An optical and X-ray study of the peculiar narrow-line quasar QSO 0117-2837

Abstract

We present an optical and X-ray study of the quasar QSO 0117-2837. It exhibits an interesting combination of optical and X-ray properties: Despite its extremely steep observed X-ray spectrum (Gamma_x ~ -4 when fit by a simple powerlaw), its Balmer lines are fairly broad. A two-component Gaussian fit to H_beta yields FWHM_{Hbeta, broad} ~ 4000 km/s, and places QSO 0117-2837 in the `zone of avoidance' in the FWHM_{Hbeta}-Gamma_x diagram. A time variability analysis shows that QSO 0117-2837 is another case of Narrow-line Sy1 galaxy (NLSy1 hereafter) which does not show any X-ray variability during the observation. The results are discussed in view of the NLSy1 character of QSO 0117-2837.