THE REFINED SHOCK VELOCITY OF THE X-RAY FILAMENTS IN THE RCW 86 NORTHEAST RIM

Journal Article · Sun Mar 20 04:00:00 EDT 2016 · Astrophysical Journal Letters

DOI:https://doi.org/10.3847/2041-8205/820/1/L3· OSTI ID:22518580

Yamaguchi, Hiroya; Castro, Daniel; Williams, Brian J.; Petre, Robert ^[1]; Katsuda, Satoru ^[2]; Lopez, Laura A. ^[3]; Slane, Patrick O.

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1. NASA Goddard Space Flight Center, Code 662, Greenbelt, MD 20771 (United States)
2. Institute of Space and Astronautical Science, JAXA, 3-1-1 Yoshinodai, Sagamihara, Kanagawa 229-8510 (Japan)
3. Department of Astronomy and Center for Cosmology and Astro-Particle Physics, The Ohio State University, Columbus, OH 43210 (United States)

A precise measurement of shock velocities is crucial for constraining the mechanism and efficiency of cosmic-ray (CR) acceleration at supernova remnant (SNR) shock fronts. The northeastern rim of the SNR RCW 86 is thought to be a particularly efficient CR acceleration site, owing to the recent result in which an extremely high shock velocity of ∼6000 km s{sup −1} was claimed. Here, we revisit the same SNR rim with the Chandra X-ray Observatory, 11 years after the first observation. This longer baseline than previously available allows us to determine a more accurate proper motion of the nonthermal X-ray filament, revealing a much lower velocity of 3000 ± 340 km s{sup −1} (and even slower at a brighter region). Although the value has dropped to one-half of that from the previous X-ray measurement, it is still higher than the mean velocity of the Hα filaments in this region (∼1200 km s{sup −1}). This discrepancy implies that the filaments bright in nonthermal X-rays and Hα emission trace different velocity components, and thus a CR pressure constrained by combining the X-ray kinematics and the Hα spectroscopy can easily be overestimated. We also measure the proper motion of the thermal X-ray filament immediately to the south of the nonthermal one. The inferred velocity (720 ± 360 km s{sup −1}) is significantly lower than that of the nonthermal filament, suggesting the presence of denser ambient material, possibly a wall formed by a wind from the progenitor, which has drastically slowed down the shock.

• OSTI ID: 22518580
• Journal Information: Astrophysical Journal Letters, Journal Name: Astrophysical Journal Letters Journal Issue: 1 Vol. 820; ISSN 2041-8205
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
ACCELERATION
COSMIC RADIATION
EFFICIENCY
EMISSION SPECTRA
FILAMENTS
HYDROGEN
PROPER MOTION
SHOCK WAVES
STELLAR WINDS
SUPERNOVA REMNANTS
VELOCITY
X RADIATION