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DRAGON-III simulation: modelling million-body globular and nuclear star clusters

Kai Wu, Philip Cho, Rainer Spurzem, Long Wang, Francesco Flammini Dotti, Vahid Amiri

TL;DR

DRAGON-III expands the DRAGON project to million-body globular and nuclear star clusters, simulating their dynamics over a 10 Gyr timescale with realistic binary populations and escaping-star tracking. It uses NBODY6++GPU with NewSSE, integrates MWPotential2014 for Galactic tides, and includes a HIP port for AMD/NVIDIA HPC to enable cross-architecture runs. Initial conditions cover 1M, 4M, and 10M stars with varied soft-binary fractions and NSC runs with an accreting central SMBH. Early results after ~100 Myr reveal a rich multi-messenger landscape, including 41 pulsars, 191 X-ray binaries, 17 gravitational-wave sources, and a BH-BH merger, plus notable systems such as an IMBH in a wide BH-BH binary and a BH-MS binary near Gaia-BH1-like systems, underscoring the potential for observational counterparts across electromagnetic, gravitational-wave, and X-ray channels.

Abstract

As a continuation of DRAGON-II, we present the DRAGON-III project, which focuses on the simulations of million-body globular clusters and nuclear clusters over 10 Gyr. We report on its preliminary results on globular clusters. The first 100 Myr of the simulations have produced 41 pulsars, 191 X-ray binaries, 17 gravitational wave sources, and one black hole-black hole merger due to the loss of orbital energy in the form of gravitational wave emission. The inclusion of initial soft binaries brings surprisingly interesting results, including one IMBH in a binary black hole, and compact object binaries resembling the Gaia-BH1 and the wide black hole-giant binary reported in Wang et al. (2024, Nat. Astro.).

DRAGON-III simulation: modelling million-body globular and nuclear star clusters

TL;DR

DRAGON-III expands the DRAGON project to million-body globular and nuclear star clusters, simulating their dynamics over a 10 Gyr timescale with realistic binary populations and escaping-star tracking. It uses NBODY6++GPU with NewSSE, integrates MWPotential2014 for Galactic tides, and includes a HIP port for AMD/NVIDIA HPC to enable cross-architecture runs. Initial conditions cover 1M, 4M, and 10M stars with varied soft-binary fractions and NSC runs with an accreting central SMBH. Early results after ~100 Myr reveal a rich multi-messenger landscape, including 41 pulsars, 191 X-ray binaries, 17 gravitational-wave sources, and a BH-BH merger, plus notable systems such as an IMBH in a wide BH-BH binary and a BH-MS binary near Gaia-BH1-like systems, underscoring the potential for observational counterparts across electromagnetic, gravitational-wave, and X-ray channels.

Abstract

As a continuation of DRAGON-II, we present the DRAGON-III project, which focuses on the simulations of million-body globular clusters and nuclear clusters over 10 Gyr. We report on its preliminary results on globular clusters. The first 100 Myr of the simulations have produced 41 pulsars, 191 X-ray binaries, 17 gravitational wave sources, and one black hole-black hole merger due to the loss of orbital energy in the form of gravitational wave emission. The inclusion of initial soft binaries brings surprisingly interesting results, including one IMBH in a binary black hole, and compact object binaries resembling the Gaia-BH1 and the wide black hole-giant binary reported in Wang et al. (2024, Nat. Astro.).

Paper Structure

This paper contains 7 sections, 1 figure, 2 tables.

Table of Contents

  1. Introduction
  2. Multi-messenger astrophysics of globular and nuclear star clusters
  3. The DRAGON simulation family
  4. Numerical methods
  5. Code
  6. Initial conditions
  7. Selected preliminary results

Figures (1)

  • Figure 1: Semi-major axis as a function of primary mass for binaries with at least one compact object component, in the simulation with 20% initial soft binary after evolving for 84.16 Myr, which equals 3749 initial crossing time, and 0.5 initial half-mass relaxation time. In the bottom left corner is the count of binaries by stellar types of their components. Meaning of the stellar type abbreviation in this table and in the legend can be found in hurley2000-sse. Meaning of marker style: square - black hole as primary star, octagon - neutron star as primary star, pentagon - white dwarf as primary star.