The Physics of Proto-Neutron Star Winds: Implications for r-Process Nucleosynthesis

By T. Thompson, Adam Burrows, B. Meyer. 2001

239 citations recorded by the source corpus.

We solve the general-relativistic steady-state eigenvalue problem of neutrino-driven proto-neutron star winds, which immediately follow core-collapse supernova explosions. We provide velocity, density, temperature, and composition profiles and explore the systematics and structures generic to such a wind for a variety of proto-neutron star characteristics. Furthermore, we derive the entropy, dynamical timescale, and neutron-to-seed ratio in the general relativistic framework essential in assessing this site as a candidate for r-process nucleosynthesis. Generally, we find that for a given mass outflow rate (), the dynamical timescale of the wind is significantly shorter than previously thought. We argue against the existence or viability of a high entropy (≳300 per kB per baryon), long dynamical timescale r-process epoch. In support of this conclusion, we model the proto-neutron star cooling phase, calculate nucleosynthetic yields in our steady-state profiles, and estimate the integrated mass loss. We find that transonic winds enter a high-entropy phase only with very low (≲1 × 10-9 M☉ s-1) and extremely long dynamical timescale (τρ ≳ 0.5 s). Our results support the possible existence of an early r-process epoch at modest entropy (~150) and very short dynamical timescale, consistent in our calculations with a very massive or very compact proto-neutron star that contracts rapidly after the preceding supernova. We explore possible modifications to our models, which might yield significant r-process nucleosynthesis generically. Finally, we speculate on the effect of fallback and shocks on both the wind physics and nucleosynthesis. We find that a termination or reverse shock in the wind, but exterior to the wind sonic point, may have important nucleosynthetic consequences. The potential for the r-process in proto-neutron star winds remains an open question.

Subfields: Astronomy and Astrophysics, Nuclear and High Energy Physics

View Paper: https://www.semanticscholar.org/paper/5eec47f0ba5f9626f8884d505fe86c706005b6a5

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Citations in the corpus

CHARGED-PARTICLE AND NEUTRON-CAPTURE PROCESSES IN THE HIGH-ENTROPY WIND OF CORE-COLLAPSE SUPERNOVAE (2010, background): “However, from the beginning problems were encountered to attain entropies sufficiently high in order to produce the heaviest r-process nuclei (see, e.g., Takahashi et al. 1994; Woosley et al. 1994; Thompson et al. 2001; Wanajo et al. 2001; Terasawa et al. 2002).”
Time-dependent models of accretion discs formed from compact object mergers (2008, background): “Purely neutrino-driven winds achieve asymptotic velocities which are typically below the escape speed of the central object (e.g., Thompson et al. 2001); thus, the asymptotic kinetic energy is most likely dominated by energy released during the formation of heavy elements.”
Short-duration gamma-ray bursts with extended emission from protomagnetar spin-down (2007, background): “…conclusion for moderately low latitudes, the centrifugal enhancement of mass loss along the rotation axis is negligible; hence, the total mass loss per solid angle near the rotation axis is approximately given by its non-rotating value of MΩ ∼ 10 −5M⊙ str −1 (Thompson et al. 2001; hereafter T01).”
Supernova Simulations with Boltzmann Neutrino Transport: A Comparison of Methods (2003, background): “…star surface causes a postexplosion outflow of baryonic matter, the so-called neutrino-driven wind, which is discussed as a potential site for the formation of r-process elements (Woosley et al. 1994; Takahashi et al. 1994; Sumiyoshi et al. 2000; Wanajo et al. 2001; Thompson et al. 2001).”
Multidimensional supernova simulations with approximative neutrino transport. I. Neutron star kicks and the anisotropy of neutrino-driven explosions in two spatial dimensions (2006, background): “This fraction declines because the wind power is proportional to a higher power of the luminosity (Lwind ∝ Lαν with α ≈ 3; Thompson et al. 2001) and although the mass in the gain layer at the onset of the explosion scales linearly with the boundary luminosity (Fig.”
Viscosity and Rotation in Core-Collapse Supernovae (2004, result): “…of entropy, mass-loss rate, and electron fraction all show that a quasi–steady state solution, quantitatively similar to that expected from the models of Thompson et al. (2001) and the analytic estimates of Qian &Woosley (1996), is obtained as the PNS begins the Kelvin-Helmholtz cooling epoch.”
Presupernova Evolution of Differentially Rotating Massive Stars Including Magnetic Fields (2004, background): “This powerful flux of neutrinos passing through the proto-neutron star atmosphere drives mass loss and the neutron star loses ∼ 0.01M⊙ (Duncan et al. 1986; Qian & Woosley 1996; Thompson et al. 2001).”
Galactic r-process enrichment by neutron star mergers in cosmological simulations of a Milky Way-mass galaxy (2014, methodology): “In particular, current models of nucleosynthesis in core-collapse supernovae fail to produce the requisite conditions, although the uncertainties remain large (e.g. Qian & Woosley 1996; Thompson et al. 2001; Hüdepohl et al. 2010).”
The Proto-Magnetar Model for Gamma-Ray Bursts (2010, methodology): “The normalization adopted in equation (A8) includes both this averaging and a general relativistic correction (Thompson et al. 2001).”
MAGNETOROTATIONALLY DRIVEN SUPERNOVAE AS THE ORIGIN OF EARLY GALAXY r-PROCESS ELEMENTS? (2012, background): “…supernovae (Hoffman et al. 1997; Meyer & Brown 1997; Farouqi et al. 2010) (a) did not result in having sufficiently high entropies (Thompson et al. 2001; Wanajo 2006; Arcones et al. 2007), and (b) in addition, the innermost ejecta turned out to be proton-rich instead of…”
THE LANDSCAPE OF THE NEUTRINO MECHANISM OF CORE-COLLAPSE SUPERNOVAE: NEUTRON STAR AND BLACK HOLE MASS FUNCTIONS, EXPLOSION ENERGIES, AND NICKEL YIELDS (2014, background): “Thompson et al. (2001) performed more detailed calculations of the neutrino-driven wind and found κ ≈ 3.2 to 3.4.”
Protoneutron star evolution and the neutrino-driven wind in general relativistic neutrino radiation hydrodynamics simulations (2009, methodology): “Hence, such models explore the neutrino driven wind by varying the neutrino luminosities and energies, where the simplified radiation-hydrodynamics equations are solved (see for example Thompson et al. (2001)).”
Neutron star mergers versus core-collapse supernovae as dominant r-process sites in the early Galaxy (2003, background): “…driven winds or jets from nascent neutronstars during the delayed explosion of high-mass stars with masses ≥ 20M⊙ (e.g. Woosley & Hoffman 1992; Takahashi et al. 1994; Woosley et al. 1994; Qian & Woosley 1996; Thompson et al. 2001; Nagataki 2001; Wanajo et al. 2001, 2002; Terasawa et al. 2002).”
Where, oh where has the r-process gone? (2007, background): “These parameters are determined in turn by the state of the neutron star that is defined by its mass MNS and radius RNS as well as its neutrino emission characteristics when the mass element is ejected [e.g., Qian & Woosley (1996); Thompson et al. (2001)].”