Optical and X-ray characteristics of a newly discovered narrow-line quasi-stellar object: RX J1334.2+3759

We report the discovery of a narrow-line quasi-stellar object (NLQSO) RX J1 334.2+3759 with a steep soft X-ray spectrum. Soft X-ray emission from the N LQSO is highly variable. Changes in the intensity by a factor of similar to 2 have been detected in the ROSAT Position Sensitive Proportional Counter ( PSPQ observations of RX J1334.2+3759 on time-scales of similar to 20000-400 00s. Rapid variability events have also been observed from RX J1334.2 + 375 9. The most extreme variable event has DeltaL/Deltat = (1.95 +/- 1.02) x 10 (42) erg s(-2) corresponding to a change in the intensity by a factor of si milar to4 within less than or similar to 400 s. The PSPC spectra of the NLQ SO can be well represented by a power law of photon index Gamma (x) similar to 3.8, modified by an absorbing column local to the source (DeltaN(H) sim ilar to 3.3 X 10(20) cm(-2)) over and above that caused by our own Galaxy ( NH = 7.9 X 10(19) cm(-2)). The intrinsic soft X-ray luminosity of RX J1334. 2+3759 is estimated to be similar to2.2 x 10(44) erg s(-1) in the energy ba nd of 0.1-2.0 keV. The optical spectrum of RX J1334.2+3759 is typical of th e narrow-line Seyfert 1 (NLSI) galaxies showing strong Balmer H beta, H alp ha, and forbidden line of [O III]lambda 5007. Fe it multiplets, usually pre sent in the optical spectra of NLSI galaxies, are also detected from RX J13 34.2+3759. Decomposition of the Ho and Ha line profiles shows the presence of narrow [full width at half-maximum (FWHM) similar to 880 km s(-1)] and b road (FWHM similar to 2850 km s(-1)) components in the spectrum of RX J1334 .2+3759. The narrow-line region of RX J1334.2 + 3759 appears to be signific antly different from those of normal Seyfert galaxies. A possible explanati on for the observed properties of the narrow-line region and the broad-line region is suggested in terms of density enhancements.