Establishing a reliable determination of the final mass for rapidly accreting supermassive stars
Abstract
Context. The formation of supermassive black holes possibly takes place via direct collapse, with a supermassive star (SMS) as its progenitor. In this scenario, the SMS accretes at > 0.1 M⊙ yr-1 until it collapses into a massive black hole seed as a result of the general-relativistic (GR) instability. However, the exact mass at which the collapse occurs is not known, as existing numerical simulations give us a divergent range of results.
Aims: Here, we address this problem analytically, which allows for reliable ab initio determination of the onset point of the GR instability, for given hydrostatic structures.
Methods: We applied the relativistic equation of radial pulsations in its general form to the hydrostatic GENEC models already published in the literature.
Results: We show that the mass of spherical SMSs forming in atomically cooled halos cannot exceed 500 000 M⊙, which stands in contrast to previous claims. On the other hand, masses in excess of this limit, possibly up to ∼106 M⊙, could be reached in alternative versions of direct collapse.
Conclusions: Our method can be used to test the consistency of GR hydrodynamical stellar evolution codes.
- Publication:
-
Astronomy and Astrophysics
- Pub Date:
- March 2021
- DOI:
- 10.1051/0004-6361/202039686
- arXiv:
- arXiv:2010.08229
- Bibcode:
- 2021A&A...647A..83H
- Keywords:
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- stars: massive;
- Astrophysics - High Energy Astrophysical Phenomena;
- Astrophysics - Solar and Stellar Astrophysics
- E-Print:
- A&