Welcome

• Konrad Schmidt (HZDR, Germany)

Room: virtual Introduction of the interactive part of SNAQs

Rußbach school on nuclear astrophysics

• Olivier Sorlin (GANIL, France)

Room: virtual Introduction of the annual winter school on nuclear astrophysics

Multi-messenger astrophysics with merging neutron stars

• Stephan Rosswog (Stockholm University, Sweden)

Room: virtual First lecture on how neutron star mergers and impact r elements in the universe

Moderated questions

• Andreas Korn (Uppsala University, Sweden)

Room: virtual

Heavy element nucleosynthesis in neutron star mergers

• Gabriel Martínez-Pinedo (GSI, Germany)

Room: virtual Second lecture on how neutron star mergers and impact r elements in the universe

Moderated questions

• Olivier Sorlin (GANIL, France)

Room: virtual

Breakout Session Room: virtual Small groups of up to 5 participants are assigned to breakout rooms to (1) very briefly introduce yourself, (2) talk about the lectures, (3) clarify lecture items, and (4) phrase questions for the round table discussion. Afterwards, questions can be written in the chat of the main Zoom room. Please tag questions related to lecture 1 with L1 and questions related to lecture 2 with L2. Moderators can only choose a limited number of questions to be discussed at the round table discussion. This session also povides the opportunity to establish contacts that can be continued using the private chat. Networking is an important tool not only in science.

Impact of neutrino interaction on neutron star merger nucleosynthesis

• Ina Kullmann (Université Libre de Bruxelles, Belgium)

Room: virtual Hydrodynamical simulations of merging binary neutron stars (NS) follow the evolution and expansion of material at extreme densities, sometimes shock-heated to high temperatures, and determine the amount of ejected material and its history. To calculate the nucleosynthesis yields, the hydrodynamical models are complemented by full nuclear reaction networks involving ~5000 nuclear species, where most of the involved reaction rates rely on theoretical predictions. This talk will contribute to the question of whether a more accurate description of neutrino interactions can significantly affect the r-process in neutron star mergers and the decay heat produced by the recently synthesized radioactive r elements. We have studied the material ejected from four NS-NS merger systems based on the hydrodynamical simulations. The models simulate neutrino transport in a realistic way by including neutrino equilibration with matter in optically thick regions and re-absorption in optically thin regions. We find that the neutron richness is significantly affected by the neutrinos emitted by the post-merger remnant, in particular when compared to a case neglecting all neutrino interactions. Our nucleosynthesis results show that a solar-like distribution of r-process elements with mass numbers larger than 90, including actinides, are produced.

Moderated questions

• Gianluca Pizzone (Laboratori Nazionali del Sud, Italy)

Room: virtual

Constraining the rapid neutron-capture process with meteoritic I-129 and Cm-247

• Andrés Yagüe López (Konkoly Observatory, Hungary)

Room: virtual Among all radioactive isotopes produced in the Galaxy, a small number of them have relatively short mean lives between 0.1 and 100 million years. Early Solar System abundances of these radioisotopes can be determined through meteoritic analysis and, due to their short half-lives, give us insight into the sites and processes that produced them. In this talk, we discuss the ratio of two of these short-lived radioisotopes, the rapid neutron capture isotopes I-129 and Cm-247. We also show how, due to their remarkably similar half-lives, they give us a unique opportunity to constrain the physical conditions of the last r-process event that contributed to the enrichment of the pre-solar nebula. Following our nucleosynthesis calculations based on compact binary merger and magneto-rotational supernova simulations, we find that moderately neutron-rich conditions often found in merger disk ejecta simulations are most consistent with the meteoritic value.

Moderated questions

• Gianluca Pizzone (Laboratori Nazionali del Sud, Italy)

Room: virtual

Identification of strontium in the merger of two neutron stars

• Camilla Juul Hansen (MPIA, Germany)

Room: virtual Half of all of the elements in the Universe that are heavier than iron were created by rapid neutron capture. Existing models and circumstantial evidence point to neutron-star mergers as a probable r-process site. The optical and infrared transient that emerges in the days after a merger is a likely place to detect the spectral signatures of newly created neutron-capture elements. Detailed spectra were recorded for the kilonova AT2017gfo which was found following the discovery of the neutron-star merger GW170817 by gravitational-wave detectors. The talk will report the identification of the neutron-capture element strontium. The detection of a neutron-capture element associated with the collision of two extreme-density stars establishes the origin of r-process elements in neutron-star mergers, and shows that neutron stars are made of neutron-rich matter.

Moderated questions

• Gianluca Pizzone (Laboratori Nazionali del Sud, Italy)

Room: virtual

Round table discussion Room: virtual Questions that were compiled in the chat after the breakout session will be discussed by the lecturers.