Limits on axion-like particles from Mrk 421 with 4.5-years period observations by ARGO-YBJ and Fermi-LAT. (arXiv:2008.09464v2 [astro-ph.HE] UPDATED)

Limits on axion-like particles from Mrk 421 with 4.5-years period observations by ARGO-YBJ and Fermi-LAT. (arXiv:2008.09464v2 [astro-ph.HE] UPDATED)
<a href="http://arxiv.org/find/astro-ph/1/au:+Li_H/0/1/0/all/0/1">Hai-Jun Li</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Guo_J/0/1/0/all/0/1">Jun-Guang Guo</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:+Lin_S/0/1/0/all/0/1">Su-Jie Lin</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Yin_P/0/1/0/all/0/1">Peng-Fei Yin</a>

In this work, we investigate the axion-like particle (ALP)-photon oscillation
effect in the spectra of the blazar Markarian 421 (Mrk 421) using 4.5 years of
the ARGO-YBJ and Fermi-LAT data. These data are collected during the common
operation time, which cover ten activity phases of Mrk 421. No significant
ALP-photon oscillation effect is confirmed. Only the observations of three
phases can be individually used to set the $95%$ $rm C.L.$ constraint on the
ALP parameter space. However, the constraint can be significantly improved if
the analyses for the observations of ten phases are combined. We find that the
Mrk 421 observations of ARGO-YBJ and Fermi-LAT have excluded the ALP parameter
region with the ALP-photon coupling of $g_{agamma} gtrsim 3 times 10^{-11}$
$rm GeV^{-1}$ for the ALP mass of $sim 3times 10^{-10}$ eV $lesssim m_a
lesssim 2times 10^{-8}$ eV.

In this work, we investigate the axion-like particle (ALP)-photon oscillation
effect in the spectra of the blazar Markarian 421 (Mrk 421) using 4.5 years of
the ARGO-YBJ and Fermi-LAT data. These data are collected during the common
operation time, which cover ten activity phases of Mrk 421. No significant
ALP-photon oscillation effect is confirmed. Only the observations of three
phases can be individually used to set the $95%$ $rm C.L.$ constraint on the
ALP parameter space. However, the constraint can be significantly improved if
the analyses for the observations of ten phases are combined. We find that the
Mrk 421 observations of ARGO-YBJ and Fermi-LAT have excluded the ALP parameter
region with the ALP-photon coupling of $g_{agamma} gtrsim 3 times 10^{-11}$
$rm GeV^{-1}$ for the ALP mass of $sim 3times 10^{-10}$ eV $lesssim m_a
lesssim 2times 10^{-8}$ eV.

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