Archive | 2021
Effect of mass-loss due to stellar winds on the formation of supermassive black hole seeds in dense nuclear star clusters
Abstract
The observations of high redshifts quasars at z & 6 have revealed that supermassive black holes (SMBHs) of mass∼ 109M were already in place within the first ∼ Gyr after the Big Bang. Supermassive stars (SMSs) with masses 103−5M are potential seeds for these observed SMBHs. A possible formation channel of these SMSs is the interplay of gas accretion and runaway stellar collisions inside dense nuclear star clusters (NSCs). However, mass loss due to stellar winds could be an important limitation for the formation of the SMSs and affect the final mass. In this paper, we study the effect of mass loss driven by stellar winds on the formation and evolution of SMSs in dense NSCs using idealised N-body simulations. Considering different accretion scenarios, we have studied the effect of the mass loss rates over a wide range of metallicities Z∗ = [.001 − 1]Z and Eddington factors fEdd = L∗/LEdd = 0.5, 0.7, &0.9. For a high accretion rate of 10−4M yr−1, SMSs with masses & 103M could be formed even in a high metallicity environment. For a lower accretion rate of 10−5M yr−1, SMSs of masses ∼ 103−4M can be formed for all adopted values of Z∗ and fEdd, except for Z∗ = Z and fEdd = 0.7 or 0.9. For Eddington accretion, SMSs of masses ∼ 103M can be formed in low metallicity environments with Z∗ . 0.01Z . The most massive SMSs of masses ∼ 105M can be formed for Bondi-Hoyle accretion in environments with Z∗ . 0.5Z . An intermediate regime is likely to exist where the mass loss from the winds might no longer be relevant, while the kinetic energy deposition from the wind could still inhibit the formation of a very massive object.