Fermi-LAT Detection of Extended GeV Emission toward the Middle-aged Supernova Remnant G156.2+05.7
Abstract
We analyse 17 years of Fermi-LAT γ-ray data toward the middle-aged supernova remnant (SNR) G156.2+05.7, supplemented by radio and CO observations and by published X-ray constraints. An extended γ-ray source is detected, well described by a 2D Gaussian template (R68 ∼ 0.84∘). This description is preferred over a foreground CO template, whereas the Gaussian and a uniform disc are statistically indistinguishable under the AIC. The spectrum shows evidence for curvature, with a log-parabola preferred over a power law at the ≈ 3.4σ level. Multi-wavelength spectral energy distribution (SED) modelling, under the adopted assumptions, suggests a leptonic--hadronic joint scenario consistent with the data, with the Fermi-LAT spectrum favouring a hadronic contribution over a purely leptonic interpretation. However, the proton-dominated alternative remains competitive, so the partition of the GeV emission is model-dependent. In the adopted leptonic--hadronic model, the electron population accounts for the radio synchrotron emission and a leptonic γ-ray component, while a steep proton population contributes the remaining hadronic γ-rays. Adopting a reference distance d = 2.7 kpc, the fitted electron cutoff (Ee,cut≈ 1.2 TeV) is compatible with the thermal-dominated X-ray emission, while the proton cutoff is fixed by assumption at $1$ TeV. The northeast and southwest quadrants show enhanced γ-ray emission, which may be related to a clumpy or asymmetric surrounding medium. A correspondence with the directions of optical Hα filaments is suggested by the quadrant orientation but is not yet established. No significant long-term flux variability is found, consistent with steady emission from an extended source.
Related
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- Detection of Knots in the Type Iax Supernova Remnant Pa 30
- Detection of knots in the supernova type Iax remnant Pa 30
- Pulsar J1909+0749 and supernova remnant G42.1-0.2. A case of a pulsar that has exited the shell of its associated supernova remnant
- Pulsar J1909+0749 and Supernova Remnant G42.1-0.2: A case of a pulsar that has exited the shell of its associated supernova remnant
BibTeX
@misc{xu2026fermilat,
title = {{Fermi-LAT Detection of Extended GeV Emission toward the Middle-aged Supernova Remnant G156.2+05.7}},
author = {Wei-Liang Xu and Qing-Wen Tang and Long Li},
howpublished = {arXiv},
year = {2026},
month = nov,
doi = {10.48550/arxiv.2611.04227},
eprint = {2611.04227},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2611.04227},
}
RIS
TY - UNPB
TI - Fermi-LAT Detection of Extended GeV Emission toward the Middle-aged Supernova Remnant G156.2+05.7
AU - Wei-Liang Xu
AU - Qing-Wen Tang
AU - Long Li
PY - 2026
DA - 2026/11/03
PB - arXiv
DO - 10.48550/arxiv.2611.04227
UR - https://arxiv.org/abs/2611.04227
AB - We analyse 17 years of Fermi-LAT γ-ray data toward the middle-aged supernova remnant (SNR) G156.2+05.7, supplemented by radio and CO observations and by published X-ray constraints. An extended γ-ray source is detected, well described by a 2D Gaussian template (R_68 ∼ 0.84^∘). This description is preferred over a foreground CO template, whereas the Gaussian and a uniform disc are statistically indistinguishable under the AIC. The spectrum shows evidence for curvature, with a log-parabola preferred over a power law at the ≈ 3.4σ level. Multi-wavelength spectral energy distribution (SED) modelling, under the adopted assumptions, suggests a leptonic--hadronic joint scenario consistent with the data, with the Fermi-LAT spectrum favouring a hadronic contribution over a purely leptonic interpretation. However, the proton-dominated alternative remains competitive, so the partition of the GeV emission is model-dependent. In the adopted leptonic--hadronic model, the electron population accounts for the radio synchrotron emission and a leptonic γ-ray component, while a steep proton population contributes the remaining hadronic γ-rays. Adopting a reference distance d = 2.7 kpc, the fitted electron cutoff (E_e,cut≈ 1.2 TeV) is compatible with the thermal-dominated X-ray emission, while the proton cutoff is fixed by assumption at $1$ TeV. The northeast and southwest quadrants show enhanced γ-ray emission, which may be related to a clumpy or asymmetric surrounding medium. A correspondence with the directions of optical Hα filaments is suggested by the quadrant orientation but is not yet established. No significant long-term flux variability is found, consistent with steady emission from an extended source.
ER -