Long-term XMM-Newton view of magnetar CXOU J010043.1-721134: comprehensive spectral and temporal results

We present an in-depth analysis and results of eleven XMM-Newton data sets, spanning 2000-2016, of the anomalous X-ray Pulsar CXOU J010043.1-721134 that has been classified as a magnetar. We find a spin period of 8.0275(1) s as of December 2016 and calculate the period derivative to be (1.76 ± 0.02) × 10^-11 s s^-1, which translate to a dipolar magnetic field strength of 3.8 × 10¹⁴ G and characteristic age of ~7200 yr for the magnetar. It has a double-peaked pulse profile, with one broad and one narrow peak, in both soft (0.3-1.3 keV) and hard (1.3-8 keV) energy bands. The pulse fractions in the two energy bands are found to be consistent with constant values. These results are in agreement with previously published results for this source. Although two-component models produce acceptable fits to its energy spectra, single component models are much simpler and are able to explain the similarity of the pulse profiles in the low- and high-energy bands. We attempt fitting with four different single-component models and find that the best fit to the spectra is obtained by fitting a thermal Comptonization model with the photon index (Γ) between 2.0 and 2.7, and the electron temperature ( kT_e) between 0.5 and 0.9 keV, for a seed blackbody photon distribution of 0.2 keV. Finally, we conclude by discussing our results briefly.