| Issue |
A&A
Volume 659, March 2022
|
|
|---|---|---|
| Article Number | A19 | |
| Number of page(s) | 8 | |
| Section | Galactic structure, stellar clusters and populations | |
| DOI | https://doi.org/10.1051/0004-6361/202140710 | |
| Published online | 28 February 2022 | |
Introducing a new multi-particle collision method for the evolution of dense stellar systems
II. Core collapse
1
Dipartimento di Fisica e Astronomia & CSDC, Università di Firenze, Via G. Sansone 1, 50019 Sesto Fiorentino, Italy
e-mail: pierfrancesco.dicintio@unifi.it, alicia.simonpetit@unifi.it
2
INFN – Sezione di Firenze, Via G. Sansone 1, 50019 Sesto Fiorentino, Italy
3
CREF, Via Panisperna 89A, 00184 Rome, Italy
4
Center for Astro, Particle and Planetary Physics (CAP 3), New York University, Abu Dhabi, UAE
e-mail: mp5757@nyu.edu
5
Department of Astronomy and Center for Galaxy Evolution Research, Yonsei University, Seoul 120-749, Republic of Korea
Received:
3
March
2021
Accepted:
14
June
2021
Context. In a previous paper we introduced a new method for simulating collisional gravitational N-body systems with linear time scaling on N, based on the multi-particle collision (MPC) approach. This allows us to easily simulate globular clusters with a realistic number of stellar particles (105 − 106) in a matter of hours on a typical workstation.
Aims. We evolve star clusters containing up to 106 stars to core collapse and beyond. We quantify several aspects of core collapse over multiple realizations and different parameters while always resolving the cluster core with a realistic number of particles.
Methods. We run a large set of N-body simulations with our new code MPCDSS. The cluster mass function is a pure power law with no stellar evolution, allowing us to clearly measure the effects of the mass spectrum on core collapse.
Results. Leading up to core collapse, we find a power-law relation between the size of the core and the time left to core collapse. Our simulations thus confirm the theoretical self-similar contraction picture but with a dependence on the slope of the mass function. The time of core collapse has a non-monotonic dependence on the slope, which is well fitted by a parabola. This also holds for the depth of core collapse and for the dynamical friction timescale of heavy particles. Cluster density profiles at core collapse show a broken-power-law structure, suggesting that central cusps are a genuine feature of collapsed cores. The core bounces back after collapse, with visible fluctuations, and the inner density slope evolves to an asymptotic value. The presence of an intermediate-mass black hole inhibits core collapse, making it much shallower, irrespective of the mass-function slope.
Conclusions. We confirm and expand on several predictions of star cluster evolution before, during, and after core collapse. Such predictions were based on theoretical calculations or small-size direct N-body simulations. Here we put them to the test in MPC simulations with a much larger number of particles, allowing us to resolve the collapsing core.
Key words: globular clusters: general / methods: numerical
© ESO 2022
Current usage metrics show cumulative count of Article Views (full-text article views including HTML views, PDF and ePub downloads, according to the available data) and Abstracts Views on Vision4Press platform.
Data correspond to usage on the plateform after 2015. The current usage metrics is available 48-96 hours after online publication and is updated daily on week days.
Initial download of the metrics may take a while.