The Energy Budget in the Jet of High-frequency Peaked BL Lacertae Objects

Abstract

Energy equipartition and the energy budget in the jet are important issues for the radiation mechanism of blazars. Early work predominantly concentrated on flat-spectrum radio quasars and a limited number of BL Lacertae (BL Lac) objects. In this paper, we compile 348 high-frequency peaked BL Lac objects (HBLs) based on the catalog of active galactic nuclei (4LAC-DR3) from Fermi-LAT, and employ JetSet to fit the spectral energy distributions (SEDs) of these HBLs in the framework of the one-zone lepton model. We aim to determine whether the energy budget is reasonable and whether energy equipartition is satisfied in HBLs. The results of the statistical analysis suggest that: (1) SEDs of HBLs can be reproduced well by using the one-zone lepton model; however, it cannot achieve energy equalization, and the relativistic electron energy density is far greater than the magnetic field energy density, U _e ≳ 100 U _B ; (2) the majority of HBLs are located in the t _cool U _Syn ∼ U _B , L _e ∼ L _p > L _B ∼ L _rad , and $\mathrm{log}{\epsilon }_{e}\gt 0.5$ are established. These relations indicate that most of the energy of HBLs is stored in the population of low-energy electrons.

Keywords

• Blazars
• BL Lacertae objects