Effect of mass-loss due to stellar winds on the formation of supermassive black hole seeds in dense nuclear star clusters

Journal article

The observations of high-redshifts quasars at z ≳ 6 have revealed that supermassive black holes (SMBHs) of mass ∼109M⊙∼109M⊙ were already in place within the first ∼Gyr after the big bang. Supermassive stars (SMSs) with masses 103−5M⊙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 idealized 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,and0.9fEdd=L∗/LEdd=0.5,0.7,and0.9⁠. For a high accretion rate of 10−4M⊙yr−110−4M⊙yr−1⁠, SMSs with masses ≳103M⊙yr−1≳103M⊙yr−1 could be formed even in a high metallicity environment. For a lower accretion rate of 10−5M⊙yr−110−5M⊙yr−1⁠, SMSs of masses ∼103−4M⊙∼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⊙∼103M⊙ can be formed in low metallicity environments with Z* ≲ 0.01 Z⊙. The most massive SMSs of masses ∼105M⊙∼105M⊙ can be formed for Bondi–Hoyle accretion in environments with Z* ≲ 0.5 Z⊙. 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.

Authors: Das, A; Schleicher, DRG; Basu, S; Boekholt, TCN

• Publication status: Published
• Peer review status: Peer reviewed
• Publisher: Oxford University Press
• Journal: Monthly Notices of the Royal Astronomical Society
• Volume: 505
• Issue: 2
• Pages: 2186-2194
• Publication date: 2021-05-19
• Acceptance date: 2021-05-13
• DOI: 10.1093/mnras/stab1428
• EISSN: 1365-2966
• ISSN: 0035-8711
• Language: English
• Keywords: black hole physics; FFR; galaxies: high-redshift