Disc fragmentation and intermittent accretion on to supermassive stars

Author(s): Ryoki Matsukoba, Eduard Vorobiev, Kazuyuki Sugimura, Sunmyon Chon, Takashi Hosokawa, Kazuyuki Omukai
Abstract: Supermassive stars (SMSs) with ∼10⁴-10⁵ M_⊙ are candidate objects for the origin of supermassive black holes observed at redshift z > 6. They are supposed to form in primordial-gas clouds that provide the central stars with gas at a high accretion rate, but their growth may be terminated in the middle due to the stellar ionizing radiation if the accretion is intermittent and its quiescent periods are longer than the Kelvin-Helmholtz (KH) time-scales at the stellar surfaces. In this paper, we examine the role of the ionizing radiation feedback based on the accretion history in two possible SMS-forming clouds extracted from cosmological simulations, following their evolution with vertically integrated two-dimensional hydrodynamic simulations with detailed thermal and chemical models. The consistent treatment of the gas thermal evolution is crucial for obtaining the realistic accretion history, as we demonstrate by performing an additional run with a barotropic equation of state, in which the fluctuation of the accretion rate is artificially suppressed. We find that although the accretion becomes intermittent due to the formation of spiral arms and clumps in gravitationally unstable discs, the quiescent periods are always shorter than the KH time-scales, implying that SMSs can form without affected by the ionizing radiation.
Organisation(s): Department of Astrophysics
External organisation(s): Tohoku University, University of Maryland, College Park, Kyoto University
Journal: Monthly Notices of the Royal Astronomical Society
Volume: 500
Pages: 4126-4138
No. of pages: 13
ISSN: 0035-8711
DOI: https://doi.org/10.1093/mnras/staa3462
Publication date: 01-2021
Peer reviewed: Yes
Austrian Fields of Science 2012: 103003 Astronomy, 103004 Astrophysics
Keywords
ASJC Scopus subject areas: Astronomy and Astrophysics, Space and Planetary Science
Portal url: https://ucrisportal.univie.ac.at/en/publications/c2a28fe8-806f-4ff9-8baf-7b1201a83b91

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