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arXiv 1306.3958astro-ph.CO
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亚毫米星系的高分辨率近红外成像

High resolution near-infrared imaging of submillimeter galaxies

Paula Aguirre, Andrew J. Baker, Felipe Menanteau, Dieter Lutz, Linda J. Tacconi

摘要:

利用哈勃空间望远镜的NICMOS相机对10个亚毫米星系进行了F110 W(~J)和F160 W(~H)观测。我们的目标在2.20<z<2.81范围内的光学红移由毫米CO或中红外光谱证实,保证了两个带对静止框架光学进行采样,巴尔末断裂落在它们之间。在两个波段中检测到十个中的八个,而仅在F160 W中检测到两个。我们研究了他们的F160 W形态,应用最大的去混合检测算法来区分多个单组分配置,导致重新评估几个对象。基于我们的NICMOS成像和/或以前的动力学证据,我们确定了5个SMG作为多个源,我们解释为合并系统。此外,我们计算形态参数不对称性(A)和基尼系数(G);由于我们的样品的有限的红移范围,我们恢复的趋势,多组分,合并样的形态反映在较高的不对称性。我们分析了恒星星族的9个对象与F110 W/F160 W测光,使用档案HST光学数据时可用。对于多个系统,我们能够对构成SMG的各个组件进行建模。根据现有的数据,我们不能区分恒星的形成历史,但是我们限制了类合并SMG系统的恒星质量和质量比,得到了我们完整样本的平均log(M_*/M_sun)=10.9+/-0.2,个别值log(M_*/M_sun)~9.6-11.8。最小和最大质量系统的形态和质量比分别与主要合并和冷吸积SMG形成情景的预测相匹配,这表明这两个通道可能在人口起源中发挥作用。

英文摘要:

We present F110W (~J) and F160W (~H) observations of ten submillimeter galaxies (SMGs) obtained with the Hubble Space Telescope's (HST's) NICMOS camera. Our targets have optical redshifts in the range 2.20<z<2.81 confirmed by millimeter CO or mid-IR spectroscopy, guaranteeing that the two bands sample the rest-frame optical with the Balmer break falling between them. Eight of ten are detected in both bands, while two are detected in F160W only. We study their F160W morphologies, applying a maximum-deblending detection algorithm to distinguish multiple- from single-component configurations, leading to reassessments for several objects. Based on our NICMOS imaging and/or previous dynamical evidence we identify five SMGs as multiple sources, which we interpret as merging systems. Additionally, we calculate morphological parameters asymmetry (A) and Gini coefficient (G); thanks to our sample's limited redshift range we recover the trend that multiple-component, merger-like morphologies are reflected in higher asymmetries. We analyze the stellar populations of nine objects with F110W/F160W photometry, using archival HST optical data when available. For multiple systems, we are able to model the individual components that build up an SMG. With the available data we cannot discriminate among star formation histories, but we constrain stellar masses and mass ratios for merger-like SMG systems, obtaining a mean log(M_*/M_sun)=10.9+/-0.2 for our full sample, with individual values log(M_*/M_sun)~9.6-11.8. The morphologies and mass ratios of the least and most massive systems match the predictions of the major-merger and cold accretion SMG formation scenarios, respectively, suggesting that both channels may have a role in the population's origin.

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