Gamma-ray emission toward supergiant shells in the Large Magellanic Cloud

@misc{yu2026gammaray,
  title = {{Gamma-ray emission toward supergiant shells in the Large Magellanic Cloud}},
  author = {Qixin Yu and Olaf Reimer and Anita Reimer},
  howpublished = {arXiv},
  year = {2026},
  month = sep,
  doi = {10.48550/arxiv.2609.28164},
  eprint = {2609.28164},
  archivePrefix = {arXiv},
  url = {https://arxiv.org/abs/2609.28164},
  note = {CC BY 4.0},
}

TY  - UNPB
TI  - Gamma-ray emission toward supergiant shells in the Large Magellanic Cloud
AU  - Qixin Yu
AU  - Olaf Reimer
AU  - Anita Reimer
PY  - 2026
DA  - 2026/09/23
PB  - arXiv
DO  - 10.48550/arxiv.2609.28164
UR  - https://arxiv.org/abs/2609.28164
AB  - The Large Magellanic Cloud (LMC), a satellite galaxy of our Milky Way, is considered to be a very good target for investigations of diffuse gamma-ray emission. Observations have shown that diffuse emissions are related to the large- and small-scale structures of the LMC. Particularly, it has been suggested that some of the small-scale bright diffuse emissions coincide with supergiant shells (SGSs) previously identified based on Hα images. We analyzed the gamma-ray emission from the LMC using more than 15 years of observations with the \textit{Fermi} Large Area Telescope in the energy range of 300MeV-300GeV. A dedicated spatial and spectral analysis was made for diffuse emission components of the LMC. Particularly, we evaluated the emissions from SGSs in detail using phenomenological approaches, and we established their corresponding spatial templates for gamma-ray emission. In the analysis of small-scale extended emissions, we detected seven Hα-selected SGSs at a significance of more than 5σ. The emission structure nested inside the SGSs appears to be a non-Gaussian feature and is very likely due to a modulated cosmic-ray distribution by an ensemble of supernova remnant shocks. The spectra of the gamma-ray emission for most SGS regions favor a hadronic origin. For the large-scale diffuse emission from the LMC disk, our results suggest an interplay of hadron- and lepton-induced emission. The cosmic-ray proton energy density derived for bright SGSs is 3-10 times higher than that in the LMC disk. SGS2 was detected to be the most significant emission region among all SGSs. Based on the gamma-ray excess emission we detected in Hα-selected SGSs in the LMC, we estimate that their contribution to the total diffuse gamma-ray emission in the LMC is at a non-negligible 41\% level.
ER  -