First X-ray spectrum of the most luminous quasar PKS 2126-158.

Abstract

For the first time the detailed results of the spectral analysis of the X-ray (0.1-10 keV) spectrum of the luminous (z = 3.27), radio-loud quasar, PKS 2126 - 158, are presented. The spectrum of this quasar was obtained from the EXOSAT database. Power law and fixed absorption model fits well with the spectrum. The parameters of this model suggest that this quasar is a flat spectrum source (α = 0.3+/-0.15). Derived soft (0.1-2 keV) and hard (2-10 keV) X- ray luminosities of this quasar are (0.7 +/- 0.1)10^48^ erg s^-1^ and (2.3+/-0.3)10^48^ erg s^-1^ respectively. No soft excess and low energy absorption have been detected in this source. Thermal bremsstrahlung model also fits well with the spectrum of PKS 2126 - 158 and the derived rest-frame temperature is 6.4_-4_^+40^ keV. This is the most luminous quasar which has been detected in the hard X-rays (30 keV at source).