Galactic diffuse gamma-ray emission from GeV to PeV energies in light of up-to-date cosmic ray measurements. (arXiv:2305.06948v1 [astro-ph.HE])
<a href="http://arxiv.org/find/astro-ph/1/au:+Zhang_R/0/1/0/all/0/1">Rui Zhang</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Huang_X/0/1/0/all/0/1">Xiaoyuan Huang</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Xu_Z/0/1/0/all/0/1">Zhi-Hui Xu</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Zhao_S/0/1/0/all/0/1">Shiping Zhao</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Yuan_Q/0/1/0/all/0/1">Qiang Yuan</a>

The diffuse gamma-ray emission between 10 and 1000 TeV from the Galactic
plane was recently measured precisely by the Large High Altitude Air Shower
Observatory (LHAASO), which is very useful in constraining the propagation and
interaction of cosmic rays in the Milky Way. On the other hand, new
measurements of CR spectra reach a very high precision up to 100 TeV energies,
revealing multiple spectral structures of various species. In this work, we
confront the model prediction of the diffuse gamma-ray emission, based on
up-to-date measurements of the local cosmic ray spectra and simplified
propagation setup, with the measurements of diffuse gamma-rays. To better
constrain the low-energy part of the model, we analyze Fermi-LAT data to
extract the diffuse emission between 1 and 500 GeV from the same sky regions of
LHAASO. Compared with the prediction, we find that clear excesses between
several GeV and ~60 TeV of the diffuse emission exist. Possible reasons to
explain the excesses may include unresolved sources or more complicated
propagation models. We illustrate that an exponential-cutoff-power-law
component with an index of -2.40 and cutoff energy of ~30 TeV is able to
account for such excesses.

The diffuse gamma-ray emission between 10 and 1000 TeV from the Galactic
plane was recently measured precisely by the Large High Altitude Air Shower
Observatory (LHAASO), which is very useful in constraining the propagation and
interaction of cosmic rays in the Milky Way. On the other hand, new
measurements of CR spectra reach a very high precision up to 100 TeV energies,
revealing multiple spectral structures of various species. In this work, we
confront the model prediction of the diffuse gamma-ray emission, based on
up-to-date measurements of the local cosmic ray spectra and simplified
propagation setup, with the measurements of diffuse gamma-rays. To better
constrain the low-energy part of the model, we analyze Fermi-LAT data to
extract the diffuse emission between 1 and 500 GeV from the same sky regions of
LHAASO. Compared with the prediction, we find that clear excesses between
several GeV and ~60 TeV of the diffuse emission exist. Possible reasons to
explain the excesses may include unresolved sources or more complicated
propagation models. We illustrate that an exponential-cutoff-power-law
component with an index of -2.40 and cutoff energy of ~30 TeV is able to
account for such excesses.

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