Optical circular polarization induced by axionlike particles in blazars. (arXiv:2209.14214v3 [astro-ph.HE] UPDATED)

Optical circular polarization induced by axionlike particles in blazars. (arXiv:2209.14214v3 [astro-ph.HE] UPDATED)
<a href="http://arxiv.org/find/astro-ph/1/au:+Yao_R/0/1/0/all/0/1">Run-Min Yao</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Bi_X/0/1/0/all/0/1">Xiao-Jun Bi</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Wang_J/0/1/0/all/0/1">Jin-Wei Wang</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Yin_P/0/1/0/all/0/1">Peng-Fei Yin</a>

We propose that the interaction between the axionlike particles (ALPs) and
photons can be a possible origin of optical circular polarization (CP) in
blazars. Given that there is no definite detection of optical CP at $sim0.1%$
level, a rough limit on ALP-photon coupling can be obtained, specifically
$g_{agamma}cdot B_mathrm{T0}lesssim7.9times10^{-12}~mathrm{Gcdot
GeV}^{-1}$ for $m_{a}lesssim 10^{-13}~mathrm{eV}$, depending on the magnetic
field configuration of the blazar jet. Obviously, for the blazar models with a
larger magnetic field strength, such as hadronic radiation models, this
constraint could be more stringent. We also perform a dedicated analysis of the
tentative observations of optical CP in two blazars, namely 3C 66A and OJ 287,
and we find that these observations could be explained by the ALP-photon mixing
with $g_{agamma} sim 10^{-11}~mathrm{GeV}^{-1}$. As an outlook, our analysis
can be improved by further research on the radiation models of blazars and
high-precision joint measurements of optical CP and linear polarization.

We propose that the interaction between the axionlike particles (ALPs) and
photons can be a possible origin of optical circular polarization (CP) in
blazars. Given that there is no definite detection of optical CP at $sim0.1%$
level, a rough limit on ALP-photon coupling can be obtained, specifically
$g_{agamma}cdot B_mathrm{T0}lesssim7.9times10^{-12}~mathrm{Gcdot
GeV}^{-1}$ for $m_{a}lesssim 10^{-13}~mathrm{eV}$, depending on the magnetic
field configuration of the blazar jet. Obviously, for the blazar models with a
larger magnetic field strength, such as hadronic radiation models, this
constraint could be more stringent. We also perform a dedicated analysis of the
tentative observations of optical CP in two blazars, namely 3C 66A and OJ 287,
and we find that these observations could be explained by the ALP-photon mixing
with $g_{agamma} sim 10^{-11}~mathrm{GeV}^{-1}$. As an outlook, our analysis
can be improved by further research on the radiation models of blazars and
high-precision joint measurements of optical CP and linear polarization.

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