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تسجيل مستخدم جديدVLT observations of the magnetar CXO J164710.2-455216 and the detection of a candidate infrared counterpart
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We present deep observations of the field of the magnetar CXOJ164710.2-455216 in the star cluster Westerlund 1, obtained in the near-infrared with the adaptive optics camera NACO@VLT. We detected a possible candidate counterpart at the {em Chandra} position of the magnetar, of magnitudes $mathrm{J} = 23.5 pm 0.2$, $mathrm{H} = 21.0 pm 0.1$, and $mathrm{K}_mathrm{S} = 20.4 pm 0.1$. The K$_{rm S}$-band measurements available for two epochs (2006 and 2013) do not show significant signs of variability but only a marginal indication that the flux varied (at the 2 $sigma$ level), consistent with the fact that the observations were taken when CXOJ164710.2-455216 was in quiescence. At the same time, we also present colour--magnitude and colour--colour diagrams in the J, H, and K$_{rm S}$ bands from the 2006 epoch only, the only one with observations in all three bands, showing that the candidate counterpart lies in the main bulk of objects describing a relatively well--defined sequence. Therefore, based on its colours and lack of variability, we cannot yet associate the candidate counterpart to CXOJ164710.2-455216. Future near-infrared observations of the field, following-up a source outburst, would be crucial to confirm the association from the detection of near-infrared variability and colour evolution.
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We report on data obtained with the Chandra, XMM-Newton, Suzaku and Swift X-ray observatories, following the 2006 outburst of the Anomalous X-ray Pulsar CXO J164710.2-455216. We find no evidence for the very large glitch and rapid exponential decay a
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We report results of X-ray timing analyses for the low-field magnetar CXOU~J164710.2$-$455216 which exhibited multiple outbursts. We use data taken with NICER, NuSTAR, Chandra, and Neil-Gehrels-Swift telescopes between 2017 and 2018 when the source w
as in an active state. We perform semi-phase-coherent timing analyses to measure the spin parameters and a spin-inferred magnetic-field strength ($B_s$) of the magnetar. Using a semi-phase-coherent method, we infer the magnetic field strengths to be $3-4times 10^{13}rm G$ at the observation period ($sim$MJD 58000), and by comparing with previous frequency measurements (MJD 54000) a long-term average value of $B_s$ is estimated to be $approx4times 10^{13}rm G$. So this analysis may add CXOU~J164710.2$-$455216 to the ranks of low-field magnetars. The inferred characteristic age ($tau_c$) is 1--2 Myr which is smaller than the age of Westerlund~1, so the magnetars association with the star cluster is still secure. For the low dipole field and the large age, recent multiple outbursts observed from the source are hard to explain unless it has strong magnetic multipole components. We also find timing anomalies around outburst epochs, which suggests that there may be spin-down torque applied to the magnetar near the epochs as was proposed in magnetar models.
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