Gamma-Ray Echo as a Probe of Supernova Neutrino Emission Anisotropy and Long-Baseline Effects
Abstract
During a core-collapse supernova (CCSN), the emitted electron antineutrino (ν̅e) burst initiates inverse beta decay (IBD) in the outer hydrogen layer of the stellar envelope. This leads to the production of a characteristic 511 keV photon signal, termed the Gamma-Ray Echo. The same neutrino burst, when detected on Earth in large neutrino observatories such as Hyper-Kamiokande, will offer information about the ν̅e content of the neutrino flux reaching Earth. In this work, we show that comparing the ν̅e content inferred from the gamma-ray echo with that inferred from terrestrial neutrino observations during a nearby CCSN event can offer a promising probe of large neutrino emission anisotropies and long-baseline propagation effects. In the latter case, the combined SN-Earth observations effectively act as a near-far detector configuration for neutrino propagation over an astrophysical baseline. We find that, for a near-Earth supernova, anisotropies or non-standard propagation effects at the level of tens of percent can be tested using gamma-ray telescopes with effective areas of 𝒪(104) cm2. Therefore, our results motivate the development of the next generation of large effective area gamma-ray telescopes operating in the MeV gap.
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BibTeX
@misc{chauhan2026gammaray,
title = {{Gamma-Ray Echo as a Probe of Supernova Neutrino Emission Anisotropy and Long-Baseline Effects}},
author = {Garv Chauhan and Cecilia Lunardini and Yago Porto},
howpublished = {arXiv},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2609.22806},
eprint = {2609.22806},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2609.22806},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - Gamma-Ray Echo as a Probe of Supernova Neutrino Emission Anisotropy and Long-Baseline Effects
AU - Garv Chauhan
AU - Cecilia Lunardini
AU - Yago Porto
PY - 2026
DA - 2026/09/19
PB - arXiv
DO - 10.48550/arxiv.2609.22806
UR - https://arxiv.org/abs/2609.22806
AB - During a core-collapse supernova (CCSN), the emitted electron antineutrino (ν̅_e) burst initiates inverse beta decay (IBD) in the outer hydrogen layer of the stellar envelope. This leads to the production of a characteristic 511 keV photon signal, termed the Gamma-Ray Echo. The same neutrino burst, when detected on Earth in large neutrino observatories such as Hyper-Kamiokande, will offer information about the ν̅_e content of the neutrino flux reaching Earth. In this work, we show that comparing the ν̅_e content inferred from the gamma-ray echo with that inferred from terrestrial neutrino observations during a nearby CCSN event can offer a promising probe of large neutrino emission anisotropies and long-baseline propagation effects. In the latter case, the combined SN-Earth observations effectively act as a near-far detector configuration for neutrino propagation over an astrophysical baseline. We find that, for a near-Earth supernova, anisotropies or non-standard propagation effects at the level of tens of percent can be tested using gamma-ray telescopes with effective areas of 𝒪(10^4) cm^2. Therefore, our results motivate the development of the next generation of large effective area gamma-ray telescopes operating in the MeV gap.
ER -