The loss-limited electron energy in SN 1006: effects of the shock velocity and of the diffusion process

TL;DR

This study confirms that radiative losses shape the high-energy electron spectrum in SN 1006, showing that shock velocity and diffusion processes influence the synchrotron cutoff energy, with electrons accelerating near the Bohm limit.

Contribution

The paper demonstrates that the loss-limited model explains the spectral variations in SN 1006 and links the cutoff energy to shock velocity and diffusion conditions.

Findings

Maximum cutoff energy correlates with highest shock speeds.

Electron acceleration occurs near the Bohm diffusion limit.

Variations in cutoff energy in thermal limbs are explored.

Abstract

The spectral shape of the synchrotron X-ray emission from SN 1006 reveals the fundamental role played by radiative losses in shaping the high-energy tail of the electron spectrum. We analyze data from the XMM-Newton SN 1006 Large Program and confirm that in both nonthermal limbs the loss-limited model correctly describes the observed spectra. We study the physical origin of the observed variations of the synchrotron cutoff energy across the shell. We investigate the role played by the shock velocity and by the electron gyrofactor. We found that the cutoff energy of the syncrotron X-ray emission reaches its maximum value in regions where the shock has experienced its highest average speed. This result is consistent with the loss-limited framework. We also find that the electron acceleration in both nonthermal limbs of SN 1006 proceeds close to the Bohm diffusion limit, the gyrofactor being in the range 1.5-4. We finally investigate possible explanations for the low values of cutoff energy measured in thermal limbs.