Emission lines from the broad emission line region(BELR) and the narrow emission line region(NELR) of active galactic nuclei(AGNs) have been extensively studied. However, emission lines are rarely detected between these two regions. We present a detailed analysis of quasar SDSS J232444.80–094600.3(SDSS J2324-0946), which is remarkable for its strong intermediate-width emission lines(IELs) with FWHM≈1800 km s^(-1). The IEL component is present in different emission lines, including the permitted lines Lyαλ1216, C IV λ1549, semiforbidden line C III] λ1909, and forbidden lines [O III] λλ4959, 5007.With the aid of photo-ionization models, we found that the IELs are produced by gas with a hydrogen density of nH～10^(6.2)-10^(6.3)cm^(-3), a distance from the central ionizing source of Ra dust-to-gas ratio of～35-50 pc, a covering factor of～6%, and ≤4% that of the SMC. We suggest that the strong IELs of this quasar are produced by nearly dust-free and intermediate-density gas located at the skin of the dusty torus. Such strong IELs, which serve as a useful diagnostic, can provide an avenue to study the properties of gas between the BELR and the NELR.
Zhen-Zhen LiHong-Yan ZhouLei HaoShu-Fen WangTuo JiBo Liu
In this report,we find the MBH estimated from the formalism of Wang et al.are more consistent with those from the MBH-σ relation than those from previous single-epoch mass estimators,using a large sample of AGNs.Furthermore,we examine the diferences between the line widths of Hβ and Mg Ⅱ in detail by comparing their line profiles.The flux around the line core and that in the wing of both Hβ and Mg Ⅱ show an opposite variation tendency,which indicates the BLR is multi-componential.The contribution of the wing makes the FWHM deviate fromσline,and thus bias the MBH estimated from previous single-epoch mass estimators.Thus the correction on the formalism suggested by Wang et al.is crucial to MBH estimation.
We report the discovery of a broad absorption line (BAL) of ～ 104 km s-1 in width in the previously known BL Lac object PKS 0138-097, which we tentatively identified as an Mg II BAL. This is the first detection of a BAL, which is sometimes seen in powerful quasars with high accretion rates, in a BL Lac object. The BAL was clearly detected in its spectra spanning two epochs at a high luminosity state taken in the Sloan Digital Sky Survey (SDSS), while it disappeared in three SDSS spectra taken at a low luminosity state. The BAL and its variability pattern were also found in its historical multi-epoch spectra in the literature, but have been overlooked previously. In its high resolution radio maps, PKS 0138-097 shows a core plus a onesided parsec-scale jet. The BAL variability can be interpreted as follows: The optical emission is dominated by the core in a high state and by the jet in a low state and the BAL material is located between the core and jet so that the BAL appears only when the core is shining. Our discovery suggests that outflows may also be produced in active galactic nuclei at a low accreting state.
We report the discovery of Balmer broad absorption lines (BALs) in the quasar LBQS 1206+1052 and present a detailed analysis of the peculiar absorption line spectrum. Besides the Mg II λλ2796, 2803 doublet, BALs are also detected in the He I* multiplet at λλ2946, 3189, 3889 A arising from the metastable helium 2 3 S level, and in Hα and Hβ from the excited hydrogen H I* n = 2 level, which are rarely seen in quasar spectra. We identify two components in the BAL troughs of v ～ 2000 km s 1 width: One component shows an identical profile in H I*, He I* and Mg II with its centroid blueshifted by v c ≈ 726 km s-1 . The other component is detected in He I* and Mg II with v c ≈ 1412 km s-1 . We estimate the column densities of H I*, He I*, and Mg II, and compare them with possible level population mechanisms. Our results favor the scenario that the Balmer BALs originate in a partially ionized region with a column density of N H ～ 10 21 10 22 cm-2 for an electron density of n e ～ 10 6 10 8 cm-3 via Lyα resonant scattering pumping. The harsh conditions needed may help to explain the rarity of Balmer absorption line systems in quasar spectra. With an i-band PSF magnitude of 16.50, LBQS 1206+1052 is the brightest Balmer-BAL quasar ever reported. Its high brightness and unique spectral properties make LBQS 1206+1052 a promising candidate for followup high-resolution spectroscopy, multi-band observations, and long-term monitoring.
