Superheavy Elements in Kilonovae

Abstract

As LIGO-Virgo-KAGRA enters its fourth observing run, a new opportunity to search for electromagnetic counterparts of compact object mergers will also begin. The light curves and spectra from the first "kilonova" associated with a binary neutron star binary (NSM) suggests that these sites are hosts of the rapid neutron capture ("$r$") process. However, it is unknown just how robust elemental production can be in mergers. Identifying signposts of the production of particular nuclei is critical for fully understanding merger-driven heavy-element synthesis. In this study, we investigate the properties of very neutron rich nuclei for which superheavy elements ($Z\ge 104$) can be produced in NSMs and whether they can similarly imprint a unique signature on kilonova light-curve evolution. A superheavy-element signature in kilonovae represents a route to establishing a lower limit on heavy-element production in NSMs as well as possibly being the first evidence of superheavy element synthesis in nature. Favorable NSMs conditions yield a mass fraction of superheavy elements is $X_{Z\ge 104}\approx 3\times 10^{-2}$ at 7.5 hours post-merger. With this mass fraction of superheavy elements, we find that the component of kilonova light curves possibly containing superheavy elements may appear similar to those arising from lanthanide-poor ejecta. Therefore, photometric characterizations of superheavy-element rich kilonova may possibly misidentify them as lanthanide-poor events.

8 pages, 5 figures, 4 data tables

References in corpus (14)

• 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 Electromagnetic Counterpart of the Binary Neutron Star Merger LIGO/VIRGO GW170817. II. UV, Optical, and Near-IR Light Curves and Comparison to Kilonova Models
• A kilonova as the electromagnetic counterpart to a gravitational-wave source
• The Emergence of a Lanthanide-Rich Kilonova Following the Merger of Two Neutron Stars
• The Combined Ultraviolet, Optical, and Near-Infrared Light Curves of the Kilonova Associated with the Binary Neutron Star Merger GW170817: Unified Data Set, Analytic Models, and Physical Implications
• Identification of strontium in the merger of two neutron stars
• Kilonovae
• Time Dependent Monte Carlo Radiative Transfer Calculations For 3-Dimensional Supernova Spectra, Lightcurves, and Polarization
• Kilonova from post-merger ejecta as an optical and near-infrared counterpart of GW170817
• Monte Carlo Radiation Hydrodynamics with Implicit Methods
• Nucleosynthesis and observation of the heaviest elements
• Actinide opacities for modeling the spectra and light curves of kilonovae

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