The dust-scattering X-ray rings of the anomalous X-ray pulsar 1e1547.0-5408

A. Tiengo, G. Vianello, P. Esposito, S. Mereghetti, A. Giuliani, E. Costantini, G. L. Israel, L. Stella, R. Turolla, S. Zane, N. Rea, D. Götz, F. Bernardini, A. Moretti, P. Romano, M. Ehle, N. Gehrels

    Research output: Contribution to journalArticlepeer-review


    On 2009 January 22 numerous strong bursts were detected from the anomalous X-ray pulsar 1E1547.0-5408. Swift/XRT and XMM-Newton/EPIC observations carried out in the following two weeks led to the discovery of three X-ray rings centered on this source. The ring radii increased with time following the expansion law expected for a short impulse of X-rays scattered by three dust clouds. Assuming different models for the dust composition and grain size distribution, we fit the intensity decay of each ring as a function of time at different energies, obtaining tight constraints on the distance of the X-ray source. Although the distance strongly depends on the adopted dust model, we find that some models are incompatible with our X-ray data, restricting to 4-8 kpc the range of possible distances for 1E1547.0-5408. The best-fitting dust model provides a source distance of 3.91 ± 0.07 kpc, which is compatible with the proposed association with the supernova remnant G327.24-0.13, and implies distances of 2.2 kpc, 2.6 kpc and 3.4 kpc for the dust clouds, in good agreement with the dust distribution inferred by CO line observations toward 1E1547.0-5408. However, dust distances in agreement with CO data are also obtained for a set of similarly well-fitting models that imply a source distance of 5 kpc. A distance of ∼4-5 kpc is also favored by the fact that these dust models are already known to provide good fits to the dust-scattering halos of bright X-ray binaries. Assuming N H = 1022 cm -2 in the dust cloud responsible for the brightest ring and a bremsstrahlung spectrum with kT = 100keV, we estimate that the burst producing the X-ray ring released an energy of 1044-1045 erg in the 1-100 keV band, suggesting that this burst was the brightest flare without any long-lasting pulsating tail ever detected from a magnetar.

    Original languageEnglish (US)
    Pages (from-to)227-235
    Number of pages9
    JournalAstrophysical Journal
    Issue number1
    StatePublished - 2010


    • Dust, extinction
    • Stars: neutron
    • X-rays: individual (1E 1547.05408)
    • X-rays: stars

    ASJC Scopus subject areas

    • Astronomy and Astrophysics
    • Space and Planetary Science


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