Discovery of a z=4.93, X-ray selected quasar by the Chandra Multiwavelength Project (ChamP)
J. D. Silverman, P. J. Green, D. W. Kim, B. J. Wilkes, R. A. Cameron, D. Morris, A. Dosaj, C. Smith, L. Infante, P. S. Smith, B. T. Jannuzi, S. Mathur
Abstract
We present X-ray and optical observations of CXOMP J213945.0-234655, a high redshift (z=4.93) quasar discovered through the Chandra Multiwavelength Project (ChaMP). This object is the most distant X-ray selected quasar published, with an X-ray luminosity of L(X)=5.9x10^44 erg/s (measured in the 0.3-2.5 keV band and corrected for Galactic absorption). CXOMP J213945.0-234655 is a g' dropout object (>26.2), with r'=22.87 and i'=21.36. The rest-frame X-ray to optical flux ratio is similar to quasars at lower redshifts and slightly X-ray bright relative to z>4 optically-selected quasars observed with Chandra. The ChaMP is beginning to acquire significant numbers of high redshift quasars to investigate the unobscured X-ray luminosity function out to z~5.