Nonthermal x-rays from supernova remnant g330.2+1.0 and the characteristics of its central compact object

We present results from our X-ray data analysis of the supernova remnant (SNR)G330.2+1.0 and its central compact object (CCO), CXOU J160103.1-513353 (J1601 hereafter). Using our XMM-Newton and Chandra observations, we find that the X-ray spectrum of J1601 can be described by neutron star atmosphere models (T ∞ ∼ 2.5-5.5MK). Assuming the distance of d ∼ 5 kpc for J1601 as estimated for SNR G330.2+1.0, a small emission region of R ∼ 0.4-2 km is implied. X-ray pulsations previously suggested by Chandra are not confirmed by the XMM-Newton data, and are likely not real. However, our timing analysis of the XMM-Newton data is limited by poor photon statistics, and thus pulsations with a relatively low amplitude (i.e., an intrinsic pulsed fraction less than 40%) cannot be ruled out. Our results indicate that J1601 is a CCO similar to that in the Cassiopeia A SNR. X-ray emission from SNR G330.2+1.0 is dominated by power-law continuum (Γ ∼ 2.1-2.5) which primarily originates from thin filaments along the boundary shell. This X-ray spectrum implies synchrotron radiation from shock-accelerated electrons with an exponential roll-off frequency ?_rolloff ∼ 2-3 × 10¹⁷ Hz. For the measured widths of the X-ray filaments (D ∼ 0.3 pc) and the estimated shock velocity (v_s ∼ a few × 10³ km s^-1), a downstream magnetic field B ∼ 10-50 μ G is derived. The estimated maximum electron energy E_max ∼ 27-38 TeV suggests that G330.2+1.0 is a candidate TeV γ -ray source. We detect faint thermal X-ray emission in G330.2+1.0. We estimate a low preshock density n₀ ∼ 0.1 cm^-3, which suggests a dominant contribution from an inverse Compton mechanism (than the proton-proton collision) to the prospective γ -ray emission. Follow-up deep radio, X-ray, and γ -ray observations will be essential to reveal the details of the shock parameters and the nature of particle accelerations in this SNR.