Chandra discovery of the intracluster medium around UM425 at redshift 1.47

Abstract

We report on a discovery of a candidate cluster of galaxies at redshift z=1.47 based on Chandra observations in the field of quasars UM425 A & B. We detect with high significance diffuse emission due the intracluster hot gas around the quasar pair. This is the second highest redshift cluster candidate after 3C294 at z=1.786. The diffuse emission is elliptical in shape with about 17" extent. If indeed at z=1.47, this corresponds to a physical size of 140 h_{70}^{-1} Kpc and 2--10 keV luminosity of about 3 times 10^{43} erg/s. The cluster is unlikely to be the long sought gravitational lens invoked to explain unusual brightness of UM425 A and the close quasar pair. Coexistence of the quasars with the cluster suggests a link of activity to cluster environment. The unusual brightness of UM425 A may then be due to a higher accretion rate. We also comment briefly on the X-ray spectra of UM 425 A & B which also happen to be broad absorption line quasars. We argue that present evidence suggests that the quasars are just a pair and not lensed images of the same quasar.

Submitted to ApJ Letters