Uncovering the stellar structure of the dusty star-forming galaxy GN20 at z = 4.055 with MIRI/JWST
Uncovering the stellar structure of the dusty star-forming galaxy GN20 at z = 4.055 with MIRI/JWST
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使用 MIRI/JWST 揭示 z = 4.055 处尘埃恒星形成星系 GN20 的恒星结构
DOI：
10.1051/0004-6361/202346535
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发表时间：
2023
影响因子：
6.5
通讯作者：
Colina L
中科院分区：
文献类型：
--
作者：
Colina L
高红移（z> 4）的亮红外星系包括极端的恒星暴，它们在短时间内（即1亿年或更短）形成恒星质量。这些星系被认为是中等红移（z ≥ 2）的大质量静止星系的祖先，但它们的恒星结构和形成尚不清楚。 在这里，我们展示了GN 20的第一个空间分辨近红外（静止帧1.1 μm）图像，GN 20是迄今为止已知的最明亮的尘埃恒星形成星系之一，在宇宙只有1.5 Gyr的时代被观测到。这张由JWST中红外线仪器（MIRI/JWST）拍摄的5.6 μm图像显示，GN 20是一个非常明亮的星系（M1.1 μm，AB= −25.01，未经内部消光校正），其恒星结构由一个明显的中央源和一个扩展的包层组成。 中心源是一个未分辨的原子核，携带总通量的9%。核心与冷尘埃发射的峰值共对齐，并从紫外恒星发射偏移3.9千秒差距。扩散恒星的信封是类似的大小（3.6千秒差距的有效半径）的clusified CO分子气体分布。恒星包层的质心与未分辨的核心偏移了1千秒差距，这表明GN 20参与了一个相互作用或合并事件，这是由它作为原星系团中最亮的星系所支持的。其他暗淡的恒星团似乎与一些紫外和CO团有关。GN 20的恒星尺寸比已知的球状体、盘状体和不规则星系大3到5倍，而它的尺寸和低的Sérsic指数与红移为2的相同质量的尘埃红外发光星系（1011 M <$）相似。 GN 20拥有演化成一个中等红移的大质量球状静止星系所需的所有要素：它是一个大而明亮的星系，atz= 4.05，参与了一个以恒星核为中心的短而大质量的星暴，并延伸到整个星系，半径为4 kpc，可能是由与原星系团成员的相互作用或合并引起的。
Luminous infrared galaxies at high redshifts (z> 4) include extreme starbursts that build their stellar mass over short periods of time, that is, of 100 Myr or less. These galaxies are considered to be the progenitors of massive quiescent galaxies at intermediate redshifts (z∼ 2) but their stellar structure and buildup is unknown. Here, we present the first spatially resolved near-infrared (rest-frame 1.1 μm) imaging of GN20, one of the most luminous dusty star-forming galaxies known to date, observed at an epoch when the Universe was only 1.5 Gyr old. The 5.6 μm image taken with the JWST Mid-Infrared Instrument (MIRI/JWST) shows that GN20 is a very luminous galaxy (M1.1 μm, AB= −25.01, uncorrected for internal extinction), with a stellar structure composed of a conspicuous central source and an extended envelope. The central source is an unresolved nucleus that carries 9% of the total flux. The nucleus is co-aligned with the peak of the cold dust emission, and offset by 3.9 kpc from the ultraviolet stellar emission. The diffuse stellar envelope is similar in size (3.6 kpc effective radius) to the clumpy CO molecular gas distribution. The centroid of the stellar envelope is offset by 1 kpc from the unresolved nucleus, suggesting GN20 is involved in an interaction or merger event supported by its location as the brightest galaxy in a proto-cluster. Additional faint stellar clumps appear to be associated with some of the UV- and CO-clumps. The stellar size of GN20 is larger by a factor of about 3 to 5 than known spheroids, disks, and irregulars atz∼ 4, while its size and low Sérsic index are similar to those measured in dusty, infrared luminous galaxies at redshift 2 of the same mass (∼1011M⊙). GN20 has all the ingredients necessary for evolving into a massive spheroidal quiescent galaxy at intermediate redshift: it is a large, luminous galaxy atz= 4.05 involved in a short and massive starburst centred in the stellar nucleus and extended over the entire galaxy, out to radii of 4 kpc, and likely induced by the interaction or merger with a member of the proto-cluster.