http://arxiv.org/abs/2209.14214
We propose that the interaction between the axion-like particles (ALPs) and photons can be a possible origin of the optical circular polarization (CP) in blazars. The non-detection of the optical CP at the level of $0.1\%$ can be used to place a constraint on the ALP-photon coupling $g_{a\gamma}\cdot B_\mathrm{T0}\lesssim7.9\times10^{-12}~\mathrm{G\cdot GeV}^{-1}$ for $m_{a}\lesssim 10^{-13}~\mathrm{eV}$, which depends on the magnetic field model of the blazar jet. This constraint would be stringent for the blazar models with a large magnetic field strength, such as hadronic radiation models. We also perform an analysis for the possible observations of the optical CP in two blazars, and find that they could be explained by the ALP-photon coupling of $\mathcal{O}(10^{-12})~\mathrm{GeV}^{-1}$. As an outlook, our analysis can be improved by further researches on the radiation models of blazars and high-precision simultaneous measurements of the optical linear polarization and CP.
R. Yao, X. Bi, J. Wang, et. al.
Thu, 29 Sep 22
60/70
Comments: 15 pages, 9 figures, 4 tables