Testing relativistic boost as the cause of gamma-ray quasi-periodic oscillation in a blazar

Understand

The mechanism for producing gamma-ray quasi-periodic oscillation (QPO) in blazar is unknown.

• One possibility is the geometric model, in which without the need for intrinsic quasi-periodic variation, the relativistic Doppler factor changes periodically, resulting in observed gamma-ray QPO.
• We propose a method to test this geometric model.
• We analyze the {\it Fermi}-LAT data of PG 1553+113 spanning from 2008 August until 2018 February.