A Systematic Study of the Thermal and Nonthermal Emission in the Supernova Remnant RCW 86 with Suzaku

Abstract

Diffusive shock acceleration by the shockwaves in supernova remnants (SNRs) is widely accepted as the dominant source for Galactic cosmic rays. However, it is unknown what determines the maximum energy of accelerated particles. The surrounding environment could be one of the key parameters. The SNR RCW 86 shows both thermal and non-thermal X-ray emission with different spatial morphologies. These emission originate from the shock-heated plasma and accelerated electrons respectively, and their intensities reflect their density distributions. Thus, the remnant provides a suitable laboratory to test possible association between the acceleration efficiency and the environment. In this paper, we present results of spatially resolved spectroscopy of the entire remnant with Suzaku. The spacially-resolved spectra are well reproduced with a combination of a power-law for synchrotron emission and a two-component optically thin thermal plasma, corresponding to the shocked interstellar medium (ISM) with kT of 0.3-0.6 keV and Fe-dominated ejecta. It is discovered that the photon index of the nonthermal component becomes smaller with decreasing the emission measure of the shocked ISM, where the shock speed has remained high. This result implies that the maximum energy of accelerated electrons in RCW 86 is higher in the low-density and higher shock speed regions.

14 pages, 15 figures, ApJ accepted

References in corpus (5)

• Detection of the Characteristic Pion-Decay Signature in Supernova Remnants
• The many sides of RCW 86: a type Ia supernova remnant evolving in its progenitor's wind bubble
• On cosmic-ray production efficiency at supernova remnant shocks propagating into realistic diffuse interstellar medium
• Aspect angle for interstellar magnetic field in SN 1006
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• The Exceptional X-ray Evolution of SN1996cr in High Resolution
• An XMM-Newton Study of the Mixed-Morphology Supernova Remnant G346.6-0.2
• Particle acceleration controlled by ambient density in the southwestern rim of RCW 86
• X-ray Line Diagnostics of Ion Temperature at Cosmic-Ray Accelerating Collisionless Shocks
• Radiative transfer of hydrogen lines from supernova remnant shock waves: contributions of 2s-state hydrogen atoms
• A new wideband radio polarization observation of the Supernova Remnant G315.4$-$2.3
• Magnetic-field Order in the Southwestern Rim of RCW 86 Constrained Using X-Ray Polarimetry