One of the six extended X-ray sources found in the Chandra Deep Field North is centred on HDF 130 , which has recently been shown to be a massive galaxy at z = 1.99 with a compact radio nucleus .
The X-ray source has a roughly double-lobed structure with each lobe about 41 arcsec long , or 345 kpc at the redshift of HDF 130 .
We have analyzed the 2 Ms X-ray image and spectrum of the source and find that it is well fit by a power-law continuum of photon index 2.65 and has a 2–10 keV luminosity of 5.4 \times 10 ^ { 43 } \hbox { $ \thinspace erg \thinspace s ^ { -1 } $ } ( if at z = 1.99 ) .
Any further extended emission within a radius of 60 arcsec has a luminosity less than half this value , which is contrary to what is expected from a cluster of galaxies .
The source is best explained as an inverse Compton ghost of a giant radio source , which is no longer being powered , and for which Compton losses have downgraded the energetic electrons , \gamma > 10 ^ { 4 } , required for high-frequency radio emission .
The lower energy electrons , \gamma \sim 1000 , produce X-rays by inverse Compton scattering on the Cosmic Microwave Background .
Depending on the magnetic field strength , some low frequency radio emission may remain .
Further inverse Compton ghosts may exist in the Chandra deep fields and beyond .