Quiet but still bright: XMM-Newton observations of the soft gamma-ray repeater SGR 0526-66

Abstract

SGR 0526-66 was the first soft gamma-ray repeater (SGR) from which a giant flare was detected in March 1979, suggesting the existence of magnetars, i.e. neutron stars powered by the decay of their extremely strong magnetic field. Since then, very little information has been obtained on this object, mainly because it has been burst-inactive since 1983 and the study of its persistent X-ray emission has been hampered by its large distance and its location in a X-ray bright supernova remnant in the Large Magellanic Cloud. Here we report on a comprehensive analysis of all the available XMM-Newton observations of SGR 0526-66. In particular, thanks to a deep observation taken in 2007, we measured its pulsation period (P = 8.0544 +/- 0.0002 s) 6 years after its latest detection by Chandra. This allowed us to detect for the first time a significant reduction of its spin-down rate. From a comparison with two shorter XMM-Newton observations performed in 2000 and 2001, we found no significant changes in the spectrum, which is well modelled by an absorbed power-law with nH = 4.6E+21 cm^-2 and photon index = 3.27. The high luminosity (about 4E+35 erg/s, in the 1-10 keV energy band) still observed about 25 years after the latest detection of bursting activity places SGR 0526-66 in the group of bright and persistent magnetar candidates.

arXiv comment5 pages, 3 figures (1 color) and 2 tables; Accepted for publication in MNRAS Letters

References in corpus (12)

• The European Photon Imaging Camera on XMM-Newton: The MOS Cameras
• The strongest cosmic magnets: Soft Gamma-ray Repeaters and Anomalous X-ray Pulsars
• Electrodynamics of Magnetars: Implications for the Persistent X-ray Emission and Spindown of the Soft Gamma Repeaters and Anomalous X-ray Pulsars
• An exceptionally bright flare from SGR1806-20 and the origins of short-duration gamma-ray bursts
• A giant, periodic flare from the soft gamma repeater SGR1900+14
• Distances to Anomalous X-ray Pulsars using Red Clump Stars
• The Quiescent Counterpart of the Soft Gamma-ray Repeater SGR 0526-66
• A XMM-Newton View of the Soft Gamma-ray Repeater SGR 1806--20: Long Term Variability in the pre-Super Giant Flare Epoch
• Anomalous X-ray Pulsar 1E 1048.1-5937: Pulsed Flux Flares and Large Torque Variations
• The 2008 May burst activation of SGR 1627-41
• X-Ray Emission from Multi-Phase Shock in the Large Magellanic Cloud Supernova Remnant N49
• Supernova Remnants in the Large Magellanic Clouds IX: Multiwavelength Analysis of the Physical Structure of N49

Cited by in corpus (20)

• Magnetars
• The McGill Magnetar Catalog
• Formation Rates and Evolution Histories of Magnetars
• Magnetar outbursts: an observational review
• Constraining the Braking Indices of Magnetars
• Intermediate-Mass-Elements in Young Supernova Remnants Reveal Neutron Star Kicks by Asymmetric Explosions
• An X-Ray Study of Supernova Remnant N49 and Soft Gamma-Ray Repeater 0526-66 in the Large Magellanic Cloud
• Chandra observations of SGR 1627-41 near quiescence
• Constraining the Origin of Magnetar Flares
• Torsional Oscillations of a Magnetar with a Tangled Magnetic Field
• The impulsive phase of magnetar giant flares: assessing linear tearing as the trigger mechanism
• Long-term evolution of anomalous X-ray pulsars and soft gamma repeaters
• On the Origin of Radio Emission from Magnetars
• A systematic study of soft X-ray pulse profiles of magnetars in quiescence
• On the Cooling Trend of SGR 0526-66
• XMM-Newton Observations of Two Candidate Supernova Remnants
• NuSTAR Detection of Quiescent Hard X-Ray Emission from SGR 0526-66 in the Large Magellanic Cloud
• Tangled magnetic field model of QPOs
• Statistical ages and the cooling rate of X-ray dim isolated neutron stars
• Discovery of a magnetar candidate X-ray pulsar in the Large Magellanic Cloud