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 ∼ 20 000–40 000 s . Rapid variability events have also been observed from RX J1334.2+3759. The most extreme variable event has ΔL/Δt=(1.95±1.02)×10 42  erg s −2 corresponding to a change in the intensity by a factor of ∼4 within ≲400 s. 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 ∼3.3×10 20  cm −2 ) over and above that caused by our own Galaxy (N H =7.9×10 19  cm −2 ) . The intrinsic soft X‐ray luminosity of RX J1334.2+3759 is estimated to be ∼ 2.2×10 44  erg s −1 in the energy band of 0.1–2.0 keV . The optical spectrum of RX J1334.2+3759 is typical of the narrow‐line Seyfert 1 (NLS1) galaxies showing strong Balmer H β , H α , and forbidden line of [O  iii ] λ 5007. Fe  ii multiplets, usually present in the optical spectra of NLS1 galaxies, are also detected from RX J1334.2+3759. Decomposition of the H β and H α line profiles shows the presence of narrow [full width at half‐maximum (FWHM)∼880 km s −1 ] and broad (FWHM ∼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 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.