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arXiv 2407.00977astro-ph.GA
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在高红移射电星系中探测到的进行中与化石化的大尺度外流:TN J0924$-$2201在$z=5.174$处的[C II]观测

Ongoing and fossil large-scale outflows detected in a high-redshift radio galaxy: [C II] observations of TN J0924$-$2201 at $z=5.174$

Kianhong Lee, Masayuki Akiyama, Kotaro Kohno, Daisuke Iono, Masatoshi Imanishi, Bunyo Hatsukade, Hideki Umehata, Tohru Nagao, Yoshiki Toba, Xiaoyang Chen, Fumi … 展开作者

Kianhong Lee, Masayuki Akiyama, Kotaro Kohno, Daisuke Iono, Masatoshi Imanishi, Bunyo Hatsukade, Hideki Umehata, Tohru Nagao, Yoshiki Toba, Xiaoyang Chen, Fumi Egusa, Kohei Ichikawa, Takuma Izumi, Naoki Matsumoto, Malte Schramm, Kenta Matsuoka

AI总结:

利用ALMA对z>5射电星系TN J0924-2201的[C II]观测,发现Lyα最大速度偏移及红移子结构,结合伴星系非探测,揭示AGN驱动的进行中与化石化大尺度外流正在清除早期宇宙过密区中央大质量星系的分子气体。

摘要:

我们展示了阿塔卡马大型毫米/亚毫米波阵列(Atacama Large Millimeter/submillimeter Array)对TN J0924$-$2201的[C II] 158 $μ$m谱线及其下方连续谱辐射的观测结果,该星系是$z>5$处已知最遥远的射电星系之一。[C II]谱线和1毫米连续谱辐射均在宿主星系中被探测到。由[C II]谱线导出的系统红移为$z_{\rm [C II]}=5.1736\pm0.0002$,表明Ly$α$谱线红移了$1035\pm10$ km s$^{-1}$的速度,这是迄今在$z>5$处记录到的[C II]与Ly$α$谱线之间最大的速度偏移。在宿主星系的中心区域,我们识别出一个红移的[C II]子结构,其速度为$702\pm17$ km s$^{-1}$,与速度为$500\pm10$ km s$^{-1}$的CIV谱线接近。其位置和速度偏移与外流壳层结构模型一致,与Ly$α$的大速度偏移相符。三个CO(1--0)探测到的伴星系中[C II]和尘埃辐射的未探测表明,基于光解离区模型,它们的性质与矮星系不同。鉴于它们约$\sim1500$ km s$^{-1}$的大速度,由活动星系核(AGN)驱动的外流分子云是最合理的解释,且它们可能超过一个$10^{13}\\,M_{\odot}$暗物质晕的逃逸速度。这些结果表明,TN J0924$-$2201具有进行中的和化石化的大尺度外流,正处于早期宇宙中一个过密区域内的中央大质量星系中清除分子气体的独特阶段。宿主星系中的一个含尘HI吸收体是另一种可能的解释。

英文摘要:

We present Atacama Large Millimeter/submillimeter Array observations of the [C II] 158 $μ$m line and the underlying continuum emission of TN J0924$-$2201, which is one of the most distant known radio galaxies at $z>5$. The [C II] line and 1-mm continuum emission are detected at the host galaxy. The systemic redshift derived from the [C II] line is $z_{\rm [C II]}=5.1736\pm0.0002$, indicating that the Ly$α$ line is redshifted by a velocity of $1035\pm10$ km s$^{-1}$, marking the largest velocity offset between the [C II] and Ly$α$ lines recorded at $z>5$ to date. In the central region of the host galaxy, we identified a redshifted substructure of [C II] with a velocity of $702\pm17$ km s$^{-1}$, which is close to the CIV line with a velocity of $500\pm10$ km s$^{-1}$. The position and the velocity offsets align with a model of an outflowing shell structure, consistent with the large velocity offset of Ly$α$. The non-detection of [C II] and dust emission from the three CO(1--0)-detected companions indicates their different nature compared to dwarf galaxies based on the photodissociation region model. Given their large velocity of $\sim1500$ km s$^{-1}$, outflowing molecular clouds induced by the AGN is the most plausible interpretation, and they may exceed the escape velocity of a $10^{13}\,M_{\odot}$ halo. These results suggest that TN J0924$-$2201, with the ongoing and fossil large-scale outflows, is in a distinctive phase of removing molecular gas from a central massive galaxy in an overdense region in the early universe. A dusty HI absorber at the host galaxy is an alternative interpretation.

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