ALMA [NII] 205 micron Imaging Spectroscopy of the Interacting Galaxy System BRI 1202-0725 at Redshift 4.7
ALMA [NII] 205 micron Imaging Spectroscopy of the Interacting Galaxy System BRI 1202-0725 at Redshift 4.7
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ALMA [NII] 相互作用星系系统 BRI 1202-0725 在 Redshift 4.7 下的 205 微米成像光谱
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发表时间：
2017
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通讯作者：
Lei Zhu
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作者：
Nanyao Lu;Yinghe Zhao;Tanio Diaz-Santos;C. Kevin Xu;Vassilis Charm;aris;Yu Gao;Paul P. van der Werf;George C. Privon;Hanae Inami;Dimitra Rigopoulou;David B. S;ers;Lei Zhu
我们给出了阿塔卡马大型毫米/亚毫米阵列在[N II] 205μm精细结构线（以下简称[N II]）和BRI 1202-0725的基础连续体上的成像结果。BRI 1202-0725是一个z = 4.7的相互作用星系系统，由一个类星体（QSO）、一个亚毫米星系（SMG）和两个Lyα发射体组成，它们都在QSO的25 kpc范围内。我们在[N Ⅱ]和连续谱中探测到了类星体和SMG。在~ 1″（或6.6 kpc）分辨率下，类星体和SMG都以[N II]分辨率分辨，解卷积主轴分别为~ 9和~ 14 kpc。相比之下，它们的连续谱发射更加紧凑，即使在分辨率提高到1000 ″时也无法分辨。[N II]通量与现有CO（7-6）通量的比值用于约束尘埃温度（T尘埃），以便更准确地确定FIR光度L FIR。我们对这两个星系的尘埃T的最佳估计值为43（±2）K（假设发射率指数β = 1.8）。计算得到的LCO（7-6）/LFIR比值与本地亮红外星系的比值在统计上是一致的，证实了LCO（7-6）跟踪了这些星系中的星星形成（SF）速率（SFR）。我们估计，假设Chabrier初始质量函数，类星体（SMG）正在进行的SF的SFR为5.1（6.9）× 103 M yr-1（±30%），发生在1.3（1.5）kpc的直径（半最大值）内，并将在10（7）× 107年内消耗现有的5（5）× 1011 M的分子气体。
We present the results from Atacama Large Millimeter/submillimeter Array imaging in the [N II] 205μm fine-structure line (hereafter [N II]) and the underlying continuum of BRI 1202-0725, an interacting galaxy system at z = 4.7, consisting of a quasi-stellar object (QSO), a submillimeter galaxy (SMG), and two Lyα emitters, all within ˜25 kpc of the QSO. We detect the QSO and SMG in both [N II] and continuum. At the ˜1″ (or 6.6 kpc) resolution, both the QSO and SMG are resolved in [N II], with the de-convolved major axes of ˜9 and ˜14 kpc, respectively. In contrast, their continuum emissions are much more compact and unresolved even at an enhanced resolution of ˜0.″7. The ratio of the [N II] flux to the existing CO(7-6) flux is used to constrain the dust temperature (T dust) for a more accurate determination of the FIR luminosity L FIR. Our best estimated T dust equals 43 (±2) K for both galaxies (assuming an emissivity index β = 1.8). The resulting L CO(7-6)/L FIR ratios are statistically consistent with that of local luminous infrared galaxies, confirming that L CO(7-6) traces the star formation (SF) rate (SFR) in these galaxies. We estimate that the ongoing SF of the QSO (SMG) has an SFR of 5.1 (6.9) × 103 M ⊙ yr-1 (±30%) assuming Chabrier initial mass function, takes place within a diameter (at half maximum) of 1.3 (1.5) kpc, and will consume the existing 5 (5) × 1011 M ⊙ of molecular gas in 10 (7) × 107 years.