Spatially-Resolved Study of Recombining Plasma in W49B Using XMM-Newton

Abstract

W49B is the youngest SNR to date that exhibits recombining plasma. The two prevailing theories of this overionization are rapid cooling via adiabatic expansion or through thermal conduction with an adjacent cooler medium. To constrain the origin of the recombining plasma in W49B, we perform a spatially-resolved spectroscopic study of deep XMM-Newton data across 46 regions. We adopt a 3-component model (with one ISM and two ejecta components), and we find that recombining plasma is present throughout the entire SNR, with increasing overionization from east to west. The latter result is consistent with previous studies, and we attribute the overionization in the west to adiabatic expansion. However, our findings contrast these prior works as we find evidence of overionization in the east as well. As the SNR is interacting with molecular material there, we investigate the plausibility of thermal conduction as the origin of the rapid cooling. We show that based on the estimated timescales, it is possible that small-scale thermal conduction through evaporation of clumpy, dense clouds with a scale of 0.1-1.0 pc can explain the observed overionization in the east.

19 pages, 8 figures, 2 tables, submitted to ApJ

References in corpus (9)

• A Near-Infrared and X-ray Study of W49B: A Wind Cavity Explosion
• Supernova remnant W49B and its environment
• Non-equilibrium ionization in mixed-morphology supernova remnants
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• An XMM-Newton study of the mixed-morphology supernova remnant W28 (G6.4-0.1)
• Progenitors of Recombining Supernova Remnants
• Localized Recombining Plasma in G166.0+4.3: A Supernova Remnant with an Unusual Morphology
• An XMM-Newton Study of the Mixed-Morphology Supernova Remnant G346.6-0.2
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Cited by in corpus (4)

• ALMA CO Observations of the Mixed-Morphology Supernova Remnant W49B: Efficient Production of Recombining Plasma and Hadronic Gamma-rays via Shock-Cloud Interactions
• Unusually high HCO+/CO ratios in and outside supernova remnant W49B
• Initial state of the recombining plasma in supernova remnant W 28
• Investigation of the Physical Origin of Overionized Recombining Plasma in the Supernova Remnant IC 443 with XMM-Newton