Changes in the X-Ray Emission from the Magnetar Candidate 1E 2259+586 during Its 2002 Outburst

By P. Woods, Victoria Kaspi, C. Thompson, F. Gavriil, H. Marshall, D. Chakrabarty, K. Flanagan, J. Heyl, Lars Hernquist. 2003

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An outburst of more than 80 individual bursts, similar to those seen from Soft Gamma Repeaters (SGRs), was detected from the anomalous X-ray pulsar (AXP) 1E 2259+586 in 2002 June. Coincident with this burst activity were gross changes in the pulsed flux, persistent flux, energy spectrum, pulse profile, and spin-down of the underlying X-ray source. We present Rossi X-Ray Timing Explorer and X-Ray Multi-Mirror Mission observations of 1E 2259+586 that show the evolution of the aforementioned source parameters during and following this episode and identify recovery timescales for each. Specifically, we observe an X-ray flux increase (pulsed and phase-averaged) by more than an order of magnitude having two distinct components. The first component is linked to the burst activity and decays within ~2 days, during which the energy spectrum is considerably harder than during the quiescent state of the source. The second component decays over the year following the glitch according to a power law in time with an exponent -0.22 ± 0.01. The pulsed fraction decreased initially to ~15% rms but recovered rapidly to the preoutburst level of ~23% within the first 3 days. The pulse profile changed significantly during the outburst and recovered almost fully within 2 months of the outburst. A glitch of size Δνmax/ν = (4.24 ± 0.11) × 10-6 was observed in 1E 2259+586, which preceded the observed burst activity. The glitch could not be well fitted with a simple partial exponential recovery. An exponential rise of ~20% of the frequency jump with a timescale of ~14 days results in a significantly better fit to the data; however, contamination from a systematic drift in the phase of the pulse profile cannot be excluded. A fraction of the glitch (~19%) was recovered in a quasi-exponential manner having a recovery timescale of ~16 days. The long-term postglitch spin-down rate decreased in magnitude relative to the preglitch value. The changes in the source properties of 1E 2259+586 during its 2002 outburst are shown to be qualitatively similar to changes seen during or following burst activity in two SGRs, thus further solidifying the common nature of SGRs and AXPs as magnetars. The changes in persistent emission properties of 1E 2259+586 suggest that the star underwent a plastic deformation of the crust that simultaneously impacted the superfluid interior (crustal and possibly core superfluid) and the magnetosphere. Finally, the changes in persistent emission properties coincident with burst activity in 1E 2259+586 enabled us to infer previous burst-active episodes from this and other AXPs. The nondetection of these outbursts by all-sky gamma-ray instruments suggests that the number of active magnetar candidates in our Galaxy is larger than previously thought.

Subfields: Astronomy and Astrophysics

View Paper: https://www.semanticscholar.org/paper/66724d9e8160d8672e5b8dc4e5e89ca397c45689

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Citations in the corpus

Discovery of Luminous Pulsed Hard X-Ray Emission from Anomalous X-Ray Pulsars 1RXS J1708–4009, 4U 0142+61, and 1E 2259+586 by INTEGRAL and RXTE (2006, methodology): “Woods et al. (2004) presented a comparison of the X-ray emission characteristics of 1E 2259+586 before, during, and after the 2002 June outburst using data from XMM-Newton and RXTE.”
Detection of 107 glitches in 36 southern pulsars (2012, background): “Most glitches have been observed in relatively young radio pulsars but they have also been observed in magnetars (Woods et al. 2004; Dib et al. 2007) and even in a millisecond pulsar (Cognard & Backer 2004).”
A study of 315 glitches in the rotation of 102 pulsars (2011, background): “The coincidence observed between glitches and enhancement in X-ray flux in a few magnetars (Woods et al. 2004; Israel et al. 2007; Dib et al. 2007), and particularly in the high magnetic field X-ray pulsar PSR J1846−0258 (Kuiper & Hermsen 2009; Livingstone, Kaspi & Gavriil 2010), seems to belong…”