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Main Authors: Siegert, Thomas, Calore, Francesca, Jean, Pierre, Leising, Mark, de Séréville, Nicolas, Share, Gerald H., Tatischeff, Vincent, Wang, Wei, Wu, Meng-Ru
Format: Preprint
Published: 2026
Subjects:
Online Access:https://arxiv.org/abs/2602.04592
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_version_ 1866915774123212800
author Siegert, Thomas
Calore, Francesca
Jean, Pierre
Leising, Mark
de Séréville, Nicolas
Share, Gerald H.
Tatischeff, Vincent
Wang, Wei
Wu, Meng-Ru
author_facet Siegert, Thomas
Calore, Francesca
Jean, Pierre
Leising, Mark
de Séréville, Nicolas
Share, Gerald H.
Tatischeff, Vincent
Wang, Wei
Wu, Meng-Ru
contents The nuclear $γ$-ray lines in the MeV range of the electromagnetic spectrum hold a vast variety of astrophysical, particle-physical, and fundamental physical information that is otherwise extreme difficult to access. MeV $γ$-ray line observations provide the most direct evidence for ongoing nucleosynthesis in galaxies by measuring freshly produced radioactive isotopes from massive stars, supernovae, classical novae, or binary neutron star mergers. Their flux ratios can determine the low-energy cosmic-ray spectrum in different objects and of the Milky Way as a whole. Different phases of the interstellar medium are traced by hot nucleosynthesis ejecta, cooling positrons, or cosmic-ray interactions with molecular clouds. Positron annihilation itself can be considered as an astrophysical messenger as their production and destruction in typical space environments is inevitable. Finally, as-of-yet unknown signatures from beyond standard model physics might have their elusive imprints in $γ$-ray lines. This Chapter gives an overview of historical $γ$-ray line measurements, newest results, and open questions that may only be solved by a new generation of MeV telescopes.
format Preprint
id arxiv_https___arxiv_org_abs_2602_04592
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle $γ$-Ray Lines -- Signatures of Nucleosynthesis, Cosmic Rays, Positron Annihilation, and Fundamental Physics
Siegert, Thomas
Calore, Francesca
Jean, Pierre
Leising, Mark
de Séréville, Nicolas
Share, Gerald H.
Tatischeff, Vincent
Wang, Wei
Wu, Meng-Ru
High Energy Astrophysical Phenomena
Astrophysics of Galaxies
Space Physics
The nuclear $γ$-ray lines in the MeV range of the electromagnetic spectrum hold a vast variety of astrophysical, particle-physical, and fundamental physical information that is otherwise extreme difficult to access. MeV $γ$-ray line observations provide the most direct evidence for ongoing nucleosynthesis in galaxies by measuring freshly produced radioactive isotopes from massive stars, supernovae, classical novae, or binary neutron star mergers. Their flux ratios can determine the low-energy cosmic-ray spectrum in different objects and of the Milky Way as a whole. Different phases of the interstellar medium are traced by hot nucleosynthesis ejecta, cooling positrons, or cosmic-ray interactions with molecular clouds. Positron annihilation itself can be considered as an astrophysical messenger as their production and destruction in typical space environments is inevitable. Finally, as-of-yet unknown signatures from beyond standard model physics might have their elusive imprints in $γ$-ray lines. This Chapter gives an overview of historical $γ$-ray line measurements, newest results, and open questions that may only be solved by a new generation of MeV telescopes.
title $γ$-Ray Lines -- Signatures of Nucleosynthesis, Cosmic Rays, Positron Annihilation, and Fundamental Physics
topic High Energy Astrophysical Phenomena
Astrophysics of Galaxies
Space Physics
url https://arxiv.org/abs/2602.04592