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 J1334.2+3759 with a steep soft X-ray spectrum. Soft X-ray emission from the NLQSO is highly variable. Changes in the intensity by a factor of ~2 have been detected in the ROSAT Position Sensitive Proportional Counter (PSPC) observations of RX J1334.2+3759 on time-scales of ~20000-40000s. Rapid variability events have also been observed from RX J1334.2+3759. The most extreme variable event has ΔL/Δt=(1.95+/-1.02)×10⁴²ergs^-2 corresponding to a change in the intensity by a factor of ~4 within <~400s. The PSPC spectra of the NLQSO can be well represented by a power law of photon index Γ_X~3.8, modified by an absorbing column local to the source (ΔN_H~3.3×10²⁰cm^-2) over and above that caused by our own Galaxy (N_H=7.9×10¹⁹cm^-2). The intrinsic soft X-ray luminosity of RX J1334.2+3759 is estimated to be ~2.2×10⁴⁴ergs^-1 in the energy band of 0.1-2.0keV. The optical spectrum of RX J1334.2+3759 is typical of the narrow-line Seyfert 1 (NLS1) galaxies showing strong Balmer Hβ, Hα, and forbidden line of [Oiii]λ5007. Feii multiplets, usually present in the optical spectra of NLS1 galaxies, are also detected from RX J1334.2+3759. Decomposition of the Hβ and Hα line profiles shows the presence of narrow [full width at half-maximum (FWHM)~880kms^-1] and broad (FWHM~2850kms^-1) components in the spectrum of RX J1334.2+3759. The narrow-line region of RX J1334.2+3759 appears to be significantly different from those of normal Seyfert galaxies. A possible explanation for the observed properties of the narrow-line region and the broad-line region is suggested in terms of density enhancements.