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arXiv · 2608.05809

GeV {\gamma}-ray emission in the star-forming region S140

Li-Nuo Yang·Pak-Hin Thomas Tam
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Abstract

We report the detection of a GeV {\gamma}-ray source in the S140 HII region using 17.75 years of Fermi-LAT data, with a source-detection significance of ~32.1{\sigma} in the 0.1-500 GeV energy band. The emission is significantly extended (AIC evidence ratio above 1 GeV is 2x10^9) and is therefore designated as 4FGL J2220.8+6319e. The {\gamma}-ray emission coincides spatially with a molecular cloud that hosts the massive young stellar object S140 IRS1. Its spectrum is best fitted by a log-parabolic spectrum (TS_cur(LP) = 104.1) and can be reproduced by both hadronic and leptonic models. The jet driven by S140 IRS1 offers a viable particle acceleration site, yielding injection timescales and maximum particle energies consistent with theoretical expectations, whereas stellar winds are energetically disfavored.

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Li-Nuo Yang, Pak-Hin Thomas Tam. 2026-08-06. GeV {\gamma}-ray emission in the star-forming region S140. https://doi.org/10.3847/1538-4357%2Fae9162

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