摘要
The optical spectrum of SDSS J022119.84 + 005628.4 (R. A. = 02h 21m 19.84s, Dec = 00°56' 28.4', J2000; z = 0.399785 ± 0.000558) is analyzed by multi-component profile modelling. The small flux ratio of [OⅢ]NC/Hβ (=0.78) and FWHM(HβBC) = 1778.1 ±85.9 km s-1 led us to identify SDSS J022119.84 + 005628.4 as a Narrow-line Seyfert 1 galaxy with RFe= 1.4-1.0+1.0 and intermediate radio loudness, logR = 1.93. The continuum low jump at the Balmer limit might be contributed by a starburst component, which suggests that the object is a relatively young AGN with star-formation activity in its inner region. This provides a useful observational test of the AGN evolution. The low flux ratio of the narrow components, [OⅢ]/Hβ = 1.62, and the prominent [OⅡ]γ3727 emission, [OⅡ]/[OⅢ] = 2.24, suggests that there should be a group of AGNs different from Seyfert 2s when their broad line regions are obscured by the torus on the line of sight. A possible orientation effect is suggested to interpret the observed Seyfert 1.5s-like spectrum of the object. The spectrum features prominent broad blue wings of both [OⅢ]γγ4959 and 5007. After excluding other possible contributions, we conclude that the broad components are emitted by [O Ⅲ] itself. The material emitting the broad [O III] line is probably situated in a transient line region (with a low electron density, ne < 107cm-3) between the broad line region (BLR) and the narrow line region (NLR). The object can be classified as a 'blue outlier' defined by Zamanov et al., according to its velocity shift vr([OⅢ]) = -293.6 ± 18.0 km s-1, relative to the systematic velocity.
The optical spectrum of SDSS J022119.84 + 005628.4 (R. A. = 02h 21m 19.84s, Dec = 00°56' 28.4', J2000; z = 0.399785 ± 0.000558) is analyzed by multi-component profile modelling. The small flux ratio of [OⅢ]NC/Hβ (=0.78) and FWHM(HβBC) = 1778.1 ±85.9 km s-1 led us to identify SDSS J022119.84 + 005628.4 as a Narrow-line Seyfert 1 galaxy with RFe= 1.4-1.0+1.0 and intermediate radio loudness, logR = 1.93. The continuum low jump at the Balmer limit might be contributed by a starburst component, which suggests that the object is a relatively young AGN with star-formation activity in its inner region. This provides a useful observational test of the AGN evolution. The low flux ratio of the narrow components, [OⅢ]/Hβ = 1.62, and the prominent [OⅡ]γ3727 emission, [OⅡ]/[OⅢ] = 2.24, suggests that there should be a group of AGNs different from Seyfert 2s when their broad line regions are obscured by the torus on the line of sight. A possible orientation effect is suggested to interpret the observed Seyfert 1.5s-like spectrum of the object. The spectrum features prominent broad blue wings of both [OⅢ]γγ4959 and 5007. After excluding other possible contributions, we conclude that the broad components are emitted by [O Ⅲ] itself. The material emitting the broad [O III] line is probably situated in a transient line region (with a low electron density, ne < 107cm-3) between the broad line region (BLR) and the narrow line region (NLR). The object can be classified as a 'blue outlier' defined by Zamanov et al., according to its velocity shift vr([OⅢ]) = -293.6 ± 18.0 km s-1, relative to the systematic velocity.
基金
Supported by the National Natural Science Foundation of China.
