We present new Atacama Large Millimeter/submillimeter Array (ALMA) observations of a starburst galaxy at cosmic noon hosting a radio-loud active galactic nucleus: PKS 0529-549 at z = 2.57. To investigate the conditions of its cold interstellar medium, we use ALMA observations that spatially resolve the [C i] fine-structure lines, [C i] (2–1) and [C i] (1–0), CO rotational lines, CO (7–6) and CO (4–3), and the rest-frame continuum emission at 461 and 809 GHz. The four emission lines display different morphologies, suggesting spatial variation in the gas excitation conditions. The radio jets have just broken out of the molecular gas but not through the more extended ionized gas halo. The [C i] (2–1) emission is more extended (≈8 kpc × 5 kpc) than detected in previous shallower ALMA observations. The [C i] luminosity ratio implies an excitation temperature of 44 ± 16 K, similar to the dust temperature. Using the [C i] lines, CO (4–3), and 227 GHz dust continuum, we infer the mass of molecular gas Mmol using three independent approaches and typical assumptions in the literature. All approaches point to a massive molecular gas reservoir of about 1011M☉, but the exact values differ by up to a factor of 4. Deep observations are critical in correctly characterizing the distribution of cold gas in high-redshift galaxies, and highlight the need to improve systematic uncertainties in inferring accurate molecular gas masses.

中文翻译：

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使用 ALMA 对 [C i]、CO 和尘埃发射的观测，对 z ≈ 2.6 处活跃的星暴星系进行分子气体质量测量


我们提出了新的阿塔卡马大型毫米/亚毫米阵列 （ALMA） 观测数据，该星系在宇宙正午承载着一个射电响亮的活跃星系核：PKS 0529-549，z = 2.57。为了研究其寒冷星际介质的条件，我们使用 ALMA 观测在空间上解析 [C i] 精细结构线、[C i] （2-1） 和 [C i] （1-0）、CO 旋转线、CO （7-6） 和 CO （4-3），以及 461 和 809 GHz 的静止坐标系连续发射。四条发射线显示出不同的形态，表明气体激发条件存在空间变化。射电射流刚刚从分子气体中爆发出来，但没有穿过更延伸的电离气体晕。[C i] （2–1） 发射比以前较浅的 ALMA 观测中检测到的更广泛（≈8 kpc × 5 kpc）。[C i] 光度比意味着激发温度为 44 ± 16 K，类似于尘埃温度。使用 [C i] 线、CO （4-3） 和 227 GHz 尘埃连续体，我们使用三种独立的方法和文献中的典型假设来推断分子气体 Mmol 的质量。所有方法都指向一个约 1011M☉ 的巨大分子气藏，但确切值相差高达 4 倍。深度观测对于正确描述高红移星系中冷气体的分布至关重要，并突出了在推断准确分子气体质量时提高系统不确定性的必要性。