SIMBAD references

We have detected an emission-line feature at 4 keV in the X-ray emission from a sky region including the distant radio galaxy 3C 220.1 (z=0.62) obtained with ASCA. The line energy is 6.1-7.0 keV (90% confidence) in the rest frame of 3C 220.1. Within the present statistics, the observed spectra are consistent with two different models: a nonthermal model consisting of a power-law continuum plus a 6.4 keV iron emission line and a Raymond-Smith thin thermal emission model of kT∼6 keV with a metal abundance of ∼0.5 solar. However, because of the large (∼500 eV) equivalent width of the line, a significant fraction of the X-ray emission is likely to arise from the hot intracluster gas associated with the galaxy cluster that includes 3C 220.1. The spectral parameters of the thermal emission are consistent with the luminosity-temperature relation of nearby clusters.