The Extreme SED of the Quasar [HB89] 0102–272.

We have studied the spectral energy distribution of the quasar [HB89] 0102–272. The available multiwavelength data in the observers frame are one optical spectrum between 3000 and 8000 Å, 7 HST FOS spectra between 1600 and 2300 Å, and 3 ROSAT PSPC pointed observations in the 0.1–2.4 keV energy band. The αox value obtained from the HST FOS spectra and the optical spectrum is extreme with -2.2 and -2.1, respectively and is one of the steepest values reported so far. The 2500 Å luminosity density is about 5 orders of magnitude larger than the 2 keV flux density. The object is as bright as the brightest SDSS quasars but X-ray weak at 2 keV. We compare our αox findings with the mean quasar SED from [14] and conclude that [HB89] 0102–292 is unusual for any type of quasar SED’s. In addition an extreme steep soft X-ray photon index of Γ = (6.0±1.3) has been detected, the steepest value reported so far. When fitting the X-ray and optical and HST UV data simultaneously with a simple black body model an extreme discrepancy becomes apparent. While the rest frame UV photons appear to be emitted from an accretion disc, the X-ray’s must arise from something else and are not related to the UV photons. [ABSTRACT FROM AUTHOR]