Toward the Understanding of the Physical Origin of Recombining Plasma in the Supernova Remnant IC 443

Abstract

We perform a spatially resolved spectroscopic analysis of X-ray emission from the supernova remnant (SNR) IC 443 with Suzaku. All the spectra are well reproduced by a model consisting of a collisional ionization equilibrium (CIE) and two recombining plasma (RP) components. Although previous X-ray studies found an RP in the northeastern region, this is the first report on RPs in the other parts of the remnant. The electron temperature $k{T}_e$ of the CIE component is almost uniform at $\sim 0.2$ keV across the remnant. The CIE plasma has metal abundances consistent with solar and is concentrated toward the rim of the remnant, suggesting that it is of shocked interstellar medium origin. The two RP components have different $k{T}_e$: one in the range of 0.16$-$0.28 keV and the other in the range of 0.48$-$0.67 keV. The electron temperatures of both RP components decrease toward the southeast, where the SNR shock is known to be interacting with a molecular cloud. We also find the normalization ratio of the lower-$k{T}_e$ RP to higher-$k{T}_e$ RP components increases toward the southeast. Both results suggest the X-ray emitting plasma in the southeastern region is significantly cooled by some mechanism. One of the plausible cooling mechanisms is thermal conduction between the hot plasma and the molecular cloud. If the cooling proceeds faster than the recombination timescale of the plasma, the same mechanism can account for the recombining plasma as well.

15 pages, 10 figures, 6 tables. Accepted for publication in ApJ on 16 Nov 2017

References in corpus (4)

• XMM-Newton observations of the supernova remnant IC443: I. soft X-ray emission from shocked interstellar medium
• On the metal abundances inside mixed-morphology supernova remnants: the case of IC443 and G166.0+4.3
• Localized Recombining Plasma in G166.0+4.3: A Supernova Remnant with an Unusual Morphology
• Discovery of Enhanced Radiative Recombination Continua of He-like Iron and Calcium from IC 443 and Its Implications

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• Spatially Resolved Chandra Spectroscopy of the Large Magellanic Cloud Supernova Remnant N132D
• New Scenario of plasma evolution in IC 443
• QUIJOTE scientific results -- V. The microwave intensity and polarisation spectra of the Galactic regions W49, W51 and IC443
• G189.6+03.3: the first complete X-ray view provided by SRG/eROSITA
• Discovery of recombining plasma associated with the candidate supernova remnant G189.6+3.3 with Suzaku
• On the formation of over-ionized plasma in evolved supernova remnants