The survival of star clusters with black hole subsystems

Abstract

Recent observations have detected top-heavy IMFs in dense star forming regions like the Arches cluster. Whether such IMFs also exist in old dense stellar systems like globular clusters is difficult to constrain, because massive stars already became black holes (BHs) and neutron stars (NSs). However, studies of stellar dynamics find that BHs/NSs influence the long-term evolution of star clusters. Following Breen & Heggie (2013) and by carrying out two-component $N$-body simulations, we demonstrate how this dynamical impact connects with the shape of IMFs. By investigating the energy balance between the BH subsystem and the global, we find that to properly describe the evolution of clusters, a corrected two-body relaxation time, $T_{rh,p}=T_{rh}/\psi$, is necessary. Because $\psi$ depends on the total mass fraction of BHs, $M_2/M$, and the mass ratio, $m_2/m_1$, the cluster dissolution time is sensitive to the property of BHs or IMFs. Especially, the escape rate of BHs via ejections from few-body encounters is linked to mass segregation. In strong tidal fields, top-heavy IMFs easily lead to the fast dissolution of star clusters and the formation of BH-dominant dark clusters, which suggests that the observed massive GCs with dense cores are unlikely to have extreme top-heavy IMFs. With the future observations of gravitational waves providing unique information of BHs/NSs, it is possible to combine the multi-message observations to have better constrains on the IMFs of old star clusters.

12 pages, 13 figures, accepted for MNRAS

References in corpus (3)

• An excess of massive stars in the local 30 Doradus starburst
• Mergers of Stellar-Mass Black Holes in Nuclear Star Clusters
• The Global Mass Functions of 35 Galactic globular clusters: II. Clues on the Initial Mass Function and Black Hole Retention Fraction

Cited by in corpus (14)

• The Physics of Star Cluster Formation and Evolution
• Very high redshift quasars and the rapid emergence of super-massive black holes
• Compact object mergers: exploring uncertainties from stellar and binary evolution with SEVN
• A slow-down time-transformed symplectic integrator for solving the few-body problem
• Black Hole Mergers from Star Clusters with Top-Heavy Initial Mass Functions
• The mass-loss rates of star clusters with stellar-mass black holes: implications for the globular cluster mass function
• The dynamics of the globular cluster NGC3201 out to the Jacobi radius
• The impact of primordial binary on the dynamical evolution of intermediate massive star clusters
• Impact of initial mass functions on the dynamical channel of gravitational wave sources
• Discovery and Timing of Millisecond Pulsars in the Globular Cluster M5 (NGC 5904) with FAST and Arecibo
• On the origin of the split main sequences of the young massive cluster NGC 1856
• Dark Star Clusters or Ultra-Faint Dwarf galaxies? Revisiting UMa3/U1
• Origin of High Dark Remnant Fractions in Milky Way Globular Clusters: The Crucial Role of Initial Black Hole Retention
• Stellar population modelling of neutron stars and black holes: spatially-resolved graveyards in MaNGA/SDSS-IV galaxies