Chandra Observations of Galactic Supernova Remnant Vela Jr.: A New Sample of Thin Filaments Emitting Synchrotron X-Rays

The Galactic supernova remnant (SNR) Vela Jr. (RX J0852.0-4622, G266.6-1.2) shows sharp filamentary structures on its northwestern edge in the hard X-ray band. The filaments are very smooth and located on the extreme outside edge of the remnant. We measured the averaged scale width of the filaments (w_u and w_d) with excellent spatial resolution with Chandra, and they are on the order of the size of the point-spread function of Chandra on the upstream side and 49.5" (36.0"-88.8") on the downstream side. The spectra of the filaments are very hard and have no linelike structure; they were well reproduced with an absorbed power-law model with Γ=2.67 (2.55-2.77) or a SRCUT model with ν_roll=4.3 (3.4-5.3)×10¹⁶ Hz under the assumption of p=0.3. These results imply that the hard X-rays are synchrotron radiation emitted by accelerated electrons, as mentioned previously. Using a correlation between the function B≡ν_roll/w²_d and the SNR age, we estimated the distance and the age of Vela Jr.: the estimated distance and age are 0.33 (0.26-0.50) kpc and 660 (420-1400) yr, respectively. These results are consistent with previous reports, implying that the B-age relation may be a useful tool for estimating the distance and the age of synchrotron X-ray-emitting SNRs.