A Non-Mainstream Viewpoint on Apparent Superluminal Phenomena in AGN Jet

TL;DR

This paper explores how variations in the group velocity of light near AGN jets could influence observed superluminal motion and Doppler effects, challenging the common assumption that light's group velocity is always equal to c.

Contribution

It re-derives superluminal and Doppler formulas considering variable light group velocity, offering a new perspective on AGN jet observations.

Findings

Group velocity variations can significantly affect apparent superluminal phenomena.

Re-derived formulas show potential deviations from standard models under certain conditions.

Highlights the importance of medium properties around AGN jets in observational interpretations.

Abstract

The group velocity of light in material around the AGN jet is acquiescently one (c as a unit), but this is only a hypothesis. Here, we re-derive apparent superluminal and Doppler formulas for the general case (it is assumed that the group velocity of light in the uniform and isotropic medium around a jet (a beaming model) is not necessarily equal to one, e.g., Araudo et al. (2010) thought that there may be dense clouds around AGN jet base), and show that the group velocity of light close to one could seriously affect apparent superluminal phenomena and Doppler effect in the AGN jet (when the viewing angle and Lorentz factor take some appropriate values).