The First Stars: Mass Growth Under Protostellar Feedback

By A. Stacy, Thomas Greif, Volker Bromm. 2011

208 citations recorded by the source corpus.

We perform three-dimensional cosmological simulations to examine the growth of metal-free, Population III (Pop III) stars under radiative feedback. We begin our simulation at z = 100 and trace the evolution of gas and dark matter until the formation of the first minihalo. We then follow the collapse of the gas within the minihalo up to densities of n = 10 12 cm −3 , at which point we replace the high-density particles with a sink particle to represent the growing protostar. We model the effect of Lyman-Werner (LW) radiation emitted by the protostar, and employ a ray-tracing scheme to follow the growth of the surrounding H ii region over the next 5000 yr. We find that a disk assembles around the first protostar, and that radiative feedback will not prevent further fragmentation of the disk to form multiple Pop III stars. Ionization of neutral hydrogen and photodissociation of H2 by LW radiation leads to heating of the dense gas to several thousand Kelvin, and this warm region expands outward at the gas sound speed. Once the extent of this warm region becomes equivalent to the size of the disk, the disk mass declines while the accretion rate onto the protostars is reduced by an order of magnitude. This occurs when the largest sink has grown to � 20 M⊙ while the second sink has grown to � 7 M⊙, and we estimate the main sink will approach an asymptotic value of 30 M⊙ by the time it reaches the main sequence. Our simulation thus indicates that the most likely outcome is a massive Pop III binary. However, we simulate only one minihalo, and the statistical variation between minihaloes may be substantial. If Pop III stars were typically unable to grow to more than a few tens of solar masses, this would have important consequences for the occurence of pair-instability supernovae in the early Universe as well as the Pop III chemical signature in the oldest stars observable today.

Subfields: Astronomy and Astrophysics, Instrumentation, Statistical and Nonlinear Physics

View Paper: https://www.semanticscholar.org/paper/669acc9edf9e6912b047005a15f53aab2a9add92

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Citations in the corpus

FORMATION OF PRIMORDIAL SUPERMASSIVE STARS BY RAPID MASS ACCRETION (2013, background): “In disk geometries, however, a bipolar Hii region should emerge and strong UV feedback could limit mass accretion much earlier, as expected in the standard cases of primordial star formation (e.g., McKee & Tan 2008; Hosokawa et al. 2011b; Stacy et al. 2012; Susa 2013).”
THE MASS SPECTRUM OF THE FIRST STARS (2014, background): “We also adopt artificially enhanced normalizations of the power spectrum, σ8 = 1.5, and 1.2 to accelerate the structure formation in the same manner as previous studies (e.g., Stacy et al. 2012).”
Building up the Population III initial mass function from cosmological initial conditions (2016, methodology): “An approximation for pressure from Lyα can be found in, e.g., Bithell (1990); Oh & Haiman (2002), and was also presented in Stacy et al. (2012): Pα = ṄLyα 4πr2 ( hνα c ) Nscat , (5) where ṄLyα is the emission rate of Lyα photons, hνα ∼ 10.2 eV is the energy of a Lyα photon, and Nscat is the…”
Formation and evolution of primordial protostellar systems (2012, background): “In addition, we have not accurately solved for the radiation emitted by the protostars, which could significantly affect the chemical and thermal evolution of the gas (Hosokawa et al. 2011; Smith et al. 2011a,b; Stacy et al. 2012).”
ONE HUNDRED FIRST STARS: PROTOSTELLAR EVOLUTION AND THE FINAL MASSES (2013, background): “The first such simulations of Hosokawa et al. (2011) show that the UV radiative feedback is strong enough to halt gas accretion when the stellar mass is around a few tens of solar masses (see also Stacy et al. 2012; Susa 2013).”
Observational evidence for intermediate-mass black holes (2017, background): “However, the existence of numerous isolated stars more massive than 260 M has been put into doubt by simulations showing that Pop III stars may instead form in binaries or multiple systems of 10–100 M (e.g., Turk et al. 2009; Clark et al. 2011; Stacy et al. 2012; see review by Greif 2015).”
Possible indirect confirmation of the existence of Pop III massive stars by gravitational wave (2014, methodology): “Recent numerical simulations (e.g. Hosokawa et al. 2011, 2012; Stacy et al. 2012) suggest that the Pop III protostar can grow to approximately several tens of M until the radiation feedback halts the gas accretion on to the central protostar.”
Formation of Supermassive Black Hole Seeds (2016, methodology): “However, simulations taking into account the UV feedback from the protostar show that it shuts accretion onto the protostar by photoevaporating the protostellar disk and the central star cannot grow beyond 40 M⊙ (Hosokawa et al. 2011; Stacy et al. 2012).”
The First Billion Years project: the escape fraction of ionizing photons in the epoch of reionization (2015, background): “Recent cosmological simulations of Pop III star formation in which radiative feedback was taken into account show that these stars form with masses within this range (Hosokawa et al. 2011; Stacy et al. 2012).”
The First Billion Years project: the impact of stellar radiation on the co-evolution of Populations II and III (2012, background): “Finally, we note that recent cosmological simulations which have modelled the radiative feedback from Pop III stars suggest that they may typically form with masses within the range we have chosen (see e.g. Hosokawa et al. 2011; Stacy et al. 2012).”
Primordial star formation under the influence of far ultraviolet radiation: 1540 cosmological haloes and the stellar mass distribution (2015, methodology): “More recently, the feedback process has been studied with multidimensional radiation hydrodynamic (RHD) numerical simulations (Hosokawa et al. 2011; Stacy et al. 2012; Susa 2013), demonstrating that UV radiative feedback does indeed shut off the mass accretion and the resulting stellar masses can…”
FORMATION OF MASSIVE PRIMORDIAL STARS: INTERMITTENT UV FEEDBACK WITH EPISODIC MASS ACCRETION (2015, background): “Whereas the first 3D simulations mostly focused on the early evolution for 10− 103 years after the birth of the protostar, Stacy et al. (2012) follow for longer periods (' 5 × 103 years), namely until UV feedback begins to operate.”