Low energy γ-ray spectrum of NGC4151

Following the first detection of X-ray emission from the Seyfert galaxy NGC41511, later observations2–4have demonstrated that the X-ray spectrum up to 100 keV may be described by a power law having a differential spectral index 1<α<1.6 with a turnover at low energies caused by photoelectric absorption. Recently the results of an observation of this galaxy in the energy range 25–190 keV (ref. 5) have shown it to have a very hard spectrum with α≅0.9. Here more detailed results of the original observation of NGC4151 (ref. 6) using the MISO telescope are presented.