The Fe line diagnostic of the nuclear source in the prototype ULIG Arp220

We propose a 90ks XMMNewton/EPIC observation of the UltraLuminous InfraredGalaxy Arp220,the nearest ULIG. Based on ASCA and BeppoSAX observations,if anAGN were the major evergy source in this object,it must be Comptonthick. A 50ksChandra observation has located a faint hard Xray source at one of the doublenuclei, and the spectrum hinted at the presence of an iron Kline. The primaryaim of this proposal is to obtain a high quality iron Kline spectrum with theEPIC cameras in order to determine the origin of the hard Xray emission, whichwe believe will provide the ultimate test as to whether an AGN powers theenormous infrared luminosity in this prototype ULIG, as well as have importantimplications for interpreting the Xray emission from all ULIGs. truncated!, Please see actual data for full text [truncated!, Please see actual data for full text]