Constraints on the Composition, Magnetization, and Radiative Efficiency in the Jets of Blazars

Abstract

The composition and energy dissipation in jets are two of the fundamental questions of jet physics that are not fully understood. In this paper, we attempt to constrain the composition, magnetization, and radiative efficiency for blazars with the recently released low-frequency radio catalog of the TIFR GMRT Sky Survey at 150 MHz. The jet power estimated from the low-frequency radio emission is much lower than that derived from spectral energy distribution fitting assuming one proton per electron. Assuming the jet power estimated from low-frequency radio emission is physical, the fraction of electron/positron pairs can be constrained with n pairs / n p  ∼ 10. By comparing the power carried by the magnetic field and radiation with the jet power estimated from the low-frequency radio emission, we find both the relatively high magnetization parameter of σ  ∼ 0.5 and the radiative efficiency of η  ∼ 0.4 in the dissipation region of blazars. These results suggest that magnetic reconnection processes may play an important role in the energy dissipation of blazars. We also explore the connection between these three parameters ( n pairs / n p , σ , and η ) and the black hole mass, disk luminosity, and Eddington ratio. No significant correlation is found, except that σ shows a possible correlation with disk luminosity.