We report on a broadband study of a complex X-ray source ( 1SAX J0618.0+2227 ) associated with the interaction site of the supernova remnant ( SNR ) IC 443 and ambient molecular cloud ( MC ) using NuSTAR , XMM-Newton , and Chandra observations .
Its X-ray spectrum is composed of both thermal and non-thermal components .
The thermal component can be equally well represented by either a thin plasma model with kT = 0.19 keV or a blackbody model with kT = 0.11 keV .
The non-thermal component can be fit with either a power-law with \Gamma \sim 1.7 or a cutoff power-law with \Gamma \sim 1.5 and a cutoff energy at E _ { cut } \sim 18 keV .
Using the newly obtained NuSTAR dataset , we test three possible scenarios for isolated X-ray sources in the SNR-MC interaction site : 1 ) pulsar wind nebula ( PWN ) ; 2 ) SNR ejecta fragment ; 3 ) shocked molecular clump .
We conclude that this source is most likely composed of a SNR ejecta ( or a PWN ) and surrounding shocked molecular clumps .
The nature of this hard X-ray source in the SNR-MC interaction site of IC 443 may shed light on unidentified X-ray sources with hard X-ray spectra in rich environments for star forming regions , such as the Galactic center .