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arXiv · 2601.02506

Star Formation in Galaxy Collisions: Dependence on Impact Velocity and Gas Mass of Galaxies in GADGET-4 Simulations

Gustavo Neves Pereira·Paulo Laerte Natti
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Abstract

This work investigates variations in the star formation rate during galaxy collisions when the initial conditions of velocity and gas mass are altered. For this purpose, hydrodynamic simulations were performed using the GADGET-4 code, with initial conditions generated by the Galstep and SnapshotJoiner programs. Systems of two galaxies on a head-on collision course were modeled with relative initial velocities ranging from 100 km/s to 1000 km/s, considering two scenarios: the first with identical galaxies, and the second with galaxies of different sizes. In simulations of systems with higher initial relative velocities, both found more intense peaks in the star formation rate, triggered by the first contact of the collision, followed by a strong decline caused by gas dispersion. In contrast, for systems with lower initial velocities, mergers between galaxies were observed, leading to multiple peaks in the star formation rate. A greater initial distance between galaxies has also been linked to whether or not the galaxy system merges, since it implies longer timescales for gravitational action, which leads to higher relative velocities at the moment of collision. Furthermore, the star formation rate in galaxies was found to have a clear dependence on initial gas content. Furthermore, the initial gas content in galaxies was found to have a clear dependence on star formation rates. Overall, our results show that the relative impact velocity, the initial distance between the galaxies, and the gas content are important parameters for analyzing the star formation rate in colliding galaxies.

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Gustavo Neves Pereira, Paulo Laerte Natti. 2026-01-05. Star Formation in Galaxy Collisions: Dependence on Impact Velocity and Gas Mass of Galaxies in GADGET-4 Simulations. https://arxiv.org/abs/2601.02506

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