EPJ D Highlight - Looking deeper into violent neutron star collisions to find the origins of heavy elements

An illustration of a kilonova the collision of neutron stars generating conditions extreme enough to forge the Universe’s heavy elements. Credit: Robin Dienel/The Carnegie Institution for ScienceContact

The gold that makes up your most precious jewellery may have been forged in a violent cosmic collision millions or billions of light years away between two neutron stars. New research seeks to better understand this process.

There is only a single confirmed site in the Universe capable of generating conditions extreme enough to initiate the production process for many of the heaviest elements in the Universe, including gold, platinum, uranium – neutron star mergers. These mergers are the only event observed to-date that can produce the incredible densities and temperatures needed to power the rapid neutron capture process.

In a new paper in EPJ D, Andrey Bondarev, a postdoc researcher at Helmholtz Institute Jena, James Gillanders a postdoc researcher in Rome, and their colleagues examine the spectra from the kilonova AT2017gfo to investigate the presence of forged tin, by looking for spectral features caused by its forbidden transitions.

“We have demonstrated that accurate atomic data, especially for forbidden magnetic dipole and electric quadrupole transitions, which are unknown for many elements, are important for kilonova analysis,” Bondarev says. “By calculating a large number of energy levels and rates of multipole transitions between them in singly ionized tin, using the method that combines linearised coupled-cluster and configuration interaction approaches, we generated an atomic data set that can be used for future astrophysical analysis.”

The team’s research shows that a magnetic dipole transition between the levels of the ground-state doublet of singly ionized tin leads to a prominent and observable feature in kilonova emission spectra.

“Although this does not match any prominent features in the AT2017gfo spectra, it can nevertheless be used as a probe for future kilonova events,” Gillanders explains. “The more elements that can be positively identified, the closer we get to understanding these incredible cosmic explosions.”

The team point out that kilonova events are only a recently observed phenomenon, with the first spectroscopic observations only obtained in 2017. Better atomic data such as that provided in this study will be essential in better understanding the explosive collisions associated with neutron star mergers.

“We hope our work can contribute in some way to the advancement of our understanding of the process that produces the heaviest elements in the Universe,” Gillanders concludes. “We are eager for the discovery of new kilonovae and associated new sets of observations, which will allow us to develop our understanding of these events.”

This was our first experience of publishing with EPJ Web of Conferences. We contacted the publisher in the middle of September, just one month prior to the Conference, but everything went through smoothly. We have had published MNPS Proceedings with different publishers in the past, and would like to tell that the EPJ Web of Conferences team was probably the best, very quick, helpful and interactive. Typically, we were getting responses from EPJ Web of Conferences team within less than an hour and have had help at every production stage.
We are very thankful to Solange Guenot, Web of Conferences Publishing Editor, and Isabelle Houlbert, Web of Conferences Production Editor, for their support. These ladies are top-level professionals, who made a great contribution to the success of this issue. We are fully satisfied with the publication of the Conference Proceedings and are looking forward to further cooperation. The publication was very fast, easy and of high quality. My colleagues and I strongly recommend EPJ Web of Conferences to anyone, who is interested in quick high-quality publication of conference proceedings.

On behalf of the Organizing and Program Committees and Editorial Team of MNPS-2019, Dr. Alexey B. Nadykto, Moscow State Technological University “STANKIN”, Moscow, Russia. EPJ Web of Conferences vol. 224 (2019)

ISSN: 2100-014X (Electronic Edition)

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