Chandra measurements of the X-ray core and cluster of 3C 220.1

We report results of an 18-ks exposure with the ACIS instrument on Chandra of the powerful z = 0.62 radio galaxy 3C 220.1. The X-ray emission separate s into cluster gas of emission-weighted kT similar to 5 keV, 0.7-12 keV lum inosity (to a radius of 45 arcsec) of 5.6 x 10(44) erg s(-1) and unresolved emission (coincident with the radio core). while the extended X-ray emissi on is clearly thermal in nature, a straightforward cooling-flow model, even in conjunction with a point-source component, is a poor fit to the radial profile of the X-ray emission. This is despite the fact that the measured p roperties of the gas suggest a massive cooling flow of similar to 130 M-. y r(-1), and the data show weak evidence for a temperature gradient. The cent ral unresolved X-ray emission has a power-law spectral energy index alpha s imilar to 0.7 and 0.7-12 keV luminosity of 10(45) erg s(-1), and any intrin sic absorption is relatively small. The two-point spectrum of the core emis sion between radio and X-ray energies has alpha (rx) = 0.75. Since this is a flatter spectrum than seen in other sources where the X-ray emission is p resumed to be radio-related, regions close to the active galactic nucleus ( AGN) in this source may dominate the central X-ray output, as is believed t o be the case for lobe-dominated quasars. Simple unification models would b e challenged if this were found to be the case for a large fraction of high -power radio galaxies.