Axion effects on gamma-ray spectral irregularities with AGN redshift uncertainty

We investigate the photon-ALP (axion-like particle) oscillation effect on TeV gamma-ray spectral irregularities from the uncertain redshift active galactic nuclei (AGN) VER J0521+211. The gamma-ray spectra are measured by the collaborations Fermi-LAT and VERITAS with the three flux states in 2013 and 2014. We set the combined constraints on the ALP parameter ($m_a, g_{a\gamma}$) space with these states and test the extragalactic background light (EBL) absorption effect on ALP constraints with the four redshift upper limit scenarios of VER J0521+211. The 3$\sigma$ photon-ALP combined constraints set by VER J0521+211 are roughly at $g_{a\gamma} \gtrsim 2.3\times 10^{-11} \rm \, GeV^{-1}$ for $m_a \lesssim 5\times 10^{-8}\, \rm eV$. We find no clear connection between the redshift upper limit scenarios and the photon-ALP constraints.Comment: 6 pages, 5 figure