Three-dimensional spectral modelling of astrophysical transients : unravelling the nucleosynthetic content of supernovae and kilonovae

ended

Determining the origin of the elements is a fundamental quest in physics and astronomy. Most of the elements in the periodic table are believed to be produced by supernovae and kilonovae. However, this has for decades been little more than a prediction from theory. Now, with a dramatically changing observational situation and new modelling capabilities, it is within our reach to determine the nucleosynthesis production and structure in these transients. To really see what supernovae and kilonovae contain, we must study their spectra in the later so called nebular phase when the inner regions become visible. This project is aimed at establishing the first picture of the origin of elements by determining the yields from supernovae and kilonovae using such analysis. To do this, new spectral synthesis methods need to be developed considering the necessary microphysical (ejecta chemistry, r-process physics, time-dependent gas state) and macrophysical (3D radiation transport) processes to obtain sufficient accuracy. These tools will then be applied to the first 3D explosion simulations of these transients now becoming available. When applied to the growing library of data emerging from automated surveys and follow-up programs, as well to the recent first kilonova observations, this will provide a breakthrough in our understanding of these transients. This development will not only allow a determination of cosmic element production, but also allow tests of theories for stellar evolution, nucleosynthesis, and explosion processes. This will in turn have fundamental impact on several fields of astrophysics such as population synthesis, galactic chemical evolution modelling, and understanding of mass transfer in the progenitor systems. It has a strong connection to recent detections of stellar-mass black holes and merging neutron stars by gravitational waves.