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

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Main Authors: Dalmasso, Nicolò, Calabrò, Antonello, Leethochawalit, Nicha, Vulcani, Benedetta, Boyett, Kristan, Trenti, Michele, Treu, Tommaso, Castellano, Marco, Bradač, Maruša, Metha, Benjamin, Santini, Paola
Format: Preprint
Published: 2024
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author Dalmasso, Nicolò
Calabrò, Antonello
Leethochawalit, Nicha
Vulcani, Benedetta
Boyett, Kristan
Trenti, Michele
Treu, Tommaso
Castellano, Marco
Bradač, Maruša
Metha, Benjamin
Santini, Paola
author_facet Dalmasso, Nicolò
Calabrò, Antonello
Leethochawalit, Nicha
Vulcani, Benedetta
Boyett, Kristan
Trenti, Michele
Treu, Tommaso
Castellano, Marco
Bradač, Maruša
Metha, Benjamin
Santini, Paola
contents 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 dataset is based on high-resolution NIRCam JWST data (a combination of F150W and F200W 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 $(M_{U}\in[-26.6,-17.9])$, we identify 64 merger candidates from the Gini, $M_{20}$ and Asymmetry morphological parameters, leading to a merger fraction $f_m=0.11\pm0.04$. There is no evidence of redshift evolution of $f_m$ even at the highest redshift considered, thus extending well into the epoch of reionization the constant trend seen previously at $z\lesssim 6$. 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 hypotesis 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 datasets.
format Preprint
id arxiv_https___arxiv_org_abs_2403_11428
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle The rate and contribution of mergers to mass assembly from NIRCam observations of galaxy candidates up to 13.3 billion years ago
Dalmasso, Nicolò
Calabrò, Antonello
Leethochawalit, Nicha
Vulcani, Benedetta
Boyett, Kristan
Trenti, Michele
Treu, Tommaso
Castellano, Marco
Bradač, Maruša
Metha, Benjamin
Santini, Paola
Astrophysics of Galaxies
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 dataset is based on high-resolution NIRCam JWST data (a combination of F150W and F200W 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 $(M_{U}\in[-26.6,-17.9])$, we identify 64 merger candidates from the Gini, $M_{20}$ and Asymmetry morphological parameters, leading to a merger fraction $f_m=0.11\pm0.04$. There is no evidence of redshift evolution of $f_m$ even at the highest redshift considered, thus extending well into the epoch of reionization the constant trend seen previously at $z\lesssim 6$. 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 hypotesis 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 datasets.
title The rate and contribution of mergers to mass assembly from NIRCam observations of galaxy candidates up to 13.3 billion years ago
topic Astrophysics of Galaxies
url https://arxiv.org/abs/2403.11428