Formation of a low-mass galaxy from star clusters in a 600-million-year-old universe

Mowla, Lamiya (author), Iyer, Kartheik G. (author), Asada, Yoshihisa (author), Martis, Nicholas S. (author), Bradač, Maruša (author), Rihtaršič, Gregor (author)

The most distant galaxies detected were seen when the Universe was a scant 5% of its current age. At these times, progenitors of galaxies such as the Milky Way were about 10,000 times less massive. Using the James Webb Space Telescope ( JWST) combined with magnification from gravitational lensing, these low-mass galaxies can not only be detected but also be studied in detail. Here we present JWST observations of a strongly lensed galaxy at zspec = 8.296 ± 0.001, showing massive star clusters (the Firefly Sparkle) cocooned in a diffuse arc in the Canadian Unbiased Cluster Survey (CANUCS)1. The Firefly Sparkle exhibits traits of a young, gas-rich galaxy in its early formation stage. The mass of the galaxy is concentrated in 10 star clusters (49–57% of total mass), with individual masses ranging from 105M⊙ to 106M⊙. These unresolved clusters have high surface densities (>103M⊙ pc−2), exceeding those of Milky Way globular clusters and young star clusters in nearby galaxies. The central cluster shows a nebular-dominated spectrum, low metallicity, high gas density and high electron temperature, hinting at a top-heavy initial mass function. These observations provide our first spectrophotometric view of a typical galaxy in its early stages, in a 600-million-year-old Universe.

• Language: English
• Keywords: gravitational lensing, early universe
• Work type: Article
• Typology: 1.01 - Original Scientific Article
• Organization: FMF - Faculty of Mathematics and Physics
• Publication version: Version of Record
• Publication date: 11.12.2024
• Year: 2024
• Number of pages: 5 str.
• Numbering: Vol. 636, issue 8042
• PID: 20.500.12556/RUL-165993
• UDC: 524
• ISSN on article: 0028-0836
• DOI: 10.1038/s41586-024-08293-0
• COBISS.SI-ID: 219301891
• Publication date in RUL: 16.12.2024

Record is a part of a journal

• Title: Nature : the international weekly journal of science
• Shortened title: Nature
• Publisher: Macmillan
• ISSN: 0028-0836
• COBISS.SI-ID: 1078026

Licences

• License: CC BY 4.0, Creative Commons Attribution 4.0 International
• Link: http://creativecommons.org/licenses/by/4.0/
• Description: This is the standard Creative Commons license that gives others maximum freedom to do what they want with the work as long as they credit the author.

Secondary language

• Language: Slovenian
• Keywords: gravitacijsko lečenje, zgodnje vesolje