE monitoring of the anomalous X-ray pulsar 1E 1048.1-5973. Astrophys. J. 558, 253–262 (2001)

    ADS  Article  Google Scholar 

  12. Gavriil, F. P. & Kaspi, V. M. Long-Term Rossi X-Ray Timing Explorer monitoring of anomalous X-ray pulsars. Astrophys. J. 567, 1067–1076 (2002)

    ADS  Article  Google Scholar 

  13. Lewin, W. H. G., Van Paradijs, J. & Taam, R. E. X-ray Binaries (eds Lewin, W. H. G.van Paradijs, J. & van den Heuvel, E. P. J.) 175–232 (Cambridge Univ. Press, Cambridge, 1995)

    Google Scholar 

  14. Liu, Q. Z., van Paradijs, J. & van den Heuvel, E. P. J. A catalogue of low-mass X-ray binaries. Astron. Astrophys. 368, 1021–1054 (2001)

    ADS  Article  Google Scholar 

  15. Heise, J., in't Zand, J., Kippen, M. & Woods, P. X-ray flashes and X-ray rich gamma-ray bursts. Mem. Soc. Astron. Ital. (in the press); preprint astro-ph0111246 at 〈〉 (2001).

  16. Stern, B. E., Tikhomirova, Y., Kompaneets, D., Svensson, R. & Poutanen, J. An off-line scan of the BATSE daily records and a large uniform sample of gamma-ray bursts. Astrophys. J. 563, 80–94 (2001)

    ADS  Article  Google Scholar 

  17. Fishman, G. J. et al. Overview of observations from BATSE on the Compton observatory. Astron. Astrophys. Suppl. 97, 17–20 (1993)

    ADS  CAS  Google Scholar 

  18. Göǧüs¸, E. et al. Temporal and spectral characteristics of short bursts from the soft gamma repeaters 1806-20 and 1900 + 14. Astrophys. J. 558, 228–236 (2001)

    ADS  Article  Google Scholar 

  19. Ibrahim, A. I. et al. An unusual burst from soft gamma repeater SGR 1990 + 14: Comparisons with giant flares and implications for the magnetar model. Astrophys. J. 558, 237–252 (2001)

    ADS  CAS  Article  Google Scholar 

  20. Strohmayer, T. E. & Ibrahim, A. I. Discovery of a 6.4 keV emission line in a burst from SGR 1900 + 14. Astrophys. J. 537, L111–L114 (2000)

    ADS  CAS  Article  Google Scholar 

  21. Woods, P. M. et al. Evidence for a sudden magnetic field reconfiguration in soft gamma repeater 1900 + 14. Astrophys. J. 552, 748–755 (2001)

    ADS  Article  Google Scholar 

  22. Pivovaroff, M., Kaspi, V. M. & Camilo, F. X-ray observations of the high magnetic field radio pulsar PSR J1814–1744. Astrophys. J. 535, 379–384 (2000)

    ADS  Article  Google Scholar 

  23. Gotthelf, E. V., Vasisht, G. & Dotani, T. On the spin history of the X-ray pulsar in Kes 73: Further evidence for an ultramagnetized neutron star. Astrophys. J. 522, L49–L52 (1999)

    ADS  Article  Google Scholar 

  24. Gaensler, B. M., Slane, P. O., Gotthelf, E. V. & Vasisht, G. Anomalous X-ray pulsars and soft gamma-ray repeaters in supernova remnants. Astrophys. J. 559, 963–972 (2001)

    ADS  Article  Google Scholar 

  25. Tiengo, A., Göhler, E., Staubert, R. & Mereghetti, S. The anomalous X-ray pulsar 1E 1048.1-5937: Phase resolved spectroscopy with the XMM-Newton satellite. Astron. Astrophys. 383, 182–187 (2002)

    ADS  Article  Google Scholar 

  26. Arnaud, K. A. Astronomical Data Analaysis Software and Systems V (eds Jacoby, G. & Barnes, J.) 17 (ASP, San Fransisco, 1996)

    Google Scholar 

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P.M.W. is affiliated to the Universities Space Research Association. We thank E. Kuulkers, K. Hurley, K. Jahoda, C. Kouveliotou, W. Lewin, M. Lyutikov, M. Muno, D. Psaltis, S. Ransom, M. Roberts, D. Smith and C. Thompson for discussions. This work was supported in part by a NASA LTSA grant, an NSERC research grant, and an NSF career award. V.M.K. is a Canada Research Chair and an Alfred P. Sloan Fellow. This work made use of data obtained through the High Energy Astrophysics Science Archive Research Center Online Service, provided by the NASA/Goddard Space Flight Center.

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Gavriil, F., Kaspi, V. & Woods, P. Magnetar-like X-ray bursts from an anomalous X-ray pulsar. Nature 419, 142–144 (2002).

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