Precise Localization of the Soft Gamma Repeater SGR 1627–41 and the Anomalous X-Ray Pulsar AXP 1E1841–045 with Chandra

University of California, Berkeley, Berkeley, California, United States
The Astrophysical Journal (Impact Factor: 6.28). 12/2008; 615(2):887. DOI: 10.1086/424704
Source: arXiv

ABSTRACT We present precise localizations of AXP 1E1841-045 and SGR 1627-41 with Chandra. We obtained new infrared observations of SGR 1627-41 and reanalyzed archival observations of AXP 1E1841-045 in order to refine their positions and search for infrared counterparts. A faint source is detected inside the error circle of AXP 1E1841-045. In the case of SGR 1627-41, several sources are located within the error radius of the X-ray position, and we discuss the likelihood of one of them being the counterpart. We compare the properties of our candidates to those of other known anomalous X-ray pulsar (AXP) and soft gamma repeater (SGR) counterparts. We find that the counterpart candidates for SGR 1627-41 and SGR 1806-20 would have to be intrinsically much brighter than AXPs in order to have counterparts detectable with the observational limits currently available for these sources. To confirm the reported counterpart of SGR 1806-20, we obtained new infrared observations during the 2003 July burst activation of the source. No brightening of the suggested counterpart is detected, implying that the counterpart of SGR 1806-20 remains yet to be identified.


Available from: Patrice Bouchet, May 27, 2015
  • [Show abstract] [Hide abstract]
    ABSTRACT: To date, the observational determination of braking indexes of magnetars is still an open question due to the lack of long-term radio emission and strong timing noise. Based on the assumption that the real ages of magnetars are the ages of their host supernova remnants (SNRs), expanding diffuse gaseous nebulae resulting from explosions of massive stars, we obtain the sizes of the braking index n for 11 magnetar candidates with SNRs. According to our calculations, the magnetar braking indexes will be constrained within the range of about 1–40, assuming the measurements of SNRs are reliable. We also investigate the frequency parameters of magnetars with associated SNRs, and estimate possible wind luminosities for magnetars with n < 3 and magnetic field decay rates for magnetars with n > 3. (© 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)
    Astronomische Nachrichten 08/2014; 335(6‐7). DOI:10.1002/asna.201412088 · 1.12 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: We report new spectral and temporal observations of the magnetar 1E 1841-045 in the Kes 73 supernova remnant obtained with the Nuclear Spectroscopic Telescope Array (NuSTAR). Combined with new Swift and archival XMM-Newton and Chandra observations, the phase-averaged spectrum is well characterized by a blackbody plus double power-law model, in agreement with previous, multi-mission X-ray results. However, we are unable to reproduce the spectral results reported using Suzaku observations. The pulsed fraction of the source is found to increase with photon energy. The measured rms pulsed fraction is ~12% and ~17% at ~20 keV and ~50 keV, respectively. We detect a new feature in the 24--35 keV band pulse profile that is uniquely double-peaked. This feature may be associated with a possible absorption or emission feature in the phase-resolved spectrum. We fit the X-ray data using the recently developed electron-positron outflow model of Beloborodov (2013) for the hard X-ray emission from magnetars. This produces a satisfactory fit allowing a constraint on the angle between the rotation and magnetic axes of the neutron star of ~20 degrees and on the angle between the rotation axis and line-of-sight of ~50 degrees. In this model, the soft X-ray component is inconsistent with a single blackbody; adding a second blackbody or a power-law component fits the data. The two-blackbody interpretation suggests a hot spot of temperature kT~0.9 keV occupying ~1% of the stellar surface.
    The Astrophysical Journal 10/2013; 779(2). DOI:10.1088/0004-637X/779/2/163 · 6.28 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: We present a Chandra and XMM-Newton study of the supernova remnant (SNR) Kes 73 hosting the anomalous X-ray pulsar 1E 1841-045. The Chandra image reveals clumpy structures across the remnant with enhanced emission along the western rim. The X-ray emission fills the radio shell and spatially correlates with the infrared image. The global X-ray spectrum is described by a two-component thermal model with a column density N_H ~ 2.6e22 cm^{-2} and a total luminosity of L_X ~ 3.3e37 ergs/s (0.5-10 keV, at an assumed distance of 8.5 kpc). The soft component is characterized by a temperature kT_s ~ 0.5 keV, a high ionization timescale, and enhanced Si and S abundances suggesting emission that is dominated by shocked ejecta. The hard component has a temperature kT_h ~ 1.6 keV, a relatively low ionization timescale, and mostly solar abundances suggesting emission that is dominated by interstellar/circumstellar shocked material. A spatially resolved spectroscopy study reveals no significant variations in the spectral properties. We infer an SNR age ranging between 750 yr and 2100 yr, an explosion energy of ~0.3e51 ergs and a shock velocity of 1200 km/s (under the Sedov phase assumption). We also discuss the possible scenario for Kes 73 expanding into the late red supergiant wind phase of its massive progenitor. Comparing the inferred metal abundances to core-collapse nucleosynthesis model yields, we estimate a progenitor mass >20 solar masses, adding a candidate to the growing list of highly magnetized neutron stars proposed to be associated with very massive progenitors.
    The Astrophysical Journal 11/2013; 781(1). DOI:10.1088/0004-637X/781/1/41 · 6.28 Impact Factor