On the Evolution of Supermassive Primordial Stars in Cosmological Flows

Author(s): Tyrone E. Woods, Samuel Patrick, Jacob S. Elford, Daniel Whalen, Alexander Heger
Abstract: Primordial supermassive stars (SMSs) formed in atomic-cooling halos at z ~ 15-20 are leading candidates for the seeds of the first quasars. Past numerical studies of the evolution of SMSs have typically assumed constant accretion rates rather than the highly variable flows in which they form. We model the evolution of SMSs in the cosmological flows that create them using the Kepler stellar evolution and implicit hydrodynamics code. We find that they reach masses of 1 - 2 × 10⁵ M_⊙ before undergoing direct collapse to black holes (DCBHs) during or at the end of their main-sequence hydrogen burning, at 1-1.5 Myr, regardless of halo mass, spin, or merger history. We also find that realistic, highly variable accretion histories allow for a much greater diversity of supermassive stellar structures, including in some cases largely thermally relaxed objects, which may provide a significant source of radiative feedback. Our models indicate that the accretion histories predicted for purely atomic-cooling halos may impose a narrow spectrum of masses on the seeds of the first massive quasars; however, further studies incorporating realistic feedback will be essential in order to confirm whether or not this holds true in all cases. Our results also indicate that multiple SMSs at disparate stages of evolution can form in these halos, raising the possibility of SMS binaries and supermassive X-ray binaries, as well as DCBH mergers that could be detected by LISA.
Organisation(s): Department of Astrophysics
External organisation(s): Herzberg Astronomy and Astrophysics Research Centre, Monash University, University of Portsmouth, OzGrav: the ARC Centre of Excellence for Gravitational-wave Discovery, ARC Centre of Excellence for All Sky Astrophysics in 3 Dimensions (ASTRO 3D), Michigan State University
Journal: The Astrophysical Journal
Volume: 915
No. of pages: 10
ISSN: 0004-637X
DOI: https://doi.org/10.3847/1538-4357/abfaf9
Publication date: 07-2021
Peer reviewed: Yes
Austrian Fields of Science 2012: 103003 Astronomy, 103004 Astrophysics, 103044 Cosmology
Keywords
ASJC Scopus subject areas: Astronomy and Astrophysics, Space and Planetary Science
Portal url: https://ucrisportal.univie.ac.at/en/publications/b994fff2-8719-45bb-9f47-8339f32653ef

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