The effect of X-ray dust scattering on a bright burst from the magnetar 1E 1547.0-5408

A bright burst, followed by an X-ray tail lasting ˜10 ks, was detected during an XMM-Newton observation of the magnetar 1E 1547.0-5408 carried out on 2009 February 3. The burst, also observed by Swift/BAT, had a spectrum well fitted by the sum of two blackbodies with temperatures of ˜4 and 10 keV and a fluence in the 0.3-150 keV energy range of ˜10-5 erg cm-2. The X-ray tail had a fluence of ˜4 × 10-8 erg cm-2. Thanks to the knowledge of the distances and relative optical depths of three dust clouds between us and 1E 1547.0-5408, we show that most of the X-rays in the tail can be explained by dust scattering of the burst emission, except for the first ˜20-30 s. We point out that other X-ray tails observed after strong magnetar bursts may contain a non-negligible contribution due to dust scattering.