Relevance of jet magnetic field structure for blazar axionlike particle searches. (arXiv:2011.08123v2 [astro-ph.HE] UPDATED)
<a href="http://arxiv.org/find/astro-ph/1/au:+Davies_J/0/1/0/all/0/1">James Davies</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Meyer_M/0/1/0/all/0/1">Manuel Meyer</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Cotter_G/0/1/0/all/0/1">Garret Cotter</a>
Many theories beyond the Standard Model of particle physics predict the
existence of axionlike particles (ALPs) that mix with photons in the presence
of a magnetic field. One prominent indirect method of searching for ALPs is to
look for irregularities in blazar gamma-ray spectra caused by ALP-photon mixing
in astrophysical magnetic fields. This requires the modelling of magnetic
fields between Earth and the blazar. So far, only very simple models for the
magnetic field in the blazar jet have been used. Here we investigate the
effects of more complicated jet magnetic field configurations on these spectral
irregularities, by imposing a magnetic field structure model onto the jet model
proposed by Potter & Cotter. We simulate gamma-ray spectra of Mrk 501 with ALPs
and fit them to no-ALP spectra, scanning the ALP and B-field configuration
parameter space and show that the jet can be an important mixing region, able
to probe new ALP parameter space around $m_asim$ 1-1000 neV and
$g_{agamma}gtrsim$ $5times10^{-12}$ GeV$^{-1}$. However, reasonable (i.e.
consistent with observation) changes of the magnetic field structure can have a
large effect on the mixing. For jets in highly magnetized clusters, mixing in
the cluster can overpower mixing in the jet. This means that the current
constraints using mixing in the Perseus cluster are still valid.
Many theories beyond the Standard Model of particle physics predict the
existence of axionlike particles (ALPs) that mix with photons in the presence
of a magnetic field. One prominent indirect method of searching for ALPs is to
look for irregularities in blazar gamma-ray spectra caused by ALP-photon mixing
in astrophysical magnetic fields. This requires the modelling of magnetic
fields between Earth and the blazar. So far, only very simple models for the
magnetic field in the blazar jet have been used. Here we investigate the
effects of more complicated jet magnetic field configurations on these spectral
irregularities, by imposing a magnetic field structure model onto the jet model
proposed by Potter & Cotter. We simulate gamma-ray spectra of Mrk 501 with ALPs
and fit them to no-ALP spectra, scanning the ALP and B-field configuration
parameter space and show that the jet can be an important mixing region, able
to probe new ALP parameter space around $m_asim$ 1-1000 neV and
$g_{agamma}gtrsim$ $5times10^{-12}$ GeV$^{-1}$. However, reasonable (i.e.
consistent with observation) changes of the magnetic field structure can have a
large effect on the mixing. For jets in highly magnetized clusters, mixing in
the cluster can overpower mixing in the jet. This means that the current
constraints using mixing in the Perseus cluster are still valid.
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