Discovery of a jet-like structure with overionized plasma in the SNR IC443

TL;DR

This paper reports the discovery of a jet-like, overionized plasma structure in the supernova remnant IC443, providing insights into its plasma properties, the PWN relationship, and the nature of ejecta in core-collapse supernovae.

Contribution

It presents the first observation of an overionized, jet-like ejecta structure in IC443, linking it to the PWN and expanding understanding of collimated ejecta in supernova remnants.

Findings

Identified a Mg-rich, overionized jet in IC443.

The jet aligns with the PWN, suggesting a connection.

First detection of overionized plasma in a jet-like ejecta in IC443.

Abstract

IC443 is a supernova remnant located in a quite complex environment since it interacts with nearby clouds. Indications for the presence of overionized plasma have been found though the possible physical causes of overionization are still debated. Moreover, because of its peculiar position and proper motion, it is not clear if the pulsar wind nebula (PWN) within the remnant is the relic of the IC443 progenitor star or just a rambling one seen in projection on the remnant. Here we address the study of IC443 plasma in order to clarify the relationship PWN-remnant, the presence of overionization and the origin of the latter. We analyzed two \emph{XMM-Newton} observations producing background-subtracted, vignetting-corrected and mosaicked images in two different energy bands and we performed a spatially resolved spectral analysis of the X-ray emission. We identified an elongated (jet-like) structure with Mg-rich plasma in overionization. The head of the jet is interacting with a molecular cloud and the jet is aligned with the position of the PWN at the instant of the supernova explosion. Interestingly, the direction of the jet of ejecta is somehow consistent with the direction of the PWN jet. Our discovery of a jet of ejecta in IC443 enlarge the sample of core-collapse SNRs with collimated ejecta structures. IC443's jet is the first one which shows overionized plasma, possibly associated with the adiabatic expansion of ejecta. The match between the jet's direction and the original position of the PWN strongly supports the association between the neutron star and IC443.