Interaction-induced star formation boosts stellar mass assembly in z∼5 galaxies

@misc{omori2026interactioninduced,
  title = {{Interaction-induced star formation boosts stellar mass assembly in $z\sim5$ galaxies}},
  author = {Kiyoaki C. Omori and Marcin Sawicki and Rosa M. Mérida and Guillaume Desprez and Roberto Abraham and Maruša Bradač and Nicholas S. Martis and Adam Muzzin and Gaël Noirot and Ghassan T. Sarrouh and Christopher J. Willott and Danilo Marchesini and Katherine Myers},
  howpublished = {arXiv},
  year = {2026},
  month = oct,
  doi = {10.48550/arxiv.2606.28590},
  eprint = {2606.28590},
  archivePrefix = {arXiv},
  url = {https://arxiv.org/abs/2606.28590},
  note = {CC BY 4.0},
}

TY  - UNPB
TI  - Interaction-induced star formation boosts stellar mass assembly in z∼5 galaxies
AU  - Kiyoaki C. Omori
AU  - Marcin Sawicki
AU  - Rosa M. Mérida
AU  - Guillaume Desprez
AU  - Roberto Abraham
AU  - Maruša Bradač
AU  - Nicholas S. Martis
AU  - Adam Muzzin
AU  - Gaël Noirot
AU  - Ghassan T. Sarrouh
AU  - Christopher J. Willott
AU  - Danilo Marchesini
AU  - Katherine Myers
PY  - 2026
DA  - 2026/10/30
PB  - arXiv
DO  - 10.48550/arxiv.2606.28590
UR  - https://arxiv.org/abs/2606.28590
AB  - Galaxy interactions are a key ingredient in galaxy evolution; not only are they a primary pathway of galaxy growth and mass assembly, but also a key driver of processes such as star formation and quenching. We investigate the impact of galaxy-galaxy interactions on stellar mass assembly using JWST/NIRCam observations of a spectroscopically selected sample of galaxies at 5.0<z_spec<5.6 from the Canadian NIRISS Unbiased Cluster Survey (CANUCS). Of the 48 galaxies in our parent sample, we visually classify 21 (44%) as closely-interacting (≲~5~kpc) system {candidates} with two or more components. We evaluate the non-parametric star formation histories (SFHs) of these systems' components using the spectral energy distribution fitting code \textsc{Dense Basis}. We find that the components in these systems experience brief intervals (∼0.2 Gyr) of strongly enhanced star formation that grow their stellar mass by ∼2.66±0.85×, forming ∼1.58±0.25× of excess mass than expected compared to if there was no burst. Attributing these star formation rate enhancements to interactions and assuming that the components will merge, we find that mergers are responsible for ∼38^+18_−20% of the total stellar mass growth of galaxies at z∼5. While {there is significant} contribution {to mass growth} from the merging of the pre-existing stellar masses of the merging galaxies, {up to }half {is} due to stellar mass that is newly-formed during the interaction. We conclude that mergers, and their associated star formation bursts, are an important pathway for stellar mass growth in high-z galaxies.
ER  -