The rate and contribution of mergers to mass assembly from NIRCam observations of galaxy candidates up to 13.3 billion years ago

Dalmasso, Nicolò (author), Calabrò, Antonello (author), Leethochawalit, Nicha (author), Bradač, Maruša (author)

We present an analysis of the galaxy merger rate in the redshift range 4.0 < z < 9.0 (i.e. about 1.5 to 0.5 Gyr after the big bang) based on visually identified galaxy mergers from morphological parameter analysis. Our data set is based on high-resolution NIRCam JWST data (a combination of F150W and F2000W broad-band filters) in the low-to-moderate magnification (μ < 2) regions of the Abell 2744 cluster field. From a parent set of 675 galaxies (MU ∈ [−26.6, −17.9]), we identify 64 merger candidates from the Gini, M20 and asymmetry morphological parameters, leading to a merger fraction fm = 0.11 ± 0.04. There is no evidence of redshift evolution of fm even at the highest redshift considered, thus extending well into the epoch of reionization the constant trend seen previously at z < 6. Furthermore, we investigate any potential redshift-dependent differences in the specific star formation rates between mergers and non-mergers. Our analysis reveals no significant correlation in this regard, with deviations in the studied redshift range typically falling within (1 − 1.5)σ from the null hypothesis that can be attributed to sample variance and measurement errors. Finally, we also demonstrate that the classification of a merging system is robust with respect to the observed (and equivalently rest frame) wavelength of the high-quality JWST broad-band images used. This preliminary study highlights the potential for progress in quantifying galaxy assembly through mergers during the epoch of reionization, with significant sample size growth expected from upcoming large JWST infrared imaging data sets.

• Language: English
• Keywords: galaxies formation, star formation, high-redshift galaxies
• 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: 13 str.
• Numbering: Vol. 533, iss. 4
• PID: 20.500.12556/RUL-162514
• UDC: 524.8
• ISSN on article: 1365-2966
• DOI: 10.1093/mnras/stae2064
• COBISS.SI-ID: 208384259
• Publication date in RUL: 24.09.2024

Record is a part of a journal

• Title: Monthly notices of the Royal Astronomical Society
• Shortened title: Mon. not. R. Astron. Soc.
• Publisher: Blackwell Science
• ISSN: 1365-2966
• COBISS.SI-ID: 1870180

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.