Nonthermal emission properties of the northwestern rim of supernova remnant RX J0852.0-4622
Abstract
The supernova remnant (SNR) RX J0852.0-4622 (Vela Jr., G266.6-1.2) is one of the most important SNRs for investigating the acceleration of multi-TeV particles and the origin of Galactic cosmic rays because of its strong synchrotron X-ray and TeV γ-ray emission, which show a shell-like morphology similar to each other. Using the XMM-Newton archival data consisting of multiple pointing observations of the northwestern rim of the remnant, we investigate the spatial properties of the nonthermal X-ray emission as a function of distance from an outer shock wave. All X-ray spectra are well reproduced by an absorbed power-law model above 2 keV. It is found that the spectra show gradual softening from a photon index Γ = 2.56 in the rim region to Γ = 2.96 in the interior region. We show that this radial profile can be interpreted as a gradual decrease of the cutoff energy of the electron spectrum due to synchrotron cooling. By using a simple spectral evolution model that includes continuous synchrotron losses, the spectral softening can be reproduced with the magnetic field strength in the post-shock flow to less than several tens of μG. If this is a typical magnetic field in the SNR shell, γ-ray emission would be accounted for by inverse Compton scattering of high-energy electrons that also produce the synchrotron X-ray emission. Future hard X-ray imaging observations with Nustar and ASTRO-H and TeV γ-ray observations with the Cherenkov Telescope Array (CTA) will allow us to explore other possible explanations of the systematic softening of the X-ray spectra.
- Publication:
-
Astronomy and Astrophysics
- Pub Date:
- March 2013
- DOI:
- 10.1051/0004-6361/201220525
- arXiv:
- arXiv:1302.0193
- Bibcode:
- 2013A&A...551A.132K
- Keywords:
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- radiation mechanisms: non-thermal;
- ISM: supernova remnants;
- X-rays: ISM;
- Astrophysics - High Energy Astrophysical Phenomena
- E-Print:
- accepted by A&