Neutrino Driven Explosions aided by Axion Cooling in Multidimensional Simulations of Core-Collapse Supernovae

In this study, we present the first multidimensional core-collapse supernovae (CCSNe) simulations including QCD axions in order to assess the impact on the CCSN explosion mechanism. We include axions in our simulations through the nucleon-nucleon bremsstrahlung emission channel and as a pure energy-sink term under the assumption that the axions free-stream after being emitted. We perform both spherically symmetric (1D) and axisymmetric (2D) simulations. In 1D, we utilize a parameterized heating scheme to achieve explosions, whereas in 2D we self-consistently realize explosions through the neutrino heating mechanism. Our 2D results for a $20 M_\odot$ progenitor show an impact of the axion emission on the shock behavior and the explosion time when considering values of the Peccei-Quinn energy scale $f_a \leq 2 \times 10^8$ GeV. The strong cooling due to the axion emission accelerates the contraction of the core and leads to more efficient neutrino heating and earlier explosions. For the axion emission formalism utilized, the values of $f_a$ that impact the explosion are close to, but in tension with current limits based on the neutrinos detected from SN1987A. However, given the non-linear behavior of the emission and the multidimensional nature of CCSNe,we suggest that a self-consistent, multidimensional approach to simulating CCSNe, including any late time accretion and cooling, is needed to fully explore the axion bounds from supernovae and the impact on the CCSN explosion mechanism.Comment: 19 pages, 13 figure

Neutrino interactions and axion emission impact on core-collapse supernova simulations

Core-Collapse Supernovae (CCSNe) are important phenomena in the scope of nucleosynthesis and, as the final stage of massive stars' life, they are key processes in the understanding of stellar evolution. They also are the birthplace of neutron stars and black holes, therefore they play a major role in the modelling and understanding of compact object mergers. While CCSNe have been observed for a long time, it is mainly through electromagnetic radiation. This channel gives us precious information about the explosion energy and nucleosynthesis, but fails to inform us about the collapse and initial explosion mechanism. While other observational channels are becoming available, through neutrino detection and gravitational waves, we are still waiting for a galactic CCSN to get an appropriate signal giving us insight on the explosion mechanism. We, therefore, have to rely on simulations for now. CCSN simulations have been performed for 60 years, improving decade after decade, and are now able to produce systematic self-consistent explosions. Several parameters impact the final outcome of our simulations, originating from different physics treatments, such as the gravity, neutrino transport and interactions, micro-physics through the equation of state, or magnetic fields. To understand the explosion mechanism behind a CCSN, we need to study the impact of each of these uncertain pieces of physics. In this thesis, I focused on the impact of the emission of heavy-lepton neutrinos and axions on the explosion, concentrated on the early proto-neutron star cooling. I explain details of the CCSN process, as well as some of the particle physics I focused on. I show how a change in heavy-lepton neutrino and axion emissions can accelerate the early proto-neutron star cooling and subsequently help the explosion

Neutrino interactions and axion emission impact on core-collapse supernova simulations

Core-Collapse Supernovae (CCSNe) are important phenomena in the scope of nucleosynthesis and, as the final stage of massive stars' life, they are key processes in the understanding of stellar evolution. They also are the birthplace of neutron stars and black holes, therefore they play a major role in the modelling and understanding of compact object mergers. While CCSNe have been observed for a long time, it is mainly through electromagnetic radiation. This channel gives us precious information about the explosion energy and nucleosynthesis, but fails to inform us about the collapse and initial explosion mechanism. While other observational channels are becoming available, through neutrino detection and gravitational waves, we are still waiting for a galactic CCSN to get an appropriate signal giving us insight on the explosion mechanism. We, therefore, have to rely on simulations for now. CCSN simulations have been performed for 60 years, improving decade after decade, and are now able to produce systematic self-consistent explosions. Several parameters impact the final outcome of our simulations, originating from different physics treatments, such as the gravity, neutrino transport and interactions, micro-physics through the equation of state, or magnetic fields. To understand the explosion mechanism behind a CCSN, we need to study the impact of each of these uncertain pieces of physics. In this thesis, I focused on the impact of the emission of heavy-lepton neutrinos and axions on the explosion, concentrated on the early proto-neutron star cooling. I explain details of the CCSN process, as well as some of the particle physics I focused on. I show how a change in heavy-lepton neutrino and axion emissions can accelerate the early proto-neutron star cooling and subsequently help the explosion