2024/06/01 by Li, Hai-Jun, Chao, Wei, Zhou, Yu-Feng · 3 citations
#FOS: Physical sciences #High Energy Astrophysical Phenomena (astro-ph.HE) #High Energy Physics - Phenomenology (hep-ph)
paper · doi:10.48550/arxiv.2406.00387
Markarian 421 is a well-known nearby BL Lac blazar at the redshift z=0.031. Many previous works were investigated to constrain the axion-photon coupling from its TeV gamma-ray observations, showing the upper limit on the coupling constant gaγ \lesssim 2.0× 10-11 \rm GeV-1 for the axion mass [5.0×10-10 \rm eV \lesssim ma \lesssim 5.0×10-7 \rm eV]. While in this work, we obtain a more stringent upper limit on the axion-photon coupling from the 1038 days gamma-ray observations of the blazar Markarian 421. The long-term gamma-ray spectra are measured by the collaborations Large Area Telescope on board NASA's Fermi Gamma-ray Space Telescope (Fermi-LAT) and High Altitude Water Cherenkov (HAWC) Gamma-Ray Observatory from 2015 June to 2018 July. We show the best-fit spectral energy distributions (SEDs) of Markarian 421 under the null and axion hypotheses. Then we set the axion-photon limit in the \ma, gaγ\ plane. The 99% \rm C.L. upper limit set by Markarian 421 is gaγ \lesssim 4.0× 10-12 \rm GeV-1 for the axion mass [1.0×10-9 \rm eV \lesssim ma \lesssim 1.0×10-8 \rm eV]. It is the most stringent upper limit in this axion mass region.