The Physical Properties of Fermi-4LAC Flat Spectrum Radio Quasars

Abstract

Abstract In this work, we collect quasi-simultaneous infrared, optical, X-ray and γ-ray data of 60 Fermi fourth LAT AGN catalog (4LAC) flat spectrum radio quasars (FSRQs). In the framework of the conventional one-zone leptonic model, we investigate the physical properties of Fermi-4LAC FSRQs’ jets by modeling their quasi-simultaneous spectral energy distributions (SEDs). Our main results are summarized as follows. (1) There is a linear correlation between synchrotron peak frequency and curvature of the electron energy distribution. As suggested by previous works, the slope of the best linear fitting equation of this correlation is consistent with statistic acceleration that needs a fluctuation of fractional acceleration gain. (2) The γ-ray dissipation regions are located at the range from 0.1 to 10 pc away from the supermassive black hole, and located outside the broad-line region and within the dusty torus. (3) A size relation P e (the kinetic power carried in relativistic electrons) ∼P B (Poynting flux) ≤P r (the radiative power) <P p (the kinetic power in cold protons) is found in our modeling. Among them, P e ∼ P B suggests that SEDs of almost all FSRQs with parameters are close to equipartition between the magnetic field and the relativistic electrons. The P e < P r suggest that the most energy of the relativistic electrons are dissipated by EC radiation for FSRQs. (4) There is an anticorrelation between the peak energy of SEDs (γ peak) and the jet power (P jet), which is consistent with the blazar sequence.