Revisiting the analysis of axion-like particles with the Fermi-LAT gamma-ray observation of NGC1275
Ji-Gui Cheng, Y. He, Yun-Feng Liang, Rui-Jing Lu, En‐Wei Liang
Abstract
In this work, we re-analyze the Fermi-LAT observation of NGC 1275 to search for axion-like particle (ALP) effects and constrain ALP parameters. Instead of fitting the observed spectrum with ALP models, we adopt an alternative method for the analysis of this source which calculates the irregularity of the spectrum. With the newly used method, we find no spectral oscillation for the NGC 1275 and rule out couplings gaγ>3×10−12GeV−1 around ALP mass of ma∼1 neV at 95% confidence level, which is more stringent than the previous results. We also show that the constraints can be further improved by combining the observation of PKS 2155-304. We suggest that with more sources taken into account, we could obtain a much wider exclusion region.