Low gas-phase metallicities of ultraluminous infrared galaxies are a result of dust obscuration
Low gas-phase metallicities of ultraluminous infrared galaxies are a result of dust obscuration
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DOI：
10.1038/s41550-022-01679-y
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发表时间：
2021-11
期刊：
影响因子：
14.1
通讯作者：
N. Chartab;A. Cooray;Jingzhe Ma;H. Nayyeri;Preston Zilliot;Jonathan Lopez;D. Fadda;R. Herrera-Camus;M. Malkan;D. Rigopoulou;K. Sheth;J. Wardlow
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文献类型：
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作者：
N. Chartab;A. Cooray;Jingzhe Ma;H. Nayyeri;Preston Zilliot;Jonathan Lopez;D. Fadda;R. Herrera-Camus;M. Malkan;D. Rigopoulou;K. Sheth;J. Wardlow
光学光谱测量表明，在本宇宙中被称为超发光红外星系(ULIRGs)的尘埃星系中的气体，其金属含量明显低于质量相似的恒星形成星系中的气体。这种低金属含量导致了这样的说法，即ULIRG主要是由远距离落入这些星系合并系统的贫金属气体提供燃料的。在这里，我们报告了一组新的气相金属丰度测量，这些测量是在本地ULIRG中使用追踪氧和氮的远红外波长的发射线进行的。这些新数据表明，ULIRGS建立在由恒星质量、金属丰度和恒星形成率决定的基本金属丰度关系上，作为关键的观测参数。新的数据表明，来自光学发射线的金属丰度不足可能是由于与星暴相关的严重尘埃遮蔽所致，而不是缺乏金属的气体吸积。由于在恒星形成的顶峰时期，被尘埃遮挡的红外明亮星系主导着宇宙的恒星形成率密度，我们警告不要只使用静止框架光学测量来研究红移2-3的星系的金属丰度。
Optical spectroscopic measurements show that gas in dusty, starbursting galaxies known as ultraluminous infrared galaxies (ULIRGs) in the local Universe has a significantly lower metal content than that of gas in star-forming galaxies with similar masses. This low metal content has resulted in the claim that ULIRGs are primarily fuelled by metal-poor gas falling into those galaxy merger systems from large distances. Here we report a new set of gas-phase metal abundance measurements taken in local ULIRGs using emission lines at far-infrared wavelengths tracing oxygen and nitrogen. These new data show that ULIRGs lie on the fundamental metallicity relation determined by the stellar mass, metal abundance and star formation rate as the key observational parameters. Instead of metal-poor gas accretion, the new data suggest that the underabundance of metals derived from optical emission lines is probably due to heavy dust obscuration associated with the starburst. As dust-obscured, infrared-bright galaxies dominate the star formation rate density of the Universe during the peak epoch of star formation, we caution the use of rest-frame optical measurements alone to study the metal abundances of galaxies at redshifts of 2–3.