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Paper: Probing Low-energy Cosmic Rays With Observations of the Neutral Iron Line in the W51 Complex
Volume: 528, New Horizons in Galactic Center Astronomy and Beyond
Page: 445
Authors: Shimaguchi, A.; Nobukawa, K. K.; Yamauchi, S.
Abstract: Galactic cosmic rays are thought to be accelerated by shocks in supernova remnants. Low-energy cosmic rays (LECRs) effectively ionize neutral iron atoms and then the neutral iron line at 6.4 keV is emitted. Enhancement of the neutral iron line due to LECR protons was observed near the Galactic center. In this paper, we report discovery of the neutral iron line from the middle-aged supernova remnant W51C and its vicinity. The observed neutral iron is likely to be generated by low-energy cosmic rays. The proton energy density is estimated to be ∼30 eV cm–3, which is higher than the canonical value.
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