FORMATION OF PRIMORDIAL SUPERMASSIVE STARS BY RAPID MASS ACCRETION

By T. Hosokawa, H. Yorke, K. Inayoshi, K. Omukai, Naoki Yoshida. 2013

172 citations recorded by the source corpus.

Supermassive stars (SMSs) forming via very rapid mass accretion () could be precursors of supermassive black holes observed beyond a redshift of about six. Extending our previous work, here we study the evolution of primordial stars growing under such rapid mass accretion until the stellar mass reaches 104 − 5 M☉. Our stellar evolution calculations show that a star becomes supermassive while passing through the “supergiant protostar” stage, whereby the star has a very bloated envelope and a contracting inner core. The stellar radius increases monotonically with the stellar mass until ≃ 100 AU for M* ≳ 104 M☉, after which the star begins to slowly contract. Because of the large radius, the effective temperature is always less than 104 K during rapid accretion. The accreting material is thus almost completely transparent to the stellar radiation. Only for M* ≳ 105 M☉ can stellar UV feedback operate and disturb the mass accretion flow. We also examine the pulsation stability of accreting SMSs, showing that the pulsation-driven mass loss does not prevent stellar mass growth. Observational signatures of bloated SMSs should be detectable with future observational facilities such as the James Webb Space Telescope. Our results predict that an inner core of the accreting SMS should suffer from the general relativistic instability soon after the stellar mass exceeds 105 M☉. An extremely massive black hole should form after the collapse of the inner core.

Subfields: Astronomy and Astrophysics, Instrumentation

View Paper: https://www.semanticscholar.org/paper/d6296ceb902ed5ac9dc24d8619d16be1d8627440

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Citations in the corpus

Near-Field Cosmology with Extremely Metal-Poor Stars (2015, background): “Hosokawa et al. (2013) simulated Population III stars with masses of 104−5 M⊙ which are expected to collapse directly into a supermassive black hole.”
The Romulus cosmological simulations: a physical approach to the formation, dynamics and accretion models of SMBHs (2016, background): “…motivated by the fact that much of the early growth onto SMBH seeds, or the exotic objects that may proceed them, can exceed 0.1 M yr−1 and be governed by the environment and physical processes well below the resolu- tion limit of our simulations (e.g. Hosokawa et al. 2013; Schleicher et al. 2013).”
Building up the Population III initial mass function from cosmological initial conditions (2016, background): “Furthermore, even with disc accretion some amount of entropy may still be advected into the star, particularly for rapid accretion rates (e.g. Hosokawa et al. 2013).”
Titans of the early Universe: The Prato statement on the origin of the first supermassive black holes (2018, background): “The onlymechanism allowing formass-loss is pulsational instability (Inayoshi, Hosokawa, & Omukai 2013; Hosokawa et al. 2013).”
Hyper-Eddington accretion flows on to massive black holes (2015, background): “…would be also inefficient because the star has a bloated cold envelope with ∼ 5000 K and directly collapses to a BH without mass-loss and explosions (Hosokawa, Omukai & Yorke 2012; Inayoshi, Hosokawa & Omukai 2013; Hosokawa et al. 2013; Schleicher et al. 2013, but see also Chen et al. 2014).”
FORMATION OF MASSIVE PRIMORDIAL STARS: INTERMITTENT UV FEEDBACK WITH EPISODIC MASS ACCRETION (2015, background): “Stellar evolution calculations which include the effects of mass accretion show that rapid accretion with Ṁ∗ & 10−2 M yr−1 dramatically changes the protostellar structure, causing the abrupt expansion of the star (e.g., Hosokawa et al. 2012a, 2013; Schleicher et al. 2013).”
ONE HUNDRED FIRST STARS: PROTOSTELLAR EVOLUTION AND THE FINAL MASSES (2013, background): “We argue that rapid mass accretion is a promising path for forming very massive (& 103 M⊙) stars in the early universe (see e.g. Hosokawa et al. 2012a, 2013).”
Formation of Supermassive Black Hole Seeds (2016, background): “The key requirement for this scenario is to have large gas accretion rates of ≥ 0.1 M⊙/yr (Hosokawa et al. 2013; Schleicher et al. 2013).”
Unveiling the gravitational universe at μ-Hz frequencies (2019, background): “Some of the models involve the formation of supermassive protostars/stars (M > 10(5) M⊙) which later collapse into a BH once hydrostatic equilibrium cannot be maintained any longer or once the pulsational relativistic radial instability sets in [127, 138].”