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Understanding R-process & Kilonovae Aspects (URKA)
PI: Sergio Cristallo (CUP: C53D23001260006; FUNDED: 111.433 €)
Abstract
“How were the elements from Iron to Uranium made?" This is one of the eleven questions at the intersections of astrophysics
and nuclear physics, that are of high interest to the scientific community.
Half of the heavy elements in the Universe are synthesized via the rapid neutron capture process in stars (r-process),
proved to be at work during Neutron Star Mergers, by observing and interpreting the electromagnetic transient (the
so-called kilonova) following the gravitational event GW170817. An in-depth understanding of the r-process and kilonovae events is
therefore crucial to fully exploit the potentiality of multi-messenger astronomy in the next few years.
The **URKA** project will provide a comprehensive vision, spanning from experimental nuclear physics to atomic physics and
nucleosynthesis modeling.
Expected and current results
The huge literature of the last demonstrated that the amount of mass ejected during a BNS event
strongly influences the following nucleosynthesis. Thus, a proper evaluation of this quantity is a priority. Moreover, statistical studies with different
ejected masses for the various components of BNS mergers (dynamical, disk, wind) will be of dramatic importance as soon as the next class of
interferometers, such as the Einstein Telescope, will be at work. The original aim of the project was to explore a large
range of BNS systems and carefully trace for all of them the various components. To date, 12 models have been computed, with the M1
neutrino scheme and with the possibility to map, by means of trajectories, how physical conditions of the ejecta evolve. Before computing the relative
nucleosynthesis, a set of trajectories will be extracted (3000 over more than 100000 for each model) and masses will be assigned
(highlighting different components, angles and neutron richness). The corresponding r-process nucleosynthesis will be then calculated
with the WINNET code. We are currently running nucleosynthesis calculations on the first systems: results will be soon available on the MARTINI PLatform.
Another working package of the projects is related to heavy element atomic opacities, which represent a
fundamental input to properly compute KLs. In the last year we computed selenium atomic levels for different ionization stages using
the GRASP2018 code. Then, we were able to derive atomic opacities for that element as a function of wavelengths. With new results, we computed radiative
transfer calculations with the POSSIS code and lightcurves and spectra at various
epochs. Results are already available on the MARTINI Platform.
Future activities
In the next months results of BNS calculations and nucleosynthesis will be available on MARTINI. Atomic opacities for other heavy elements (e.g. Zr) will be soon available on MARTINI as well.