Blazar emissions and their dependance on Doppler factor

	Blazars are a subclass of active galactic nuclei (AGNs) with their relativistic jets pointing towards our line of sight. They are characterized by highly variable emissions across the electromagnetic spectrum across different timescales. The bulk of the blazar emission consists of the non-thermal radiations from the relativistic jets; as such, we expect the jet Doppler factor to play a major role in modulating the emissions. The present work explores the dependance of the blazar variability on Doppler factor by considering two candidate blazar sources, 3C 454.3 (z=0.859) and CTA 102 (z=1.032). A long term radio and optical study of the blazar 3C 454.3 revealed that an inhomogenous curved relativistic jet can successfully explain the long term trends in emissions as well as the correlation between radio and optical emissions. Simultaneous quasi periodic oscillations (QPO) in the gamma-ray and optical emissions from 3C 454.3 and CTA 102 were detected. Both the QPOs are among the first detected multiwaveband QPOs with month--like period. The origin of this QPO could be best explained by a blob moving helically inside a curved relativistic jet. The overall curvature of the jet and the helical motions of blobs contributes to a change in Doppler factor which in turn modulates the emission.