Evolution of supermassive stars as a pathway to black hole formation

By M. Begelman. 2009

152 citations recorded by the source corpus.

Supermassive stars, with masses ≳10 6 M ⊙ , are possible progenitors of supermassive black holes in galactic nuclei. Because of their short nuclear burning time-scales, such objects can be formed only when matter is able to accumulate at a rate exceeding ~ 1 M ⊙ yr -1 . Here we revisit the structure and evolution of rotationally stabilized supermassive stars, taking into account their continuous accumulation of mass and their thermal relaxation. We show that the outer layers of a supermassive star are not thermally relaxed during much of the star's main-sequence lifetime. As a result, they do not resemble n = 3 polytropes, as assumed in previous literature, but rather consist of convective (polytropic) cores surrounded by convectively stable envelopes that contain most of the mass. We compute the structures of these envelopes, in which the equation of state obeys P/ρ 4/3 ∝ M 2/3 (R), where M(R) is the mass enclosed within radius R. By matching the envelope solutions to convective cores, we calculate the core mass as a function of time. We estimate the initial black hole masses formed as a result of core-collapse, and their subsequent growth via accretion from the bloated envelopes ('quasi-stars') that result. The seed black holes formed in this way could have typical masses in the range ~10 4 -10 5 M ⊙ , considerably larger than the remnants thought to be left by the demise of Population III stars. Supermassive black holes therefore could have been seeded during an epoch of rapid infall considerably later than the era of Population III star formation.

Subfields: Astronomy and Astrophysics

View Paper: https://www.semanticscholar.org/paper/c5cde6c466245c3ea7e1a3446a3dce8d033ebd9b

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Citations in the corpus

Formation of supermassive black holes (2010, background): “If the mass accumulation is fast, however, the outer layers of SMSs are not thermally relaxed during much of the main sequence lifetime of the star (Begelman, 2009).”
Ubiquitous seeding of supermassive black holes by direct collapse (2012, background): “Another possibility is via the detection of SMSs in the planned surveys of the JWST which could also shed light on the plausibility of this scenario as a SMS is believed to be the precursor of a DCBH (e.g. Begelman 2010).”
Formation of Supermassive Black Hole Seeds (2016, background): “In the following subsections, we discuss physical processes involved in the formation of DCBHs via isothermal collapse, how and under what conditions they are formed and what are their typical masses.”
SUPER-CRITICAL GROWTH OF MASSIVE BLACK HOLES FROM STELLAR-MASS SEEDS (2014, background): “…gas at high redshift (e.g. Loeb & Rasio 1994; Bromm & Loeb 2003; Koushiappas et al. 2004; Lodato & Natarajan 2006; Spaans & Silk 2006; Regan & Haehnelt 2009; Mayer et al. 2010), likely via the intermediate stage of supermassive stars (Begelman 2010), and therefore “jump start” the whole process.”
What drives the growth of black holes (2011, background): “A related possibility is that direct collapse does not occur in an isolated halo, but is triggered by the mergers of multiple halos, providing highly unstable conditions and large gas inflow rates > 1 M yr−1 (e.g., Volonteri & Begelman, 2010; Begelman, 2010).”
FORMATION OF PRIMORDIAL SUPERMASSIVE STARS BY RAPID MASS ACCRETION (2013, background): “However, they do not consider the formation stage with rapid mass accretion, which could significantly change the stellar structure (e.g., Begelman 2010; Hosokawa et al. 2012a; Schleicher et al. 2013).”
Faint high-redshift AGN in the Chandra deep field south: the evolution of the AGN luminosity function and black hole demography (2011, background): “Two main scenarios have been proposed: the monolithic collapse of 104−105 M gas clouds to form BH (Lodato & Natarajan 2006, 2007; Begelman 2010; Volonteri & Begelman 2010) and the early generation of ∼100 M BH produced by the supernova explosions of the first Pop III stars (Madau & Rees 2001).”
The First Billion Years project: the impact of stellar radiation on the co-evolution of Populations II and III (2012, background): “…the primordial gas is expected to collapse to a supermassive star that grows via accretion to a mass > ∼ 104 M⊙ before collapsing to a black hole of similar mass (e.g. Shang et al. 2010; Johnson et al. 2012; see also e.g. Begelman 2010; Ball et al. 2011; Dotan & Shaviv 2012; Hosokawa et al. 2012).”