Modelling the γ -ray variability of 3C 273

Abstract

We investigate the MeV-GeV γ-ray outbursts in 3C 273 using a time-dependent one-zone synchrotron self-Compton model.In this model, electrons are accelerated to extrarelativistic energy, through stochastic particle acceleration, and evolvewith time. Non-thermal photons are produced by both synchrotron and inverse Compton scattering of synchrotron photons. Moreover, non-thermal photons during a quiescent state are produced by relativistic electrons in the steady state, and those during an outburst are produced by electrons whose injection rate is changed at some time interval. We apply the model to two exceptionally luminous γ-ray outbursts from 3C 273 observed by the Fermi Large Area Telescope in 2009 September. We obtain the multiwavelength spectra during both the quiescent and outburst states. Our results show that the time-dependent properties of outbursts can be reproduced by adopting the appropriate injection rate function of the electron population. © 2013 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society.