CXOU J160103.1-513353: another central compact object with a carbon atmosphere?

Abstract

We report on the analysis of XMM-Newton observations of the central compact object CXOU J160103.1-513353 located in the center of the non-thermally emitting supernova remnant (SNR) G330.2+1.0. The X-ray spectrum of the source is well described with either single-component carbon or two-component hydrogen atmosphere models. In the latter case, the observed spectrum is dominated by the emission from a hot component with a temperature ∼3.9 MK, corresponding to the emission from a hotspot occupying ∼1% of the stellar surface (assuming a neutron star with mass M = 1.5 M_⊙, radius of 12 km, and distance of ∼5 kpc as determined for the SNR). The statistics of the spectra and obtained upper limits on the pulsation amplitude expected for a rotating neutron star with hot spots do not allow us to unambiguously distinguish between these two scenarios. We discuss, however, that while the non-detection of the pulsations can be explained by the unfortunate orientation in CXOU J160103.1-513353, this is not the case when the entire sample of similar objects is considered. We therefore conclude that the carbon atmosphere scenario is more plausible.