2023/07/10 by Manuel Arca Sedda, Sedda, Manuel Arca, Albrecht Kamlah +17 · 4 citations
Physics and Astronomy · #Astronomy and Astrophysical Research #Astrophysical Phenomena and Observations #Astrophysics of Galaxies (astro-ph.GA) #FOS: Physical sciences #Stellar, planetary, and galactic studies
paper · pdf · doi:10.48550/arxiv.2307.04805
openalex publication_date 2023/07/10 · openalex created_date 2023/07/13 · openalex updated_date 2026/07/30
We present the first results of the Dragon-II simulations, a suite of 19 N-body simulations of star clusters with up to 106 stars, with up to 33% of them initially paired in binaries. In this work, we describe the main evolution of the clusters and their compact objects (COs). All Dragon-II clusters form in their centre a black hole (BH) subsystem with a density 10-100 times larger than the stellar density, with the cluster core containing 50-80% of the whole BH population. In all models, the BH average mass steeply decreases as a consequence of BH burning, reaching values ⟨ m\rm BH⟩ < 15 M_\odot within 10-30 relaxation times. Generally, our clusters retain only BHs lighter than 30 M_\odot over 30 relaxation times. Looser clusters retain a higher binary fraction, because in such environments binaries are less likely disrupted by dynamical encounters. We find that BH-main sequence star binaries have properties similar to recently observed systems. Double CO binaries (DCOBs) ejected from the cluster exhibit larger mass ratios and heavier primary masses than ejected binaries hosting a single CO (SCOBs). Ejected SCOBs have BH masses m\rm BH = 3-20 M_\odot, definitely lower than those in DCOBs (m\rm BH = 10-100 M_\odot).