<i>Hubble Space Telescope</i>Observations of SGR 0526−66: New Constraints on Accretion and Magnetar Models

Kaplan, David L.; Kulkarni, S. R.; Kerkwijk, M. H. van; Rothschild, R. E.; Lingenfelter, R.; Marsden, D.; Danner, R.; Murakami, T.

doi:10.1086/323516

Cited by 41 publications

(42 citation statements)

References 49 publications

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“…These are the best limits to quiescent optical/IR emission from an SGR. In particular, in Kaplan et al (2001) we investigated F XR , the ratio of the integrated flux in the X-ray band (i.e., f ) to that in the optical R band. As noted by Hulleman, van Kerkwijk, & Kulkarni (2000), AXPs are distinguished by an unusually large F XR $ 10 4 .…”

Section: Discussionmentioning

confidence: 99%

The Quiescent Counterpart of the Soft Gamma‐Ray Repeater SGR 0526−66

Kulkarni

Kaplan

Marshall

et al. 2003

ApJ

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106

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It is now commonly believed that soft gamma-ray repeaters (SGRs) and anomalous X-ray pulsars (AXPs) are magnetars-neutron stars powered by their magnetic fields. However, what differentiates these two seemingly dissimilar objects is, at present, unknown. We present Chandra observations of RX J052600.3À660433, the quiescent X-ray counterpart of SGR 0526À66, famous for the intense burst of 1979 March 5. The source is unresolved at the resolution of Chandra. Restricting observations to a period range around 8 s, the period noted in the afterglow of the burst of 1979 March 5, we find evidence for a similar periodicity in two epochs of data obtained 20 months apart. The secular period derivative based on these two observations is 6:6ð5Þ Â 10 À11 s s À1 , similar to the period derivatives of the magnetars. As is the case with other magnetars, the spectrum is best fitted by a combination of a blackbody and a power law. However, quite surprisingly, the photon index of the power-law component is À $ 3-intermediate to those of AXPs and SGRs. This continuum of C led us to suggest that the underlying physical parameter that differentiates SGRs from AXPs is manifested in the power-law component. Two decades ago, SGR 0526À66 was a classical SGR, whereas now it behaves like an AXP. Thus, it is possible that the same object cycles between the SGR and AXP states. We speculate that the main difference between AXPs and SGRs is the geometry of the B fields, and this geometry is time dependent. Finally, given the steep spectrum of RX J052600.3À660433, the total radiated energy of RX J052600.3À660433 can be much higher than traditionally estimated. If this energy is supplied by the decay of the magnetic field, then the inferred B field of RX J052600.3À660433 is in excess of 10 15 G, the traditional value for magnetars. Independent of this discussion, there could well be a class of neutron stars, 10 14 GdBd10 15 G, which are neither radio pulsars nor magnetars.

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Section: Discussionmentioning

confidence: 99%

The Quiescent Counterpart of the Soft Gamma‐Ray Repeater SGR 0526−66

Kulkarni

Kaplan

Marshall

et al. 2003

ApJ

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106

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“…The source position for the knot is J2000 ¼ 05 h 25 m 529 53, J2000 ¼ À66 05 0 13>5, and the ACIS astrometric uncertainty at $6 0 off-axis is generally d2 00 (e.g., Feigelson et al 2002). The Chandra/ACIS position of SGR 0526À66 based on the on-axis data has a conservative astrometric uncertainty of d2>3 (Kaplan et al 2001 and references therein). The position of the SGR of our off-axis data as determined by wavdetect algorithm is offset $1>8 from the on-axis SGR position.…”

Section: Extended Feature Beyond the Shock Boundarymentioning

confidence: 99%

X‐Ray Emission from Multiphase Shock in the Large Magellanic Cloud Supernova Remnant N49

Park

Burrows

Garmire

et al. 2003

ApJ

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The supernova remnant (SNR) N49 in the Large Magellanic Cloud has been observed with the Advanced CCD Imaging Spectrometer (ACIS) on board the Chandra X-Ray Observatory. The superb angular resolution of the Chandra/ACIS images resolves a point source, the likely X-ray counterpart of soft gammaray repeater SGR 0526À66, and the diffuse filaments and knots across the SNR. These filamentary features represent the blast wave sweeping through the ambient interstellar medium and nearby dense molecular clouds. We detect metal-rich ejecta beyond the main blast wave shock boundary in the southwest of the SNR, which appear to be explosion fragments, or '' bullets,'' ejected from the progenitor star. The detection of strong H-like Si line emission in the eastern side of the SNR requires multiphase shocks in order to describe the observed X-ray spectrum, whereas such a multiphase plasma is not evident in the western side. This complex spectral structure of N49 suggests that the postshock regions toward the east of the SNR might have been reheated by the reverse shock off the dense molecular clouds while the blast wave shock front has decelerated as it propagates into the dense clouds. The X-ray spectrum of the detected pointlike source is continuum-dominated and can be described with a power law of À $ 3. This provides a confirmation that this pointlike X-ray source is the counterpart of SGR 0526À66 in the quiescent state.

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“…Chatterjee et al (2000) (see also van Paradijs et al, 1995;Corbet et al, 1995) proposed that AXPs are accreting from a fossil disk made of fall-back material from the supernova. However, this model overpredicts the observed optical/IR flux from the disk (Perna et al, 2000;Hulleman et al, 2000a,b;Kaplan et al, 2001). Thompson and Duncan (1996) suggested that the main source of free energy for AXP emission is from the magnetic field itself.…”

Section: Introductionmentioning

confidence: 96%