Multi-instrument X-ray monitoring of the January 2009 outburst from the recurrent magnetar candidate 1E 1547.0-5408

¹ Università degli Studi di Roma “Tor Vergata” via Orazio Raimondo 18, 00173 Roma, Italy
e-mail: bernardini@oa-roma.inaf.it
² INAF – Osservatorio Astronomico di Roma, via Frascati 33, 00040 Monteporzio Catone (Roma), Italy
³ Department of Physics, University of Padova, via Marzolo 8, 35131 Padova, Italy
⁴ Mullard Space Science Laboratory University College London, Holmbury St Mary, Dorking, Surrey, RH5 6NT, UK
⁵ INAF – Osservatorio Astronomico di Cagliari, Localitá Poggio dei Pini, strada 54, 09012 Capoterra, Italy
⁶ Institut de Ciencies de l’Espai (ICE, CSIC-IEEC), 08193 Barcelona, Spain
⁷ INAF – Istituto di Astrofisica Spaziale e Fisica Cosmica Milano, via Edoardo Bassini 15, 20133 Milano, Italy
⁸ INAF – Osservatorio Astronomico di Brera, via Bianchi 46, 23807 Merate (Lc), Italy
⁹ AIM (UMR 7158 CEA/DSM-CNRS-Université Paris Diderot) Irfu/Service d’Astrophysique, Saclay, 91191 Gif-sur-Yvette Cedex, France
¹⁰ INAF – IASF Palermo via Ugo La Malfa 153, 90146 Palermo, Italy

Received: 24 November 2010
Accepted: 19 February 2011

Abstract

Context. With two consecutive outbursts recorded in four months (October 2008 and January 2009), and a possible third outburst in 2007, 1E 1547.0-5408 is one of the most active transient anomalous X-ray pulsars known so far.

Aims. Thanks to extensive X-ray observations, obtained both in the quiescent and active states, 1E 1547.0-5408 represents a very promising laboratory to gain insight into the outburst properties and magnetar emission mechanisms.

Methods. We performed a detailed timing and spectral analysis of four Chandra, three INTEGRAL, and one XMM-Newton observations collected over a two week interval after the outburst onset in January 2009. Several Swift pointings, covering a 1.5 year interval, were also analyzed in order to monitor the decay of the X-ray flux.

Results. We compare the characteristics of the two outbursts, as well as those of the active and quiescent states. We also discuss the long-term X-ray flux history of 1E 1547.0-5408 since its first detection in 1980, and show that the source displays three flux levels: low, intermediate and high.