XMM-Newton study of hard X-ray sources in IC 443

Abstract

We present XMM-Newton observations of hard X-ray emission from the field of IC 443, a supernova remnant interacting with a molecular cloud. The hard emission from the field is dominated by 12 isolated sources having 2-10 keV flux ≳10-14 erg cm-2 s-1. Only a fraction of the sources are expected to be extragalactic or stars on statistical grounds, while the others may be associated with the remnant. We have analyzed near-infrared K band and also DSS optical data for all of the detected sources, finding that six X-ray sources are located in a relatively small 15′ × 15′ region where there is strong 2.2 μm infrared emission, indicating interaction with a molecular cloud. The source 1SAX J0618.0+2227, the brightest in this region (excluding the plerion), is resolved with XMM-Newton into two sources, one of which is extended and has a hard power law spectrum photon index ≲1.5) and shows some indications of spectral line signatures (e.g. Si), while the other is point-like and has a featureless spectrum of steeper photon index ∼2.2. Possible interpretations of some of the discrete sources in terms of interaction between the SNR and the molecular cloud are discussed.