In the last years, the search for the oldest stars has started to investigate the central region of our Galaxy and its outskirts with ultra-faint galaxies.
Both Galactic bulge and ultra-faint galaxies host extremely old stars, with ages compatible with the ages of the oldest halo stars. The data coming from these recent observations present new signatures in neutron capture elements. Our...
Over the past years the energy density functionals have been extensively used in nuclear physics and astrophysics research; there are more than 240 nonrelativistic Skyrme parametrizations and 260 relativistic-mean-field (RMF) models introduced so far. However, all of them are optimized mainly by the nuclear ground state data, often supplemented with pseudo-observables in order to set the...
Among the most difficult ingredients in models of neutron star mergers and core-collapse supernovae is the treatment of neutrinos. In this talk I will briefly summarize our understanding of the most important neutrino effects in the context of r-process nucleosynthesis and I will discuss a few recently proposed schemes and their pros and cons.
One of the open question of the r-process is whether neutron star mergers are the only site or whether there is an additional (rare) r-process site, possibly related to supernovae. In this talk, I will discuss neutron star and black hole distributions from core-collapse supernovae and how they may fit in with the notion of an additional rare r-process site.
Canonical core-collapse supernova explosions driven by the neutrino-heating mechanism are presently ruled out as nucleosynthesis site for the production of heavy r-process elements with A ~ 195 (third r-process peak). Detailed numerical studies, with accurate neutrino transport and a sophisticated treatment of weak processes included, have shown that the ejected material yields neither...
Nuclear fission is known to be of fundamental importance in many applications, for example for energy production applications, such as nuclear power reactors or nuclear waste recycling. In astrophysics, nuclear fission plays a significant role during the rapid neutron-capture process (r-process) of stellar nucleosynthesis by recycling the matter during the neutron irradiation occurring in a...
The observation of the electromagnetic counterpart of GW170817 gravitational wave hinted the production of r-process elements in the aftermath of neutron star mergers. The color of the electromagnetic counterpart suggests there are at least two different contributions of electron fraction ($Y_e$) distributions, one moderately high, reproducing the light r-process elements, and one $<0.25$...
Gravitational waves detection in neutron mergers and the parallel observations in the visual and IR spectrum have triggered a new era in astronomy, the so-called multi-messenger era, where information of astrophysical significance is carried by different messengers. The possibility to identify a source and follow its time evolution has opened a new window on exotic phenomena, allowing us to...
In this talk I will discuss experimental constraints to neutron-capture reactions far from stability. These reactions are a critical part of the r process, and to date are almost completely unconstrained experimentally. Measuring direct neutron-capture reactions on short-lived nuclei is extremely challenging, and therefore one has to rely on indirect constraints. I will discuss the...
The recent observation of neutron stars merger by the LIGO collaboration and the measurements of the event’s electromagnetic spectrum as a function of time for different wavelengths, have altered profoundly our understanding of the r-process site, as well as considerably energized nuclear astrophysics research efforts. R-process abundances are a key element in r-process...
In this presentation, I will expose some of the last developments in microscopic nuclear structure calculations for exotic nuclei far from stabilitity in the vicinity of $^{78}$Ni, in a key region needed for understanding nucleosynthesis paths of gold and some of the most heavy elements.
In a first part, I will expose recent study on the development of collectivity in neutron-rich nuclei...
The observation of the tidal deformability extracted from GW170817 have been analyzed by many teams, leading to boundaries of the NS radius. In our analysis, we contrast continuous EoS with EoS with strong first order phase transitions showing that these two cases induce different constrain on global NS properties. We also explore the impact of low density neutron matter predictions from...
The recent observation of neutron star mergers indicate the presence of the r-process in those events, but the precise elemental composition cannot be deduced from the multimessenger observations. Detailed information about the heavy, neutron-rich nuclei involved are needed in order to pin down the origin of heavy elements in the universe. The next-generation radioactive ion beam facility...
Quantifying the mass, or nuclear binding energy, of atomic nuclei is fundamental for understanding the origin of elements in the universe. The astrophysical processes responsible for the nucleosynthesis in stars often take place far from the valley of stability, where experimental masses are not known. Taking advantage of the information contained in mass model residuals, where the...
Sensitivity studies have shown the predominant role of 67Fe and 69Co on the weak r-process abundance pattern [1]. The individual photodissociation rates in the r-process path depend exponentially on the reaction Q-values. The Q-value for 67Fe(n,γ)68Fe and 68Co(n,γ)69Co reactions are based directly on the masses of 67Fe and 69Co. The double Penning trap JYFLTRAP [2] at the University of...
From low metallicity stars and the presence of radioactive isotopes in deep-sea sediments we know that the main r-process, producing the heaviest elements, is a rare event. The question remains whether neutron star mergers, via GW170817 the only proven r-process site, are the only contributors or also (a rare class of) supernovae, hypernovae/collapsars, as well as neutron star - black hole...
The very first detection of gravitational waves from a neutron-star merger and accompanying electromagnetic emission has provided a wealth of information on astrophysics and nuclear physics. In particular, these observations have established that neutron star mergers play an important role for the Galactic enrichment by r-process elements. We will provide a general overview on neutron star...
Half of the heavy elements are produced in r-process nucleosynthesis, which is exclusively responsible for actinide production. The abundance of long-lived actinides in today’s interstellar medium (ISM) results from the interplay between production and decay. Their presence would establish that their production was recent.
The solar system moves through the ISM and collects ISM dust...
Theoretical r-process models still suffer for severe uncertainties, regarding in particular the physical conditions characterizing the hosting site and the adopted nuclear inputs.
For this reason, the contribution of the r-process to the solar distribution is commonly derived by subtracting the contribution coming from the slow neutron capture process (s-process), as r=1-s.
This curve...
The properties of thousands of nuclear species far from stability set abundance patterns and other observables from r-process events. We will describe recent efforts to forge explicit links between the details of the r-process isotopic abundance pattern and specific nuclear properties, here focusing on masses and spallation cross sections. We will discuss future prospects given the anticipated...
Abstract: One of the primary mechanisms for guiding experimental research in nuclear astrophysics is the sensitivity study. In a broad sense, these studies involve a stellar model in which various quantities related to nuclear reactions are varied to examine the effects. These variables can include a single, or multiple, reaction rates, Q-values, nuclear masses, and others. Subsequently,...
A series of experiments have been planned to study the neutron rich A=98 chain of decay products, starting from the decay of $^{98}$Kr. Following systematic mass and charge radii studies of Rb, Sr and Y, the A=98 isotopes have displayed unique properties. These properties will be discussed and related to the motivation for the planned experiments to showcase a thorough study of the Kr,Rb, Sr...
Fission barriers of exotic nuclei and the role of fission in the r-process are intimately connected with the density dependence of the symmetry energy at the sub-saturation densities attained in the neck region at the maximum of the fission barrier. In our talk we will discuss the future experiment to measure the fission cross sections using radioactive beams with the Active Target Time...