Open AccessChandra measurements of the X‐ray core and cluster of 3C 220.1
Author(s) -
Worrall D.M.,
Birkinshaw M.,
Hardcastle M.J.,
Lawrence C.R.
Publication year - 2001
Publication title -
monthly notices of the royal astronomical society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.058
H-Index - 383
eISSN - 1365-2966
pISSN - 0035-8711
DOI - 10.1046/j.1365-8711.2001.04644.x
Subject(s) - physics , astrophysics , cooling flow , radius , luminosity , quasar , spectral index , active galactic nucleus , radio galaxy , galaxy cluster , cluster (spacecraft) , point source , galaxy , astronomy , spectral line , optics , computer science , programming language , computer security
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 separates into cluster gas of emission‐weighted kT∼5 keV , 0.7–12 keV luminosity (to a radius of 45 arcsec) of 5.6×10 44 erg s −1 and unresolved emission (coincident with the radio core). While the extended X‐ray emission 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 properties of the gas suggest a massive cooling flow of ∼130 M ⊙ yr −1 , and the data show weak evidence for a temperature gradient. The central unresolved X‐ray emission has a power‐law spectral energy index α∼0.7 and 0.7–12 keV luminosity of 10 45 erg s −1 , and any intrinsic absorption is relatively small. The two‐point spectrum of the core emission between radio and X‐ray energies has α rx =0.75 . Since this is a flatter spectrum than seen in other sources where the X‐ray emission is presumed 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 to be the case for lobe‐dominated quasars. Simple unification models would be challenged if this were found to be the case for a large fraction of high‐power radio galaxies.