On the connection of radio and $gamma$-ray emission in blazars. (arXiv:1901.08793v1 [astro-ph.HE])
<a href="http://arxiv.org/find/astro-ph/1/au:+Boula_S/0/1/0/all/0/1">Stella Boula</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Petropoulou_M/0/1/0/all/0/1">Maria Petropoulou</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Mastichiadis_A/0/1/0/all/0/1">Apostolos Mastichiadis</a>
Blazars are a sub-category of radio-loud active galactic nuclei with
relativistic jets pointing towards to the observer. They are well-known for
their non-thermal variable emission, which practically extends over the whole
electromagnetic spectrum. Despite the plethora of multi-wavelength
observations, the issue about the origin of the $gamma$-ray and radio emission
in blazar jets remains unsettled. Here, we construct a parametric leptonic
model for studying the connection between the $gamma$-ray and radio emission
in both steady-state and flaring states of blazars. Assuming that relativistic
electrons are injected continuously at a fixed distance from the black hole, we
numerically study the evolution of their population as it propagates to larger
distances while losing energy due to expansion and radiative cooling. In this
framework, $gamma$-ray photons are naturally produced at small distances (e.g.
$10^{-3}$ pc) when the electrons are still very energetic, whereas the radio
emission is produced at larger distances (e.g. $1$ pc), after the electrons
have cooled and the emitting region has become optically thin to synchrotron
self-absorption due to expansion. We present preliminary results of our
numerical investigation for the steady-state jet emission and the predicted
time lags between $gamma$-rays and radio during flares.
Blazars are a sub-category of radio-loud active galactic nuclei with
relativistic jets pointing towards to the observer. They are well-known for
their non-thermal variable emission, which practically extends over the whole
electromagnetic spectrum. Despite the plethora of multi-wavelength
observations, the issue about the origin of the $gamma$-ray and radio emission
in blazar jets remains unsettled. Here, we construct a parametric leptonic
model for studying the connection between the $gamma$-ray and radio emission
in both steady-state and flaring states of blazars. Assuming that relativistic
electrons are injected continuously at a fixed distance from the black hole, we
numerically study the evolution of their population as it propagates to larger
distances while losing energy due to expansion and radiative cooling. In this
framework, $gamma$-ray photons are naturally produced at small distances (e.g.
$10^{-3}$ pc) when the electrons are still very energetic, whereas the radio
emission is produced at larger distances (e.g. $1$ pc), after the electrons
have cooled and the emitting region has become optically thin to synchrotron
self-absorption due to expansion. We present preliminary results of our
numerical investigation for the steady-state jet emission and the predicted
time lags between $gamma$-rays and radio during flares.
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