Cosmological evolution of quasar radio emission in the view of
  multifractality
  Variations in scaling behavior in the flux and emissions of distant
astronomical sources with respect to their cosmic time are important l
phenomena that can provide valuable information about the dynamics within the
sources and their cosmological evolution with time. Different studies have been
applying linear analysis to understand and model quasars' light curves. Here,
we study the multifractal behavior of selected quasars' radio emissions in
their observed frame (at 22 and 37 GHz bands) and and their rest frame. To this
end, we apply the wavelet transform-based multifractal analysis formalism
called wavelet transform modulus maxima. In addition, we verify whether the
autoregressive integrated moving average (ARIMA) models fit our data or not. In
our work, we observe strong multifractal behavior for all the sources.
Additionally, we find that the degree of multifractality is strongly similar
for each source and significantly different between sources at 22 and 37 GHz.
This similarity implies that the two frequencies have the same radiation region
and mechanism, whereas the difference indicates that the sources have
intrinsically different dynamics. Furthermore, we show that the degree of
multifractality is the same in the observed and rest frames of the quasars,
i.e., multifractality is an intrinsic property of radio quasars. Finally, we
show that the ARIMA models fit the 3C 345 quasar at 22 GHz and partially fit
most of the time series with the exception of the 3C 273 and 3C 279 quasars at
37 GHz, for which the models are found to be inadequate.
