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arXiv · 2112.04875

Spatially decomposed $γ$-ray features surrounding SNR Kes 79 & PSR J1853+0056

Xinbo He·Yudong Cui·Paul K. H. Yeung·P. H. Thomas Tam·Yong Zhang·Yang Chen
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Abstract

There have been substantial improvements on Fermi Large Area Telescope (LAT) data and analysis tools since the last analysis on the mid-aged supernova remnant (SNR) Kes 79 (Auchettl et al. 2014). Recent multi-wavelength studies confirmed its interaction with molecular clouds. About $0.36\degr$ north from Kes 79, a powerful pulsar -- PSR J1853+0056 also deserves our attention. In this work, we analyse the 11.5-year Fermi-LAT data to investigate the $γ$-ray feature in/around this complex region. Our result shows a more significant detection ($\sim$34.8$σ$ in 0.1--50 GeV) for this region. With $\ge$5 GeV data, we detect two extended sources -- Src-N (the brighter one; radius $\approx0.31\degr$) concentrated at the north of the SNR while enclosing PSR J1853+0056, and Src-S (radius $\approx0.58\degr$) concentrated at the south of the SNR. Their spectra have distinct peak energies ($\sim$1.0 GeV for Src-N and $\lesssim$0.5 GeV for Src-S), suggesting different origins for them. In our hadronic model that includes the leaked cosmic-rays (CRs) from the shock-cloud collision, even with extreme values of parameters, SNR Kes 79 can by no means provide enough CRs reaching clouds at Src-N to explain the local GeV spectrum. We propose that the Src-N emission could be predominantly reproduced by a putative pulsar wind nebula (PWN) powered by PSR J1853+0056. On the other hand, our same hadronic model can reproduce a majority of the GeV emission at Src-S with typical values of parameters, while the three known pulsars inside Src-S release a total power that is too low to account for half of its $γ$-ray emission.

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Xinbo He, Yudong Cui, Paul K. H. Yeung, P. H. Thomas Tam, Yong Zhang, Yang Chen. 2022-02-03. Spatially decomposed $γ$-ray features surrounding SNR Kes 79 & PSR J1853+0056. https://doi.org/10.3847/1538-4357%2Fac51d6

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