# The Subtle Effects of Mergers on Star Formation in Nearby Galaxies

**Authors:** Yang A. Li, Luis C. Ho, Jinyi Shangguan  
**arXiv:** [2307.13462](https://arxiv.org/abs/2307.13462)  
**Date:** 2023-07-25  
**Summary page:** https://www.summarizepaper.com/en/paper/2307.13462v1/

## Key points

- Study focuses on the role of interactions and mergers in regulating physical properties of galaxies
- Investigates merger pairs from a sample of massive galaxies in the Sloan Digital Sky Survey
- Uses panchromatic photometry and spectral energy distribution analysis to derive stellar masses, SFRs, and total dust masses
- Measurements reveal bimodal distribution on the M_gas-M_* plane: gas-rich, star-forming galaxies and passive, gas-poor galaxies
- Bimodal distribution also observed when considering relationship between SFR and gas mass surface density
- Mergers have minimal effects on SFRs or specific SFRs, even for gas-rich or nearly equal-mass systems
- Starbursts are rare; even minor mergers involving gas-rich galaxies suppress star formation efficiency
- Complex factors influence evolution of gas and its ability to form stars during galaxy mergers
- Interactions and mergers may not significantly enhance star formation activity in low-redshift galaxies

## Summary

This study focuses on the role of interactions and mergers in regulating the physical properties of galaxies, such as their morphology, gas content, and star formation rate (SFR). The authors investigate merger pairs from a sample of massive galaxies with stellar masses greater than or equal to $10^{10}$ solar masses, located in the Stripe 82 region of the Sloan Digital Sky Survey. They use panchromatic photometry and spectral energy distribution analysis to derive stellar masses, SFRs, and total dust masses. By converting the dust masses to equivalent total atomic and molecular hydrogen, the authors are able to probe gas masses as low as approximately $10^{8.5}$ solar masses. Their measurements reveal a bimodal distribution on the $M_{\text{gas}}-M_*$ plane: one group consists of gas-rich, star-forming galaxies that follow the well-studied gas mass main sequence, while the other group comprises passive galaxies in a distinct, gas-poor regime. These two populations also exhibit a bimodal distribution when considering the relationship between SFR and gas mass surface density. The study specifically examines the impact of galaxy mergers on low-redshift galaxies, including those involving gas-rich and nearly equal-mass systems. Surprisingly, they find that these mergers have minimal effects on SFRs or specific SFRs (SFR per unit stellar mass), or star formation efficiency. Starbursts are rare in this context; even minor mergers involving gas-rich galaxies appear to suppress star formation efficiency. Overall, this research highlights how complex factors influence the evolution of gas and its ability to form stars during galaxy mergers. The findings suggest that interactions and mergers may not significantly enhance star formation activity in low-redshift galaxies. This expanded summary provides additional context for understanding how mergers impact nearby galaxies' star formation processes.