On the Dynamics of Proto-Neutron Star Winds and r-Process Nucleosynthesis

Abstract

We study here the formation of heavy r-process nuclei in the high-entropy environment of rapidly expanding neutrino-driven winds from compact objects. In particular, we explore the sensitivity of the element creation in the A>130 region to the low-temperature behavior of the outflows. For this purpose we employ a simplified model of the dynamics and thermodynamical evolution for radiation dominated, adiabatic outflows. It consists of a first stage of fast, exponential cooling, followed by a second phase of slower evolution, either assuming constant density and temperature or a power-law decay of these quantities. These cases are supposed to capture the most relevant effects of a strong deceleration or decreasing acceleration of the transsonic outflows, respectively, e.g. in a wind termination shock caused by the collision with the slower, preceding supernova ejecta. We find that not only the transition temperature between the two expansion phases can make a big difference in the formation of the platinum peak, but also the detailed cooling law during the later phase. Unless the transition temperature and corresponding (free neutron) density become too small (T < 2*10^8 K), a lower temperature or faster temperature decline during this phase allow for a stronger appearance of the third abundance peak. Since the nuclear photodisintegration rates between ~2*10^8 K and ~10^9 K are more sensitive to the temperature than the n-capture rates are to the free neutron density, a faster cooling in this temperature regime shifts the r-process path closer to the n-drip line. With low (gamma,n)- but high beta-decay rates, the r-processing then does not proceed through a (gamma,n)-(n,gamma) equilibrium but through a quasi-equilibrium of (n,gamma)-reactions and beta-decays, as recently also pointed out by Wanajo.

arXiv comment18 pages, 14 figures with 25 eps plots; referee comments included; accepted by Astronomy & Astrophysics

References in corpus (26)

• Nuclear Ground-State Masses and Deformations
• Astrophysical Reaction Rates From Statistical Model Calculations
• The r-process of stellar nucleosynthesis: Astrophysics and nuclear physics achievements and mysteries
• Nucleosynthesis in neutrino-driven winds: I. The physical conditions
• On the Nature of Core Collapse Supernova Explosions
• The Physics of Protoneutron Star Winds: Implications for r-Process Nucleosynthesis
• Nucleosynthesis in neutrino-driven winds: II. Implications for heavy element synthesis
• Two-Dimensional Hydrodynamic Core-Collapse Supernova Simulations with Spectral Neutrino Transport II. Models for Different Progenitor Stars
• Nucleosynthesis-relevant conditions in neutrino-driven supernova outflows. I. Spherically symmetric hydrodynamic simulations
• General relativistic effects on neutrino-driven wind from young, hot neutron star and the r-process nucleosynthesis
• The r-Process in Neutrino-Driven Winds from Nascent, "Compact" Neutron Stars of Core-Collapse Supernovae
• New Nuclear Reaction Flow during r-Process Nucleosynthesis in Supernovae: Critical Role of Light Neutron-Rich Nuclei
• Neutrino signatures of supernova shock and reverse shock propagation
• The r-process in the neutrino winds of core-collapse supernovae and U-Th cosmochronology
• Calculations of fission rates for r-process nucleosynthesis
• r-Process Calculations and Galactic Chemical Evolution
• The First Second of a Type-II Supernova: Convection, Accretion, and Shock Propagation
• General relativistic effects in the neutrino-driven wind and r-process nucleosynthesis
• The r-process nucleosynthesis: a continued challenge for nuclear physics and astrophysics
• Cold r-Process in Neutrino-Driven Winds
• Hydrodynamical study of neutrino-driven wind as an r-process site
• Stellar Abundances in the Early Galaxy and Two r-Process Components
• Fission Cycling in a Supernova r-process
• R-Process Nucleosynthesis In Neutrino-Driven Winds From A Typical Neutron Star With M = 1.4 Msun
• The r-Process in Supernovae: Impact of New Microscopic Mass Formulas
• Applicability Of The Hauser-Feshbach Approach For The Determination of Astrophysical Reaction Rates

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• Neutrino-driven wind simulations and nucleosynthesis of heavy elements
• Dynamical r-process studies within the neutrino-driven wind scenario and its sensitivity to the nuclear physics input
• Uncertainties in the nu p-process: supernova dynamics versus nuclear physics
• The influence of collective neutrino oscillations on a supernova r-process
• Modeling Kilonova Light Curves: Dependence on Nuclear Inputs
• Have Superheavy Elements been Produced in Nature?
• The r-process in the neutrino-driven wind from a black-hole torus
• Formation Of The Rare Earth Peak: Gaining Insight Into Late-Time r-Process Dynamics
• Nuclear-Astrophysics Lessons from INTEGRAL
• The Influence Of Neutron Capture Rates On The Rare Earth Region Of The r-Process Abundance Pattern
• Implications for Post-Processing Nucleosynthesis of Core-Collapse Supernova Models with Lagrangian Particles
• Neutrino Spectra from Accretion Disks: Neutrino General Relativistic Effects and the Consequences for Nucleosynthesis
• Introducing the Fission-Fusion Reaction Process: Using a Laser-Accelerated Th Beam to produce Neutron-Rich Nuclei towards the N=126 Waiting Point of the r Process
• Parameterizing the Supernova Engine and its Effects on Remnants and Basic Yields
• Beta decay of deformed r-process nuclei near A = 80 and A= 160, including odd-A and odd-odd nuclei, with the Skyrme finite-amplitude method
• Nucleosynthesis-relevant conditions in neutrino-driven supernova outflows. II. The reverse shock in two-dimensional simulations
• Impact of supernova dynamics on the νp-process
• Reverse engineering nuclear properties from rare earth abundances in the $r$ process
• Neutron capture on 130Sn during r-process freeze-out
• The barium isotopic fractions in five metal-poor stars
• The Influence of Beta Decay Rates on r-Process Observables
• Massive Stars and their Supernovae
• Nucleosynthesis in core-collapse supernova explosions triggered by a quark-hadron phase transition
• Exploring laser-driven neutron sources for neutron capture cascades and the production of neutron-rich isotopes
• Performance Improvements for Nuclear Reaction Network Integration
• Magnetars and Gamma Ray Bursts
• An Analytic Description of Electron Thermalization in Kilonovae Ejecta
• Dynamic model of a non-equilibrium chemical composition formation in the shell of single neutron stars
• Nucleosynthesis in neutrino-driven winds: influence of the nuclear physics input