Actinide opacities for modeling the spectra and light curves of kilonovae

Abstract

We extend previous ab initio calculations of lanthanide opacities (Fontes et al., 2020, MNRAS, 493, 4143) to include a complete set of actinide opacities for use in the modeling of kilonova light curves and spectra. Detailed, fine-structure line features are generated using the configuration-interaction approach. These actinide opacities display similar trends to those observed for lanthanide opacities, such as the lighter actinides producing higher opacity than the heavier ones for relevant conditions in the dynamical ejecta. A line-binned treatment is employed to pre-compute opacity tables for 14 actinide elements $(89\le Z\le 102)$ over a grid of relevant temperatures and densities. These tabular opacities will be made publicly available for general usage in kilonova modeling. We demonstrate the usefulness of these opacities in kilonova simulations by exploring the sensitivity of light curves and spectra to different actinide abundance distributions that are predicted by different nuclear theories, as well as to different choices of ejecta mass and velocity. We find very little sensitivity to the two considered distributions, indicating that opacities for actinides with $Z\ge 99$ do not contribute strongly. On the other hand, a single actinide element, protactinium, is found to produce faint spectral features in the far infrared at late times (5-7 days post merger). More generally, we find that the choice of ejecta mass and velocity have the most significant effect on KN emission for this study.

18 pages, 14 figures

References in corpus (17)

• GW170817: Observation of Gravitational Waves from a Binary Neutron Star Inspiral
• Multi-messenger Observations of a Binary Neutron Star Merger
• Origin of the heavy elements in binary neutron-star mergers from a gravitational wave event
• The X-ray counterpart to the gravitational wave event GW 170817
• The Emergence of a Lanthanide-Rich Kilonova Following the Merger of Two Neutron Stars
• Identification of strontium in the merger of two neutron stars
• Kilonova Light Curves from the Disk Wind Outflows of Compact Object Mergers
• Properties of Kilonovae from Dynamical and Post-Merger Ejecta of Neutron Star Mergers
• Signatures of r-process elements in kilonova spectra
• Simulations of early kilonova emission from neutron star mergers
• Neutron-gamma competition for $\beta$-delayed neutron emission
• Extended calculations of energy levels and transition rates of Nd II-IV ions for application to neutron star mergers
• Kilonova Detectability with Wide-Field Instruments
• Estimation of M1 scissors mode strength for deformed nuclei in the medium to heavy mass region by statistical Hauser-Feshbach model calculations
• Radiation Transport for Explosive Outflows: Opacity Regrouping
• Nebular Emission from Lanthanide-rich Ejecta of Neutron Star Merger
• Interpolating Detailed Simulations of Kilonovae: Adaptive Learning and Parameter Inference Applications

Cited by in corpus (12)

• The critical role of nuclear heating rates, thermalization efficiencies and opacities for kilonova modelling and parameter inference
• Nucleosynthesis and observation of the heaviest elements
• NLTE Spectra of Kilonovae
• Opacities of Singly and Doubly Ionised Neodymium and Uranium for Kilonova Emission Modeling
• Superheavy Elements in Kilonovae
• Surrogate light curve models for kilonovae with comprehensive wind ejecta outflows and parameter estimation for AT2017gfo
• An Expanded Set of Los Alamos OPLIB Tables in MESA: Type-1 Rosseland-mean Opacities and Solar Models
• Actinide signatures in low electron fraction kilonova ejecta
• Kilonova ejecta opacity inferred from new large-scale HFR atomic calculations in all elements between Ca (Z = 20) and Lr (Z = 103)
• Impact of Ejecta Temperature and Mass on the Strength of Heavy Element Signatures in Kilonovae
• Impact of in situ nuclear networks and atomic opacities on neutron star merger ejecta dynamics, nucleosynthesis, and kilonovae
• Benford's law in atomic spectra and opacity databases