2021ApJ...919..123S -
Astrophys. J., 919, 123-123 (2021/October-1)
ALMA CO observations of the mixed-morphology supernova remnant W49B: efficient production of recombining plasma and hadronic gamma rays via shock-cloud interactions.
SANO H., YOSHIIKE S., YAMANE Y., HAYASHI K., ENOKIYA R., TOKUDA K., TACHIHARA K., ROWELL G., FILIPOVIC M.D. and FUKUI Y.
Abstract (from CDS):
We carried out new CO(J = 2-1) observations toward the mixed-morphology supernova remnant (SNR) W49B with the Atacama Large Millimeter/submillimeter Array. We found that CO clouds at ∼10 km s–1 show a good spatial correspondence to the synchrotron radio continuum as well as to an X-ray deformed shell. The bulk mass of molecular clouds accounts for the western part of the shell, not the eastern shell, where near-infrared H2 emission is detected. The molecular clouds at ∼10 km s–1 show higher kinetic temperatures of ∼20-60 K, suggesting that modest shock heating occurred. The expanding motion of the clouds with ΔV ∼ 6 km s–1 was formed by strong winds from the progenitor system. We argue that the barrel-like structure of Fe-rich ejecta was possibly formed not only by an asymmetric explosion, but also by interactions with dense molecular clouds. We also found a negative correlation between the CO intensity and the electron temperature of recombining plasma, implying that the origin of the high-temperature recombining plasma in W49B can be understood to be the thermal conduction model. The total energy of accelerated cosmic-ray protons Wp is estimated to be ∼2 x 1049 erg by adopting an averaged gas density of ∼650 ± 200 cm–3. The SNR age-Wp diagram indicates that W49B shows one of the highest in situ values of Wp among gamma-ray-bright SNRs.
Abstract Copyright:
© 2021. The American Astronomical Society. All rights reserved.
Journal keyword(s):
Supernova remnants - Interstellar medium - Cosmic ray sources - Gamma-ray sources - X-ray sources
Simbad objects:
33
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