Detailed study of stars and gas in a z = 8.3 massive merger with extreme dust conditions

Harshan, Anishya (author), Tripodi, Roberta (author), Martis, Nicholas S. (author), Rihtaršič, Gregor (author), Bradač, Maruša (author), Markov, Vladan (author)

We present galaxy MACS0416-Y1 at z$_{spec}$ = 8.312 as observed by the CAnadian NIRISS Unbiased Cluster Survey. MACS0416-Y1 has been shown to have extreme dust properties; thus, we study the physical properties and star formation histories of its resolved components. Overall, we find that MACS0416-Y1 is undergoing a star formation burst in three resolved clumps. The central clump is less massive compared to the other clumps and possibly formed in the merging process of the two larger clumps. Although the star formation history indicates an ongoing star formation burst, this gas-rich galaxy shows comparable star formation efficiency to cosmic noon galaxies. Using NIRSpec prism spectroscopy, we measure metallicity, 12 + log (O/H) = 7.76 ± 0.03, ionization parameter, log U = –2.48 ± 0.03, and electron temperature T$_e$ = 18000 ± 4000 K. The emission line ratios of the galaxy indicate an evolved interstellar medium similar to z ∼ 2 star-forming galaxies. Further, we find possible presence of ionization from an active galactic nucleus (AGN) using emission line diagnostics; however, we do not detect a broad-line component in the Hβ emission line. As this gas-rich galaxy is undergoing a major merger, we hypothesize that the high dust temperature in MACS0416-Y1 is caused by the star formation burst or a possible narrow-line AGN.

• Language: English
• Keywords: high-redshift galaxies, gravitational lensing, reionization, active galaxies, strong gravitational lensing
• Work type: Article
• Typology: 1.01 - Original Scientific Article
• Organization: FMF - Faculty of Mathematics and Physics
• Publication status: Published
• Publication version: Version of Record
• Year: 2024
• Number of pages: 9 str.
• Numbering: Vol. 977, no. 2, art. L36
• PID: 20.500.12556/RUL-166375
• UDC: 524.8
• ISSN on article: 2041-8213
• DOI: 10.3847/2041-8213/ad9741
• COBISS.SI-ID: 221495555
• Publication date in RUL: 09.01.2025

Record is a part of a journal

• Title: The Astrophysical journal. Letters
• Shortened title: Astrophys. J. Lett.
• Publisher: American Astronomical Society
• ISSN: 2041-8213
• COBISS.SI-ID: 367233

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.