Optical and Near-Infrared Imaging of the IRAS 1 Jy Sample of Ultraluminous Infrared Galaxies. II. The Analysis
Optical and Near-Infrared Imaging of the IRAS 1 Jy Sample of Ultraluminous Infrared Galaxies. II. The Analysis
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DOI：
10.1086/343844
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发表时间：
2002-07
期刊：
影响因子：
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通讯作者：
S. Veilleux;D.-C. Kim;D. Sanders
中科院分区：
文献类型：
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作者：
S. Veilleux;D.-C. Kim;D. Sanders
118个超发光红外星系（ULIGs）的IRAS 1 Jy样本的R和K '图谱已在论文I中发表。本文讨论了这些图像的分析结果，并补充了在凯克获得的新的光谱数据。在Jy样本中，除了一个天体外，其他所有天体都显示出强烈的潮汐相互作用/合并的迹象。涉及两个以上星系的多重合并在118个星系中不超过5个（0.2个），而更明亮的系统（>1012.5 L☉）都显示出强烈的趋势，是具有单一核心的高级合并。1 Jy样品双星系统中的单个星系在主星等（光度）上分布广泛，在R波段平均为-21.02±0.76等（0.85 L*），在K′波段平均为-23.98±1.25等（0.90 L*）， R波段或K′波段的光度比一般小于~4。单核ULIGs在宿主亮度（光度）上也有广泛的分布，在R处平均为-21.77±0.92等（1.69 L*），在K′处平均为-25.03±0.94等（2.36）。这些分布与类星体的分布有相当大的重叠。同样的说法也适用于uig和类星体宿主的R-K色。对单核源中宿主星系表面亮度分布的分析表明，约73%的R和K '表面亮度分布可以用类椭圆R1/4定律拟合。这些椭圆型1 Jy系统的光度和r波段轴比分布与正常的（非活动的）中等光度椭圆星系相似，并遵循一些散射的μ -re关系，这使人们相信，如果这些物体摆脱了多余的气体或将这些气体转化为恒星，其中一些物体可能最终成为中等光度椭圆星系。这些椭圆状的宿主在具有Seyfert 1核（83%）、Seyfert 2光学特征（69%）或中红外（ISO） AGN特征（80%）的合并残留物中最常见。这些ulig的平均半光半径在R为4.80±1.37 kpc，在K′为3.48±1.39 kpc，是典型的中等光度椭圆。这些值与哈勃太空望远镜（HST）最近在H获得的类星体测量值非常一致，但它们比在r获得的其他HST测量值系统地低。两个类星体数据集之间差异的原因尚不清楚。总的来说，本研究的结果与合并驱动的演化序列“冷ULIGs→热ULIGs→类星体”是一致的。然而，这个简单的图景似乎存在许多例外（例如，41个高级合并中有46%没有明显的塞弗特活动迹象）。这强调了使用一个大的同质样本的重要性，如1jy样本，以得出统计上有意义的结论；小样本量和/或选择标准不均匀的问题一直困扰着过去许多发光红外星系的研究。
An R and K′ atlas of the IRAS 1 Jy sample of 118 ultraluminous infrared galaxies (ULIGs) was presented in a companion paper (our Paper I). The present paper discusses the results from the analysis of these images supplemented with new spectroscopic data obtained at Keck. All but one object in the 1 Jy sample show signs of a strong tidal interaction/merger. Multiple mergers involving more than two galaxies are seen in no more than five of the 118 ( 0.2), and the more luminous systems (>1012.5 L☉) all show a strong tendency to be advanced mergers with a single nucleus. The individual galaxies in the binary systems of the 1 Jy sample show a broad distribution in host magnitudes (luminosities) with a mean of -21.02 ± 0.76 mag (0.85 L*) at R and -23.98 ± 1.25 mag (0.90 L*) at K′, and a R- or K′-band luminosity ratio generally less than ~4. Single-nucleus ULIGs also show a broad distribution in host magnitudes (luminosities) with an average of -21.77 ± 0.92 mag (1.69 L*) at R and -25.03 ± 0.94 mag (2.36) at K′. These distributions overlap considerably with those of quasars. The same statement applies to R-K' colors in ULIG and quasar hosts. An analysis of the surface brightness profiles of the host galaxies in single-nucleus sources reveals that about 73% of the R and K′ surface brightness profiles are fitted adequately by an elliptical-like R1/4 law. These elliptical-like 1 Jy systems have luminosity and R-band axial ratio distributions that are similar to those of normal (inactive) intermediate-luminosity ellipticals and follow with some scatter the same μe-re relation, giving credence to the idea that some of these objects may eventually become intermediate-luminosity elliptical galaxies if they get rid of their excess gas or transform this gas into stars. These elliptical-like hosts are most common among merger remnants with Seyfert 1 nuclei (83%), Seyfert 2 optical characteristics (69%), or mid-infrared (ISO) AGN signatures (80%). The mean half-light radius of these ULIGs is 4.80 ± 1.37 kpc at R and 3.48 ± 1.39 kpc at K′, typical of intermediate-luminosity ellipticals. These values are in excellent agreement with recent quasar measurements obtained at H with the Hubble Space Telescope (HST), but they are systematically lower than other HST measurements derived at R. The reason for this discrepancy between the two quasar data sets is not known. In general, the results from the present study are consistent with the merger-driven evolutionary sequence "cool ULIGs→warm ULIGs→quasars." However, many exceptions appear to exist to this simple picture (e.g., 46% of the 41 advanced mergers show no obvious signs of Seyfert activity). This underlines the importance of using a large homogeneous sample like the 1 Jy sample to draw statistically meaningful conclusions; the problems of small sample size and/or inhomogeneous selection criteria have plagued many studies of luminous infrared galaxies in the past.