Multiwavelength Observations of the Soft Gamma Repeater SGR 1900+14 during Its 2001 April Activation

Kouveliotou, C.; Tennant, Allyn F.; Woods, Peter; Weisskopf, Martin C.; Hurley, K.; Fender, R. P.; Garrington, S. T.; Patel, S.; Göǧüş, E.

doi:10.1086/323496

Cited by 63 publications

(66 citation statements)

References 16 publications

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“…We measure 2-10 keV rms pulse fractions of 18.1(10)%, 16.3(11)%, 13.6(15)%, and 12.9(12)% for the respective epochs of MJD TDB 52,018.113 (SAX), 52,021.324 (CXO), 52,029.591 (SAX), and 52,030.092 (CXO). Note that the measured CXO pulse fractions differ slightly from those reported in Kouveliotou et al (2001), who reported the pulse fractions in the 0.5-7.0 keV energy range. The pulse fraction of SGR 1900+14 increases significantly following the April 18 flare, and during the subsequent 11 days slowly declines, approaching its quiescent value.…”

Section: Pulse Profile and Fractioncontrasting

confidence: 90%

The 2001 April Burst Activation of SGR 1900+14: Pulse Properties and Torque

Woods

Kouveliotou

Göǧüş

et al. 2003

ApJ

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We report on observations of SGR 1900+14 made with the Rossi X-Ray Timing Explorer (RXTE) and BeppoSAX during the 2001 April burst activation of the source. Using these data, we measure the spin-down torque on the star and confirm earlier findings that the torque and burst activity are not directly correlated. We compare the X-ray pulse profile to the gamma-ray profile during the April 18 intermediate flare and show that (1) their shapes are similar and (1) the gamma-ray profile aligns closely in phase with the X-ray pulsations. The good phase alignment of the gamma-ray and X-ray profiles suggests that there was no rapid spin-down following this flare of the magnitude inferred for the August 27 giant flare. We discuss how these observations further constrain magnetic field reconfiguration models for the large flares of SGRs.

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Section: Pulse Profile and Fractioncontrasting

confidence: 90%

The 2001 April Burst Activation of SGR 1900+14: Pulse Properties and Torque

Woods

Kouveliotou

Göǧüş

et al. 2003

ApJ

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“…In quiescence, the X-ray spectrum of SGR 1900+14 is best fitted (Woods et al 1999) by the sum of a BB (kT ' 0:5 keV) and a power law ( photon index À ' 1:0-2.5). For this model, the column density is consistently measured at N H ' 2:5 ; 10 22 cm À2 (Woods et al 1999(Woods et al , 2001Kouveliotou et al 2001;Feroci et al 2003). However, the particular observation in which our bursts were recorded took place during a state of enhanced flux following the 2001 April 18 flare (Feroci et al 2003), in a so-called afterglow state.…”

Section: Bepposax Mecs and Pds Spectral Analysismentioning

confidence: 71%

Broadband X‐Ray Spectra of Short Bursts from SGR 1900+14

Feroci

Caliandro

Massaro

et al. 2004

ApJ

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We report on the X-ray spectral properties of 10 short bursts from SGR 1900+14 observed with the narrow-field instruments on board BeppoSAX in the hours following the intermediate flare of 2001 April 18. Burst durations are typically shorter than 1 s and often show significant temporal structure on timescales as short as $10 ms. Burst spectra from the MECS and PDS instruments were fitted across an energy range from 1.5 to above 100 keV. We fitted several spectral models and assumed N H values smaller than 5 ; 10 22 cm À2 , as derived from observations in the persistent emission. Our results show that the widely used optically thin thermal bremsstrahlung law provides acceptable spectral fits for energies higher than 15 keV but severely overestimates the flux at lower energies. Several years ago similar behavior was observed in short bursts from SGR 1806À20, suggesting that the rollover of the spectrum at low energies is a universal property of this class of sources. Alternative spectral models, such as two blackbodies or a cutoff power law, provide significantly better fits to the broadband spectral data and show that all 10 bursts have spectra consistent with the same spectral shape.

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“…The strongest of these "intermediate" flares was observed on April 18, 2001 from SGR 1900+14 [108,74]. It lasted about 40 s and showed pulsations at the NS rotation period, as in the tails of giant flares, but it lacked an initial spike.…”

Section: Bursts and Flaresmentioning

confidence: 99%

Pulsars and Magnetars

Mereghetti

2013

Braz J Phys

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The high-energy sources known as anomalous X-ray pulsars (AXPs) and soft γ-ray repeaters (SGRs) are well explained as magnetars: isolated neutron stars powered by their own magnetic energy. After explaining why it is generally believed that the traditional energy sources at work in other neutron stars (accretion, rotation, residual heat) cannot power the emission of AXPs/SGRs, I review the observational properties of the twenty AXPs/SGRs currently known and describe the main features of the magnetar model. In the last part of this review I discuss the recent discovery of magnetars with low external dipole field and some of the relations between AXPs/SGRs and other classes of isolated neutron stars.

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Multiwavelength Observations of the Soft Gamma Repeater SGR 1900+14 during Its 2001 April Activation

Cited by 63 publications

References 16 publications

The 2001 April Burst Activation of SGR 1900+14: Pulse Properties and Torque

The 2001 April Burst Activation of SGR 1900+14: Pulse Properties and Torque

Broadband X‐Ray Spectra of Short Bursts from SGR 1900+14

Pulsars and Magnetars

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