We study the general physical properties of Fermi blazars using the Fermi fourth source catalog data (4FGL-DR2). The quasi-simultaneous multiwavelength data of Fermi blazars are fitted by using the one-zone leptonic model to obtain some physical parameters, such as jet power, magnetic field, and Doppler factor. We study the distributions of the derived physical parameters as a function of black hole mass and accretion disk luminosity. The main results are as follows. (1) For a standard thin accretion disk, the jet kinetic power of most flat-spectrum radio quasars can be explained by the Blandford-Payne (BP) mechanism. However, the jet kinetic power of most BL Lacertae objects (BL Lacs) cannot be explained by either the Blandford-Znajek mechanism or the BP mechanism. The BL Lacs may have advection-dominated accretion flows surrounding their massive black holes. (2) After excluding the redshift, there is a moderately strong correlation between the jet kinetic power and jet radiation power and the accretion disk luminosity for Fermi blazars. These results confirm a close connection between jet and accretion. The jet kinetic power is slightly larger than the accretion disk luminosity for Fermi blazars. (3) There is a significant correlation between jet kinetic power and gamma-ray luminosity and radio luminosity for Fermi blazars, which suggests that gamma-ray luminosity and radio luminosity can be used to indicate the jet kinetic power.

Cone search capability for table J/ApJS/268/6/table1 (The Fermi 4FGL blazars)