Implications of Bulk Velocity Structures in AGN Jets

TL;DR

This paper models AGN jet spectra considering complex bulk velocity structures, revealing their significant impact on observed spectra and implications for unification models of different AGN classes.

Contribution

It introduces models of AGN jets with continuous velocity structures, analyzing their effects on spectra and unification of AGN types, which was not extensively studied before.

Findings

Spectra differ significantly with velocity structures and viewing angles.

Velocity structures influence unification of BLO and FRI radio galaxies.

EC spectra are less affected by velocity structures than synchrotron and SSC spectra.

Abstract

The synchrotron self-Compton (SSC) models and External Compton (EC) models of AGN jets with continually longitudinal and transverse bulk velocity structures are constructed. The observed spectra show complex and interesting patterns in different velocity structures and viewing angles. These models are used to calculate the synchrotron and inverse Compton spectra of two typical BL Lac objects (BLO) (Mrk 421 and 0716+714) and one Flat Spectrum Radio Quasars (FSRQs) (3c 279), and to discuss the implications of jet bulk velocity structures in unification of the BLO and FR I radio galaxies (FRI). By calculating the synchrotron spectra and SSC spectra of BL Lac object jets with continually bulk velocity structures, we find that the spectra are much different from ones in jets with uniform velocity structure under the increase of viewing angles. The unification of BLO and FRI is less constrained by viewing angles and would be imprinted by velocity structures intrinsic to the jet themselves. By considering the jets with bulk velocity structures constrained by apparent speed, we discuss the velocity structures imprinted on the observed spectra for different viewing angles. We find that the spectra are greatly impacted by longitudinal velocity structures, becasue the volume elements are compressed or expanded. Finally, we present the EC spectra of FSRQs and FR II radio galaxies (FRII) and find that they are weakly affected by velocity structures compared to synchrotron and SSC spectra.