TYPE 2 ACTIVE GALACTIC NUCLEI WITH DOUBLE-PEAKED [O iii] LINES: NARROW-LINE REGION KINEMATICS OR MERGING SUPERMASSIVE BLACK HOLE PAIRS?
TYPE 2 ACTIVE GALACTIC NUCLEI WITH DOUBLE-PEAKED [O iii] LINES: NARROW-LINE REGION KINEMATICS OR MERGING SUPERMASSIVE BLACK HOLE PAIRS?
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DOI：
10.1088/0004-637x/708/1/427
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发表时间：
2009-08
期刊：
影响因子：
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通讯作者：
Xin Liu;Yue Shen;M. Strauss;J. Greene
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文献类型：
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作者：
Xin Liu;Yue Shen;M. Strauss;J. Greene
我们从斯隆数字巡天第七次数据中选取了167个具有双峰[O iii] λλ 4959，5007窄发射线的2型活动星系核（AGN）。双峰分布可以很好地模拟两个速度分量，蓝移和红移的系统速度。这些天体中有一半有更突出的红移分量。在Hβ发射线较强的情况下，它还显示了两个速度分量，它们的视线（LOS）速度偏移与[O iii]中的一致。两个分量之间的相对LOS速度偏移通常为几百km s-1，比每个分量的半峰线全宽大1.5倍。偏移量与宿主恒星速度色散σ* 相关。与在红移、[O iii] λ5007等效宽度和光度上匹配的常规2型活动星系核样本相比，该样本的宿主星系系统地显示出更大的σ*、恒星质量和浓度，以及更老的光度加权平均恒星年龄;它们在射电性质上没有显着差异。这些双峰特征可能是由于窄线区域运动学或二元黑洞。统计特性并没有显示出强烈的偏好或反对任何一种情况下，空间分辨光学成像，光谱学，无线电或X射线后续需要得出明确的结论。
We present a sample of 167 type 2 active galactic nuclei (AGNs) with double-peaked [O iii] λλ4959,5007 narrow emission lines, selected from the Seventh Data Release of the Sloan Digital Sky Survey. The double-peaked profiles can be well modeled by two velocity components, blueshifted and redshifted from the systemic velocity. Half of these objects have a more prominent redshifted component. In cases where the Hβ emission line is strong, it also shows two velocity components whose line-of-sight (LOS) velocity offsets are consistent with those of [O iii]. The relative LOS velocity offset between the two components is typically a few hundred km s-1, larger by a factor of ∼1.5 than the line full width at half maximum of each component. The offset correlates with the host stellar velocity dispersion σ*. The host galaxies of this sample show systematically larger σ*, stellar masses, and concentrations, and older luminosity-weighted mean stellar ages than a regular type 2 AGN sample matched in redshift, [O iii] λ5007 equivalent width, and luminosity; they show no significant difference in radio properties. These double-peaked features could be due to narrow-line region kinematics, or binary black holes. The statistical properties do not show strong preference for or against either scenario, and spatially resolved optical imaging, spectroscopy, radio or X-ray follow-up are needed to draw firm conclusions.