XMM–Newton observations of soft gamma-ray repeaters

Mereghetti, S.; Esposito, P.; Tiengo, A.

doi:10.1007/s10509-007-9384-0

Cited by 24 publications

(35 citation statements)

References 68 publications

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“…A Similar flux decrease have been observed from its radio afterglow Taylor et al 2005) and its newly discovered IR counterpart Rea et al 2005a;Mereghetti et al 2007). …”

Section: Introductionsupporting

confidence: 79%

“…Our data set consists of about 700 individual pointings, but due to the faintness of the source we could not extract the spectra from the individual pointings. We extracted the images for each pointing in 10 energy bands between 20 and 300 keV and added all the individual images in order to produce two mosaics (one for each 7 Note that here we use a different definition of the pulsed fraction than in Mereghetti et al (2007). Using the old definition based on a sinusoidal fit to the profile, the estimated pulsed fraction in the same energy range is (8 ± 1)%.…”

Section: Integral Observations and Broad-band Spectral Analysismentioning

confidence: 99%

“…Under the assumption of pure magnetic dipole braking, these values imply a surface magnetic field strength of 8×10 14 G, strongly supporting the magnetar model. Both the burst rate and the X-ray persistent emission of SGR 1806−20 started increasing during 2003 and throughout 2004 (Mereghetti et al 2005c;Tiengo et al 2005;Mereghetti et al 2007;Woods et al 2007), culminating with the giant flare of December 27, 2004, during which ∼10 47 erg were released 1 (Hurley et al 2005;Mereghetti et al 2005b;Terasawa et al 2005). This giant flare was exceptionally intense, ∼100 times more energetic than those from SGR 0526−66 and SGR 1900+14.…”

Section: Introductionmentioning

confidence: 99%

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SGR 1806-20 about two years after the giant flare:Suzaku,XMM-Newton andINTEGRAL observations

Esposito

Mereghetti

Tiengo

et al. 2007

A&A

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In December 2004, the soft gamma-ray repeater SGR 1806−20 emitted the most powerful giant flare ever observed. This probably involved a large-scale rearrangement of the magnetosphere leading to observable variations in the properties of its X-ray emission. Here we present the results of the first Suzaku observation of SGR 1806−20, together with almost simultaneous observations with XMM-Newton and INTEGRAL. The source seems to have reached a state characterized by a flux close to the pre-flare level and by a relatively soft spectrum. Despite this, SGR 1806−20 also remained quite active after the giant flare, allowing us to study several short bursts observed by Suzaku in the 1-100 keV range. We discuss the broad-band spectral properties of SGR 1806−20, covering both persistent and bursting emission, in the context of the magnetar model, and consider its recent theoretical developments.

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“…A Similar flux decrease have been observed from its radio afterglow Taylor et al 2005) and its newly discovered IR counterpart Rea et al 2005a;Mereghetti et al 2007). …”

Section: Introductionsupporting

confidence: 79%

Section: Integral Observations and Broad-band Spectral Analysismentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

SGR 1806-20 about two years after the giant flare:Suzaku,XMM-Newton andINTEGRAL observations

Esposito

Mereghetti

Tiengo

et al. 2007

A&A

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“…Nowadays, it is generally accepted that AXPs are powered by magnetic dissipation and that AXPs belong to the magnetar class (Duncan & Thompson 1992;Thompson & Duncan 1993Thompson et al 2002). To the magnetar class also belong Soft Gamma-ray Repeaters (SGRs) (Woods & Thompson 2006;Mereghetti et al 2007). So far, there are in total 13 confirmed magnetars known.…”

Section: Introductionmentioning

confidence: 99%

Detailed high-energy characteristics of AXP 1RXS J170849-400910

Hartog¹,

Kuiper²,

Hermsen

2008

A&A

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ABSTRACT1RXS J170849-400910 is one of four anomalous X-ray pulsars which emit persistent luminous radiation in soft X-rays (<10 keV) as well as in hard X-rays (>10 keV). In this paper we present detailed spectral and temporal characteristics over the whole X-ray band. For this purpose data have been used from INTEGRAL, RXTE and XMM-Newton. The hard X-ray (>10 keV) time-averaged total spectrum, accumulated over four years with the imager IBIS-ISGRI onboard INTEGRAL adding up to 5.2 Ms net exposure, can be described by a power law with a photon index Γ = 1.13 ± 0.06 and extends to ∼175 keV. The 20−175 keV flux is (7.76 ± 0.34) × 10 −11 erg cm −2 s −1 which exceeds the 2−10 keV (unabsorbed) flux by a factor of ∼2.3. No evidence for a spectral break is found below 300 keV. Also, no significant long-term time variability has been detected above 20 keV on time scales of 1 and 0.5 year. Pulsed emission is measured with INTEGRAL up to 270 keV, i.e. to much higher energies than the total emission, with a detection significance of 12.3σ (20−270 keV). The pulse profiles from 0.5 keV up to 270 keV show drastic morphology changes below ∼20 keV. Three different pulse components can be recognized in these pulse profiles: 1) a hard pulse peaking around phase 0.8 which contributes to the pulse profiles above ∼4 keV; 2) a softer pulse which peaks around phase 0.4 not contributing in the hard X-ray domain and 3) a very soft pulse component below 2 keV. A combined time-averaged pulsed spectrum (2.8−270 keV) from INTEGRAL, RXTE-PCA and HEXTE (collected over nine years) can be described with a soft and a hard power-law component: Γ s = 2.79 ± 0.07 and Γ h = 0.86 ± 0.16. In the pulsed spectrum extracted from a 25.5 ks net exposure XMM-Newton observation we find a discontinuity between 2 keV and 3 keV. Above these energies the spectrum is consistent with the spectrum taken with RXTE-PCA. The pulse profiles and the total-pulsed spectrum prove to be stable over the whole nine-years time span over which the data have been taken. Also detailed phase-resolved spectroscopy of the pulsed emission confirms the long-term stability as the spectra taken at different epochs connect smoothly. The phase-resolved spectra reveal complex spectral shapes which do not follow the shape of the total-pulsed spectrum. The spectral shape gradually changes with phase from a soft single power law to a complex multi-component shape and then to a hard single power law. The spectrum switches from a very hard (Γ = 0.99 ± 0.05) to a very soft (Γ = 3.58 ± 0.34) single power-law shape within a 0.1-wide phase interval. The discontinuity measured between 2 keV and 3 keV with XMM-Newton is a result of a curved component. This component which is most apparent within phase interval 0.7−0.9 significantly contributes in the energy range between 4 keV and 20 keV. It has a very steep spectrum below 5 keV with a photon index Γ ∼ −1.5. From the phaseresolved spectra we identify three independent components with different spectral shapes which together can accurately describe all...

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“…The pulsed fraction was significantly smaller than before the flare and the spin-down rate decreased. The following observations (Esposito et al 2007a;Mereghetti et al 2007), during which bursts were again detected, indicate that the source is still active although the flux levelled to the 2003 value.…”

Section: Sgr 1806-20mentioning

confidence: 79%