Faculty Research at Morehead State University


GeV γray Emission Detected by Fermi-LAT Probably Associated with the Thermal Composite Supernova Remnant Kesteven 41 in a Molecular Environment

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Hadronic emission from supernova remnant (SNR)–molecular cloud (MC) association systems has been widely regarded as a probe of shock-accelerated cosmic-ray protons. Here, we report on the detection of a γ-ray emission source with a significance of 24s in 0.2–300 GeV, projected to lie to the northwest of the thermal composite SNR Kesteven 41, using 5.6 years of Fermi-Large Area Telescope (LAT) observation data. No significant long-term variability in the energy range 0.2–300 GeV is detected around this source. The 3s error circle, 0. 09 in radius, covers the 1720 MHz OH maser and is essentially consistent with the location of the VLSR 50 km s ~ - -1 MC with which the SNR interacts. The source emission has an exponential cutoff power-law spectrum with a photon index of 1.9 ± 0.1 and a cutoff energy of 4.0 0.9 GeV  , and the corresponding 0.2–300 GeV luminosity is 1.3 10 erg s ~ ´ 36 1 - at a distance of 12 kpc. There is no radio pulsar in the 3s circle responsible for the high γ-ray luminosity. While the inverse Compton scattering scenario would lead to difficulty in the electron energy budget, the source emission can naturally be explained by the hadronic interaction between the relativistic protons accelerated by the shock of SNR Kesteven 41 and the adjacent northwestern MC. In this paper, we present a list of Galactic thermal composite SNRs detected at GeV γ-ray energies by Fermi-LAT.