The Prelude to and Aftermath of the Giant Flare of 2004 December 27: Persistent and Pulsed X‐Ray Properties of SGR 1806−20 from 1993 to 2005

Woods, Peter; Kouveliotou, C.; Finger, Mark H.; Göǧüş, E.; Wilson, C. A.; Patel, S.; Hurley, Kevin; Swank, J. H.

doi:10.1086/507459

Cited by 127 publications

(144 citation statements)

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“…We find no dependence, within error, in these two properties within the energy range considered. We extended the work of Woods et al (2007) and Y15 to build the most comprehensive view of the torque evolution of SGR 1806−20 from 1993 up to 2016. The middle panel of Figure 3 shows the timing history of SGR 1806−20 up to the last NuSTAR observation in April 2016, over 11 years after the giant flare.…”

Section: Timing Analysismentioning

confidence: 99%

“…The middle panel of Figure 3 shows the timing history of SGR 1806−20 up to the last NuSTAR observation in April 2016, over 11 years after the giant flare. The blue dots are data from Woods et al (2007), red dots are XMM-Newton data from Y15, while black dots are the frequencies as derived with NuSTAR. The lines represent average frequency derivative over periods of relatively stable spin.…”

Section: Timing Analysismentioning

confidence: 99%

“…This episode culminated with the emission of the strongest giant flare (GF) on record so far (Hurley et al 2005;Gaensler et al 2005), December 27th, 2004. Radical changes in the source temporal and spectral properties have been observed since 1995 with its X-ray spectral shape hardening gradually and its frequency derivative increasing monotonically up to 2002 Woods et al 2007). Around the time of the 2004 bursting episode and the giant flare, erratic changes to the timing properties of the source were observed (Woods et al 2007).…”

Section: Introductionmentioning

confidence: 99%

“…Radical changes in the source temporal and spectral properties have been observed since 1995 with its X-ray spectral shape hardening gradually and its frequency derivative increasing monotonically up to 2002 Woods et al 2007). Around the time of the 2004 bursting episode and the giant flare, erratic changes to the timing properties of the source were observed (Woods et al 2007). The 0.5-10 keV persistent flux from the source started increasing shortly before the major bursting episode of 2004, reaching a maximum around its peak activity.…”

Section: Introductionmentioning

confidence: 99%

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The Sleeping Monster: NuSTAR Observations of SGR 1806–20, 11 Years After the Giant Flare

Younes

Baring

Kouveliotou

et al. 2017

ApJ

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We report the analysis of 5 NuSTAR observations of SGR 1806−20 spread over a year from April 2015 to April 2016, more than 11 years following its Giant Flare (GF) of 2004. The source spin frequency during the NuSTAR observations follows a linear trend with a frequency derivativeν = (−1.25 ± 0.03) × 10 −12 Hz s −1 , implying a surface dipole equatorial magnetic field B ≈ 7.7×10 14 G. Thus, SGR 1806−20 has finally returned to its historical minimum torque level measured between 1993 and 1998. The source showed strong timing noise for at least 12 years starting in 2000, withν increasing one order of magnitude between 2005 and 2011, following its 2004 major bursting episode and GF. SGR 1806−20 has not shown strong transient activity since 2009 and we do not find short bursts in the NuSTAR data. The pulse profile is complex with a pulsed fraction of ∼ 8% with no indication of energy dependence. The NuSTAR spectra are well fit with an absorbed blackbody, kT = 0.62 ± 0.06 keV, plus a power-law, Γ = 1.33 ± 0.03. We find no evidence for variability among the 5 observations, indicating that SGR 1806−20 has reached a persistent and potentially its quiescent X-ray flux level after its 2004 major bursting episode. Extrapolating the NuSTAR model to lower energies, we find that the 0.5-10 keV flux decay follows an exponential form with a characteristic timescale τ = 543 ± 75 days. Interestingly, the NuSTAR flux in this energy range is a factor of ∼ 2 weaker than the long-term average measured between 1993 and 2003, a behavior also exhibited in SGR 1900 + 14. We discuss our findings in the context of the magnetar model.

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Section: Timing Analysismentioning

confidence: 99%

Section: Timing Analysismentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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The Sleeping Monster: NuSTAR Observations of SGR 1806–20, 11 Years After the Giant Flare

Younes

Baring

Kouveliotou

et al. 2017

ApJ

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“…Woods et al (2000) used a series of RXTE observations to investigate the spin evolution of SGR 1806-20 and found that SGR 1806-20 contains a significant timing noise. The spin history was refined by many investigations (e.g., Mereghetti et al 2000;Woods et al 2007). The latest long-term (years) spin history was reported by Younes et al (2015) with a spin-down rate of´-2.53 10 2 s yr −1 , which is larger than the historical values measured in 1995.…”

Section: Introductionmentioning

confidence: 99%

STUDYING THE SGR 1806-20/Cl* 1806-20 REGION USING THE FERMI LARGE AREA TELESCOPE

Yeung

Kong

Tam

et al. 2016

ApJ

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The region around SGR 1806-20 and its host stellar cluster Cl * 1806-20 is a potentially important site of particle acceleration. The soft γ-ray repeater and Cl * 1806-20, which also contains several very massive stars including a luminous blue variable hypergiant LBV 1806-20, are capable of depositing a large amount of energy to the surroundings. Using the data taken with the Fermi Large Area Telescope (LAT), we identified an extended LAT source to the southwest of Cl * 1806-20. The centroid of the 1-50 GeV emission is consistent with that of HESS J1808-204 (until now unidentified). The LAT spectrum is best-fit by a broken power law with the break energy =  E 297 15 MeV b . The index above E b is 2.60±0.04 and is consistent with the flux and spectral index above 100 GeV for HESS J1808-204, suggesting an association between the two sources. Meanwhile, the interacting supernova remnant SNR G9.7-0.0 is also a potential contributor to the LAT flux. A tentative flux enhancement at the MeV band during a 45 day interval (2011 January 21-March 7) is also reported. We discuss possible origins of the extended LAT source in the context of both leptonic and hadronic scenarios.

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On the connection between radiative outbursts and timing irregularities in magnetars

2019

Astron Nachr

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Magnetars are strongly magnetized pulsars and they occasionally show violent radiative outbursts. They also often exhibit glitches that are sudden changes in the spin frequency. It was found that some glitches were associated with outbursts but their connection remains unclear. We present a systematic study to identify possible correlations between them. We find that the glitch size of magnetars likely shows a bimodal distribution, different from the distribution of the Vela-like recurrent glitches but consistent with the high-end of that of normal pulsars. A glitch is likely a necessary condition for an outburst but not a sufficient condition because only 30% of glitches were associated with outbursts. In the outburst cases, the glitches tend to induce larger frequency changes compared to those unassociated ones. We argue that a larger glitch is more likely to trigger the outburst mechanism, either by reconfiguration of the magnetosphere or deformation of the crust. A more frequent and deeper monitoring of magnetars is necessary for further investigation of their connection.

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The Prelude to and Aftermath of the Giant Flare of 2004 December 27: Persistent and Pulsed X‐Ray Properties of SGR 1806−20 from 1993 to 2005

Cited by 127 publications

References 39 publications

The Sleeping Monster: NuSTAR Observations of SGR 1806–20, 11 Years After the Giant Flare

The Sleeping Monster: NuSTAR Observations of SGR 1806–20, 11 Years After the Giant Flare

STUDYING THE SGR 1806-20/Cl* 1806-20 REGION USING THE FERMI LARGE AREA TELESCOPE

On the connection between radiative outbursts and timing irregularities in magnetars

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