Unit:
Κατεύθυνση Αστροφυσική, Αστρονομία και Μηχανική (ΒΑΣΙΚΗ ΦΥΣΙΚΗ)Library of the School of Science
Supervisors info:
Απόστολος Μαστιχιάδης Καθηγητής (Επιβλέπων), Νεκτάριος Βλαχάκης Αναπλ. Καθηγητής, Δέσποινα Χατζηδημητρίου Αναπλ. Καθηγήτρια
Original Title:
Μοντελοποίηση Φασμάτων στους Ενεργούς Γαλαξιακούς Πυρήνες
Translated title:
Modelling Non-Thermal Spectra at Active Galactic Nuclei
Summary:
Adopting the hypothesis that the nonthermal emission of blazars is primarily
due to the acceleration
of electrons, we construct a simple leptonic model in order to explain the
Blazar Sequence. The
acceleration process is assumed to be of the first order Fermi type and the
injected electrons and
photons in the emitting region of the blazar are described by spatially
averaged kinetic equations.
According to the leptonic scenario, the spectral energy distributions of
blazars have two basic
components: a low frequency component, peaking in the optical through X-rays,
from synchrotron
emission; and a high frequency one, peaking in the γ rays, probably originating
from Compton
scattering of some seed photon source, either internal (synchrotron
self-Compton) and/or external to
the jet (external Compton). We find an adequate description of the Blazar
Sequence by assuming a
wind density profile of the form n 1/r. Higher luminosity objects have higher
accretion rates,
higher optical thicknesses of the wind to Compton scattering and thus higher
external photon fields
than the lower luminosity ones. Therefore, we present indicative Blazar
Sequence models which
reproduce the basic observational trends just by varying one parameter, namely
the mass accretion
rate.
Keywords:
Active Galactic Nuclei, Blazar Sequence, Leptonic Model, Particles Acceleration, Accretion disks' wind
