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arXiv · 2007.04821

On the gamma-ray emission of W44 and its surroundings

Giada Peron·Felix Aharonian·Sabrina Casanova·Roberta Zanin·Carlo Romoli
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Abstract

We present the analysis of 9.7 years Fermi-LAT data of the middle-aged supernova remnant W44 and the massive molecular gas complex that surrounds it. We derived a high-quality spectral energy distribution of gamma-radiation of the shell over three decades. The very hard spectrum below 1 GeV supports the earlier claims regarding the hadronic origin of radiation. We also confirm the presence of two extended $\gamma$-ray structures located at two opposite edges of the remnant along its major axis. Based on the high-resolution gas maps, we demonstrate that the gamma-ray structures are caused by the enhanced cosmic-ray density rather than the gradient of the gas distribution. We argue that the revealed cosmic-ray "clouds" suggest an anisotropic character of the escape of high-energy particles from the shell along the magnetic field of the remnant.

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Giada Peron, Felix Aharonian, Sabrina Casanova, Roberta Zanin, Carlo Romoli. 2020-07-09. On the gamma-ray emission of W44 and its surroundings. https://doi.org/10.3847/2041-8213%2Fab93d1

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