The European Large Area ISO Survey - VI. Discovery of a new hyperluminous infrared galaxy

We report the discovery of the first hyperluminous infrared galaxy (HyLIG) in the course of the European Large Area ISO Survey (ELAIS). This object ha s been detected by ISO at 6.7, 15 and 90 mum, and is found to be a broad-li ne, radio-quiet quasar at a redshift z=1.099. From a detailed multicomponen t model fit of the spectral energy distribution, we derive a total IR lumin osity L-IR (1-1000 mum) approximate to 1.0 x 10(13) h(65)(-2) L-circle dot (q(0) = 0.5), and discuss the possible existence of a starburst contributin g to the far-IR output. Observations to date present no evidence for lens m agnification. This galaxy is one of the very few HyLIGs with a X-ray detect ion. On the basis of its soft X-ray properties, we suggest that this broad- line object may be the face-on analogue of narrow-line, Seyfert-like HyLIGs .