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Presolar Grains as Probes of Supernova Nucleosynthesis.
Space Sci Rev
November 2024
Institute for Geochemistry and Petrology, ETH Zürich, 8092 Zurich, Switzerland.
We provide an overview of the isotopic signatures of presolar supernova grains, specifically focusing on Ti-containing grains with robustly inferred supernova origins and their implications for nucleosynthesis and mixing mechanisms in supernovae. Recent technique advancements have enabled the differentiation between radiogenic (from Ti decay) and nonradiogenic Ca excesses in presolar grains, made possible by enhanced spatial resolution of Ca-Ti isotope analyses with the Cameca NanoSIMS (Nano-scale Secondary Ion Mass Spectrometer) instrument. Within the context of presolar supernova grain data, we discuss () the production of Ti in supernovae and the impact of interstellar medium heterogeneities on the galactic chemical evolution of Ca/Ca, () the nucleosynthesis processes of neutron bursts and explosive H-burning in Type II supernovae, and () challenges in identifying the progenitor supernovae for Cr-rich presolar nanospinel grains.
View Article and Find Full Text PDFHigh-temperature Tl decay clarifies Pb dating in early Solar System.
Nature
November 2024
GSI Helmholtzzentrum für Schwerionenforschung GmbH, Darmstadt, Germany.
Article Synopsis
- Radioactive nuclei that live for millions of years help us understand the Sun's formation and the nucleosynthesis happening when it was born, with lead (Pb) being a key example.
- Recent measurements of the weak decay of ionized thallium (Tl) provided a more accurate half-life, which was found to be 4.7 times longer than previously thought, thus reducing uncertainty in our calculations.
- Using these improved decay rates, researchers calculated lead yields in asymptotic giant branch (AGB) stars, confirmed isolation times for solar material, and validated the theory that the Sun formed in a long-lived molecular cloud.
Enhanced production of Fe in massive stars.
Nat Commun
November 2024
Lawrence Livermore National Laboratory, Livermore, CA, USA.
Massive stars are a major source of chemical elements in the cosmos, ejecting freshly produced nuclei through winds and core-collapse supernova explosions into the interstellar medium. Among the material ejected, long-lived radioisotopes, such as Fe (iron) and Al (aluminum), offer unique signs of active nucleosynthesis in our galaxy. There is a long-standing discrepancy between the observed Fe/Al ratio by γ-ray telescopes and predictions from supernova models.
View Article and Find Full Text PDFStochastic Gravitational Waves from Early Structure Formation.
Phys Rev Lett
September 2024
Center for Theoretical Physics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA.
Early matter-dominated eras (EMDEs) are a natural feature arising in many models of the early Universe and can generate a stochastic gravitational wave background (SGWB) during the transition from an EMDE to the radiation-dominated universe required by the time of big bang nucleosynthesis. While there are calculations of the SGWB generated in the linear regime, no detailed study has been made of the nonlinear regime. We perform the first comprehensive calculation of gravitational wave (GW) production in EMDEs that are long enough that density contrasts grow to exceed unity, using a hybrid N-body and lattice simulation to study GW production from both a metastable matter species and the radiation produced in its decay.
View Article and Find Full Text PDFCosmology and fundamental physics with the ELT-ANDES spectrograph.
Exp Astron (Dordr)
February 2024
INAF-Osservatorio Astronomico di Brera, via E. Bianchi 46, 23807 Merate, Italy.
State-of-the-art 19th century spectroscopy led to the discovery of quantum mechanics, and 20th century spectroscopy led to the confirmation of quantum electrodynamics. State-of-the-art 21st century astrophysical spectrographs, especially ANDES at ESO's ELT, have another opportunity to play a key role in the search for, and characterization of, the new physics which is known to be out there, waiting to be discovered. We rely on detailed simulations and forecast techniques to discuss four important examples of this point: big bang nucleosynthesis, the evolution of the cosmic microwave background temperature, tests of the universality of physical laws, and a real-time model-independent mapping of the expansion history of the universe (also known as the redshift drift).
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