MOSFIRE and LDSS3 Spectroscopy for an [O II] Blob at z = 1.18: Gas Outflow and Energy Source
MOSFIRE and LDSS3 Spectroscopy for an [O II] Blob at z = 1.18: Gas Outflow and Energy Source
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z = 1.18 时 [O II] 斑点的 MOSFIRE 和 LDSS3 光谱：气体流出和能源
DOI：
10.1088/0004-637x/794/2/129
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发表时间：
2014
期刊：
影响因子：
--
通讯作者：
Yuma et al.
中科院分区：
文献类型：
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作者：
Harikane;Ouchi;Yuma et al.
我们报道了我们的Keck/MOSFIRE和Magellan/低色散巡天摄谱仪对一个[O ii] BloB，O ii B 10的光谱观测结果，该星系是一个高z星系，其空间扩展的[O ii] λλ3726，3729发射超过30 kpc，最近由Subaru大面积窄带巡天发现。用[O iii] λλ4959、5007和Hβ发射线确定了O ii B 10的系统红移z= 1.18。我们确定了Fe ii λ2587和Mg ii λλ2796，2804吸收线分别从系统红移蓝移了80±50和260±40 km s− 1，这表明气体从O ii B 10流出，速度为180 -260 km s− 1。这个流出速度与逃逸速度（250±140 km s− 1）相当，逃逸速度是在奇异等温晕势分布假设下估计的。部分流出的气体可能会从O ii B 10的晕中逃逸出来，抑制O ii B 10的恒星形成（SF）活动。我们估计了质量负载因子η，即质量流出率与SF率的比值，并得到η> 0.8±0.1，这与包括U/LIRG和活动星系核（AGN）在内的低z星暴相比是相对较高的。根据现有数据，外流的主要能源尚不清楚。虽然在X射线数据中没有发现活动星系核的特征，但在线诊断图中，O ii B 10福尔斯落在活动星系核/成星复合区。外流可能是由SF和一个2型活动星系核提供动力，而活动星系核的窄FWHM发射线宽度为70-130 km s-1。这是第一个详细的光谱研究氧线斑点，包括逃逸速度的分析，质量负载因子，和AGN的存在下，是一个重要的一步，了解氧线斑点的性质和气体流出和SF淬火在高红移之间的关系。
We report our Keck/MOSFIRE and Magellan/Low-Dispersion Survey Spectrograph spectroscopy for an [O ii] Blob, O ii B 10, that is a high-z galaxy with spatially extended [O ii] λλ3726, 3729 emission over 30 kpc recently identified by a Subaru large-area narrowband survey. The systemic redshift of O ii B 10 is z= 1.18 securely determined with [O iii] λλ4959, 5007 and Hβ emission lines. We identify Fe ii λ2587 and Mg ii λλ2796, 2804 absorption lines blueshifted from the systemic redshift by 80±50 and 260±40 km s− 1, respectively, which indicates gas outflow from O ii B 10 with the velocity of∼ 80–260 km s− 1. This outflow velocity is comparable with the escape velocity, 250±140 km s− 1, estimated under the assumption of a singular isothermal halo potential profile. Some fraction of the outflowing gas could escape from the halo of O ii B 10, suppressing O ii B 10's star-formation (SF) activity. We estimate a mass loading factor, η, that is a ratio of mass outflow rate to SF rate, and obtain η> 0.8±0.1, which is relatively high compared with low-z starbursts including U/LIRGs and active galactic nuclei (AGNs). The major energy source of the outflow is unclear with the available data. Although no signature of AGNs is found in the X-ray data, O ii B 10 falls in the AGN/star-forming composite region in the line diagnostic diagrams. It is possible that the outflow is powered by SF and a type-2 AGN with narrow FWHM emission line widths of 70–130 km s− 1. This is the first detailed spectroscopic study of oxygen-line blobs that includes analyses of the escape velocity, the mass loading factor, and the presence of an AGN, and is a significant step to understanding the nature of oxygen-line blobs and the relation between gas outflow and SF quenching at high redshift.