Reconcilement of VHE texorpdfstring{$gamma$},-ray/X-ray correlation studies in Mrk 421 and break-down at high fluxes. (arXiv:1901.02454v1 [astro-ph.HE])
<a href="http://arxiv.org/find/astro-ph/1/au:+Gonzalez_M/0/1/0/all/0/1">M. M. González</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Patricelli_B/0/1/0/all/0/1">B. Patricelli</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Fraija_N/0/1/0/all/0/1">N. Fraija</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Garcia_Gonzalez_J/0/1/0/all/0/1">J.A. García-González</a>
Multi-wavelength campaigns have been carried out to study the correlation
between the very high energy (VHE) $gamma$-ray and the X-ray emissions in
blazars but, no conclusive results have been achieved yet. In this paper, we
add Milagro data to the existing VHE $gamma$-ray data from HEGRA-CT1 and
Whipple and test the consistency and robustness of the reported correlation
between VHE $gamma$-ray and X-ray fluxes in Mrk 421. We found that at monthly
time scale the correlation is robust, consistent between instruments and
described as a linear function. Furthermore, most of the fluxes on shorter time
scales are consistent with the correlation within 3 $sigma_A$ even, where
$sigma_A$ is an estimated intrinsic scatter. However, a break-down of the
correlation becomes clearly evident at high states of activity with fluxes $rm
gtrsim 2.5times 10^{-10}, cm^{-2}s^{-1}$ at energies above 400 GeV
independently of the time scale, observational period or instrument, even for
single flares, the X-ray and VHE $gamma$-ray emissions lie on the correlation
until the VHE $gamma$-ray flux reaches values higher than the one mentioned
above. We have interpreted our results within the one-zone synchrotron
self-Compton model. We found that describing a single and unique
$gamma$-ray/X-ray correlation strongly narrows the range of possible values of
the magnetic field $B$ when a constant value of the spectral index along the
correlation is assumed.
Multi-wavelength campaigns have been carried out to study the correlation
between the very high energy (VHE) $gamma$-ray and the X-ray emissions in
blazars but, no conclusive results have been achieved yet. In this paper, we
add Milagro data to the existing VHE $gamma$-ray data from HEGRA-CT1 and
Whipple and test the consistency and robustness of the reported correlation
between VHE $gamma$-ray and X-ray fluxes in Mrk 421. We found that at monthly
time scale the correlation is robust, consistent between instruments and
described as a linear function. Furthermore, most of the fluxes on shorter time
scales are consistent with the correlation within 3 $sigma_A$ even, where
$sigma_A$ is an estimated intrinsic scatter. However, a break-down of the
correlation becomes clearly evident at high states of activity with fluxes $rm
gtrsim 2.5times 10^{-10}, cm^{-2}s^{-1}$ at energies above 400 GeV
independently of the time scale, observational period or instrument, even for
single flares, the X-ray and VHE $gamma$-ray emissions lie on the correlation
until the VHE $gamma$-ray flux reaches values higher than the one mentioned
above. We have interpreted our results within the one-zone synchrotron
self-Compton model. We found that describing a single and unique
$gamma$-ray/X-ray correlation strongly narrows the range of possible values of
the magnetic field $B$ when a constant value of the spectral index along the
correlation is assumed.
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