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The nature of an ultra-faint galaxy in the cosmic dark ages seen with JWST
Nature ( IF 50.5 ) Pub Date : 2023-05-17 , DOI: 10.1038/s41586-023-05994-w
Guido Roberts-Borsani 1 , Tommaso Treu 1 , Wenlei Chen 2 , Takahiro Morishita 3 , Eros Vanzella 4 , Adi Zitrin 5 , Pietro Bergamini 4, 6 , Marco Castellano 7 , Adriano Fontana 7 , Karl Glazebrook 8 , Claudio Grillo 6, 9 , Patrick L Kelly 2 , Emiliano Merlin 7 , Themiya Nanayakkara 8 , Diego Paris 7 , Piero Rosati 4, 10 , Lilan Yang 11 , Ana Acebron 6, 9 , Andrea Bonchi 7, 12 , Kit Boyett 13, 14 , Maruša Bradač 15, 16 , Gabriel Brammer 17, 18 , Tom Broadhurst 19, 20, 21 , Antonello Calabró 7 , Jose M Diego 22 , Alan Dressler 23 , Lukas J Furtak 5 , Alexei V Filippenko 24 , Alaina Henry 25, 26 , Anton M Koekemoer 25 , Nicha Leethochawalit 27 , Matthew A Malkan 1 , Charlotte Mason 17, 18 , Amata Mercurio 28, 29 , Benjamin Metha 1, 13, 14 , Laura Pentericci 7 , Justin Pierel 25 , Steven Rieck 2 , Namrata Roy 26 , Paola Santini 7 , Victoria Strait 17, 18 , Robert Strausbaugh 30 , Michele Trenti 13, 14 , Benedetta Vulcani 31 , Lifan Wang 32 , Xin Wang 33, 34, 35 , Rogier A Windhorst 36
Affiliation  

In the first billion years after the Big Bang, sources of ultraviolet (UV) photons are believed to have ionized intergalactic hydrogen, rendering the Universe transparent to UV radiation. Galaxies brighter than the characteristic luminosity L* (refs. 1,2) do not provide enough ionizing photons to drive this cosmic reionization. Fainter galaxies are thought to dominate the photon budget; however, they are surrounded by neutral gas that prevents the escape of the Lyman-α photons, which has been the dominant way to identify them so far. JD1 was previously identified as a triply-imaged galaxy with a magnification factor of 13 provided by the foreground cluster Abell 2744 (ref. 3), and a photometric redshift of z ≈ 10. Here we report the spectroscopic confirmation of this very low luminosity (≈0.05 L*) galaxy at z = 9.79, observed 480 Myr after the Big Bang, by means of the identification of the Lyman break and redward continuum, as well as multiple 4σ emission lines, with the Near-InfraRed Spectrograph (NIRSpec) and Near-InfraRed Camera (NIRCam) instruments. The combination of the James Webb Space Telescope (JWST) and gravitational lensing shows that this ultra-faint galaxy (MUV = −17.35)—with a luminosity typical of the sources responsible for cosmic reionization—has a compact (≈150 pc) and complex morphology, low stellar mass (107.19M) and subsolar (≈0.6 Z) gas-phase metallicity.



中文翻译:

JWST 观测到的宇宙黑暗时代超微弱星系的性质

在大爆炸后的第一个十亿年里,紫外线 (UV) 光子的来源被认为已经电离了星际氢,使宇宙对紫外线辐射透明。比特征光度L *(参考文献 1,2)亮的星系不能提供足够的电离光子来驱动这种宇宙再电离。较暗的星系被认为支配着光子预算;然而,它们被中性气体包围,阻止了莱曼-α光子的逃逸,而莱曼-α光子一直是迄今为止识别它们的主要方式。JD1 之前被确定为一个三重成像星系,其放大倍数为 13,由前景星团 Abell 2744(参考文献3 )提供,光度红移为z ≈ 10。在这里,我们报告了在大爆炸后 480 Myr 观察到的这个极低光度 (≈0.05  L *) 星系在z  = 9.79 处的光谱确认,方法是识别莱曼断裂和红向连续体,以及多条 4 σ发射线,使用近红外光谱仪 (NIRSpec) 和近红外相机 (NIRCam) 仪器。詹姆斯·韦伯太空望远镜 (JWST) 和引力透镜的结合表明,这个超微弱星系 ( M UV  = −17.35)——具有负责宇宙再电离源的典型光度——具有紧凑的 (≈150 pc) 和复杂形态,低恒星质量(10 7.19 M⊙) 和次太阳 (≈0.6  Z⊙ )气相金属丰度。

更新日期:2023-05-18
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