arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 2011.13319astro-ph.GA
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用ALMA观测的$z \approx 7.7$星系中令人困惑的未探测到[O PDKEEPAAAAA]和[C II ]

A puzzling non-detection of [O III] and [C II] from a $z \approx 7.7$ galaxy observed with ALMA

C. Binggeli, A. K. Inoue, T. Hashimoto, M. C. Toribio, E. Zackrisson, S. Ramstedt, K. Mawatari, Y. Harikane, H. Matsuo, T. Okamoto, K. Ota, I. Shimizu, Y. Tamur… 展开作者

C. Binggeli, A. K. Inoue, T. Hashimoto, M. C. Toribio, E. Zackrisson, S. Ramstedt, K. Mawatari, Y. Harikane, H. Matsuo, T. Okamoto, K. Ota, I. Shimizu, Y. Tamura, Y. Taniguchi, H. Umehata

摘要:

描述早期宇宙中星系群的特征是理解这些天体演化及其在宇宙再电离中所起作用的关键。然而,在最高红移的观测数量是迄今为止,很少。为了揭示高红移宇宙中星系及其星际介质的性质,我们在阿塔卡马大型毫米/亚毫米波阵(ALMA)的$z=7.664$观测了Lyman-$α$发射星系z7\_GSD\_3811.利用ALMA对恒星形成星系z7\_GSD\_3811的远红外[O III] 88 $μm$、[C II] 158 $μm$发射谱线和尘埃连续谱进行了观测。我们结合这些测量与早期的观测在休息帧紫外线(UV),以表征对象,并比较结果的早期研究观察[O III]和[C II]发射高红移星系。在z7\_GSD\_3811位置未检测到[O III] 88 $μm$和[C II] 158 $μm$发射线,$3σ$上限分别为$1.6 \ \times \ 10^{8} \ L_{\odot}$和$4.0 \ \times \ 10^{7} \ L_{\odot}$。我们没有检测到任何尘埃连续带6或带8。在频带8和频带6连续谱中测量的均方根分别为26和9.9 $μJy \ beam^{-1}$。与其他几个高红移星系类似,z7_GSD_3811的[C II]辐射相对于本星系而言,其恒星形成率较低。此外,我们的[O III]线光度的上限是低于所有以前观察到的[O III]线在高红移星系具有类似的紫外光度。我们的ALMA波段6和8尘埃连续体观测表明,z7\_GSD\_3811可能具有较低的尘埃含量,而我们对[O III]和[C II]线的未检测可能表明z7\_GSD\_3811具有较低的金属丰度($Z \lesssim 0.1 \ Z_{\odot}$)。

英文摘要:

Characterizing the galaxy population in the early Universe holds the key to understanding the evolution of these objects and the role they played in cosmic reionization. However, the number of observations at the very highest redshifts are to date, few. In order to shed light on the properties of galaxies in the high-redshift Universe and their interstellar media, we observe the Lyman-$α$ emitting galaxy z7\_GSD\_3811 at $z=7.664$ with band 6 and 8 at the Atacama Large Millimeter/submillimeter Array (ALMA). We target the far-infrared [O III] 88 $μm$, [C II] 158 $μm$ emission lines and dust continuum in the star-forming galaxy z7\_GSD\_3811 with ALMA. We combine these measurements with earlier observations in the rest-frame ultraviolet (UV) in order to characterize the object, and compare results to those of earlier studies observing [O III] and [C II] emission in high-redshift galaxies. The [O III] 88 $μm$ and [C II] 158 $μm$ emission lines are undetected at the position of z7\_GSD\_3811, with $3σ$ upper limits of $1.6 \ \times \ 10^{8} \ L_{\odot}$ and $4.0 \ \times \ 10^{7} \ L_{\odot}$, respectively. We do not detect any dust continuum in band 6 nor band 8. The measured rms in the band 8 and band 6 continuum is 26 and 9.9 $μJy \ beam^{-1}$, respectively. Similar to several other high-redshift galaxies, z7\_GSD\_3811 exhibits low [C II] emission for its star formation rate compared to local galaxies. Furthermore, our upper limit on the [O III] line luminosity is lower than all the previously observed [O III] lines in high-redshift galaxies with similar ultraviolet luminosities. Our ALMA band 6 and 8 dust continuum observations imply that z7\_GSD\_3811 likely has a low dust content, and our non-detections of the [O III] and [C II] lines could indicate that z7\_GSD\_3811 has a low metallicity ($Z \lesssim 0.1 \ Z_{\odot}$).

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