A new study published in Physics Letters investigated the possibility of incorporating flavor-related quantum mechanical effects into the neutrino transport within a neutron star merger remnant using a semi-classical angular moment-based method.
Three-dimensional contours of quantum coherence in a neutrino moment simulation. The simulation starts with random initial conditions and develops structure in less than a nanosecond. Image Credit: E. Grohs
“Flavor” is a quantum mechanical feature of neutrinos. This particle's flavor can change as it travels across space. Monitoring neutrinos' motion and flavor shift in astrophysical systems, such as neutron star mergers and core-collapse supernovae, is a significant problem.
Due to their complex structure and vast number, it is practically hard to follow all or even a fraction of the neutrinos in these systems. In this study, researchers looked at a potential solution to this problem. The strategy extends traditional neutrino movement calculations to incorporate quantum mechanical flavor modification. This method simplifies the computation of neutrino behavior in intricate systems.
The Impact
A supernova or neutron star merger emits various messengers, including photons, gravitational waves, neutrinos, and heavy elements. These messengers supply scientists with fresh information about the mechanics of these celestial objects. Nevertheless, to utilize these signals, scientists must comprehend neutrino physics.
Neutrinos carry a significant fraction of the energy in these systems. To forecast the heavy components resulting from star explosions and mergers, scientists must comprehend the interactions involving neutrinos. Angular moments are a compact collection of equations of motion that capture the overall amount and flow of neutrinos.
Scientists can then employ these equations to determine how neutrinos' flavors change. The angular moment method's fewer equations provide a way to solve neutrino flavor-transformation issues in compact astrophysical objects, such as neutron star mergers.
Summary
The technique was tested on a neutrino flavor transformation known as "fast flavor," for which the transformation requires angular information about the neutrinos. The technique effectively caught the transformation's growth, and more research into this approach is necessary.
The National Energy Research Scientific Computing Center, a Department of Energy user facility, provided computational resources for this study. The Payne machine at North Carolina State University, which receives funding from the Research Corporation for Science Advancement, was also utilized in this study.
Funding
The majority of the funding for this study came from the Department of Energy’s (DOE) Office of Science, Nuclear Physics program. Additional funding came from the National Science Foundation, the Heising-Simons Foundation, the National Aeronautics and Space Administration, the DOE Office of Science, and the Office of Advanced Scientific Computing Research.
Journal Reference:
Grohs, E., et al. (2023) Neutrino fast flavor instability in three dimensions for a neutron star merger. Physics Letters. doi:10.1016/j.physletb.2023.138210.
Grohs, E., et al. (2024) Two-moment Neutrino Flavor Transformation with Applications to the Fast Flavor Instability in Neutron Star Mergers. Astrophysical Journal. doi:10.3847/1538-4357/ad13f2.