Introducing a new multi-particle collision method for the evolution of dense stellar systems: Crash-test N -body simulations

Pierfrancesco Di Cintio, Mario Pasquato, Hyunwoo Kim, Suk Jin Yoon

Research output: Contribution to journalArticlepeer-review

Abstract

Context. Stellar systems are broadly divided into collisional and non-collisional categories. While the latter are large-N systems with long relaxation timescales and can be simulated disregarding two-body interactions, either computationally expensive direct N-body simulations or approximate schemes are required to properly model the former. Large globular clusters and nuclear star clusters, with relaxation timescales of the order of a Hubble time, are small enough to display some collisional behaviour and big enough to be impossible to simulate with direct N-body codes and current hardware. Aims. We aim to introduce a new method to simulate collisional stellar systems and validate it by comparison with direct N-body codes on small-N simulations. Methods. The Multi-Particle Collision for Dense Stellar Systems (MPCDSS) code is a new code for evolving stellar systems with the multi-particle collision method. Such a method amounts to a stochastic collision rule that makes it possible to conserve the exact energy and momentum over a cluster of particles experiencing the collision. The code complexity scales with N log N in the number of particles. Unlike Monte Carlo codes, MPCDSS can easily model asymmetric, non-homogeneous, unrelaxed, and rotating systems, while allowing us to follow the orbits of individual stars. Results. We evolved small (N  =  3.2  ×  104) star clusters with MPCDSS and with the direct-summation code NBODY6, finding a similar evolution of key indicators. We then simulated different initial conditions in the 104  -  106 star range. Conclusions. MPCDSS bridges the gap between small collisional systems that can be simulated with direct N-body codes and large non-collisional systems. In principle, MPCDSS allows us to simulate globular clusters such as ω Centauri and M 54, and even nuclear star clusters, which is beyond the limits of current direct N-body codes in terms of the number of particles.

Original languageEnglish
Article numberA24
JournalAstronomy and Astrophysics
Volume649
DOIs
Publication statusPublished - 2021 May 1

Bibliographical note

Funding Information:
Acknowledgements. This project has received funding from the European Union’s Horizon 2020 research and innovation program under the Marie Skłodowska-Curie grant agreement No. 664931. This material is based upon work supported by Tamkeen under the NYU Abu Dhabi Research Institute grant CAP3. P.F.D.C. wishes to thank the financing from MIUR-PRIN2017 project Coarse-grained description for non-equilibrium systems and transport phenomena (CO-NEST) n.201798CZL. S.-J.Y. acknowledges support by the Mid-career Researcher Program (No. 2019R1A2C3006242) through the National Research Foundation of Korea. We thank, A. A. Trani, L. Ciotti, and G. Ciraolo for the discussions at an early stage of this project, and the anonymous Referee for his/her comments that helped improving the presentation of this work.

Funding Information:
This project has received funding from the European Union?s Horizon 2020 research and innovation program under the Marie Sklodowska-Curie grant agreement No. 664931. This material is based upon work supported by Tamkeen under the NYU Abu Dhabi Research Institute grant CAP3. P.F.D.C. wishes to thank the financing from MIUR-PRIN2017 project Coarse-grained description for non-equilibrium systems and transport phenomena (CO-NEST) n.201798CZL. S.-J.Y. acknowledges support by the Mid-career Researcher Program (No. 2019R1A2C3006242) through the National Research Foundation of Korea.

Publisher Copyright:
© ESO 2021.

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science

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