# Quasi-Periodicities at Year Time Scales in Blazars

## TL;DR

This study investigates gamma-ray and optical light curves of bright Fermi blazars from 2008 to 2016, identifying potential quasi-periodicities that may be linked to relativistic jets, though the overall understanding remains uncertain.

## Contribution

It provides evidence of quasi-periodicities in blazars across two bands, suggesting a connection to relativistic jets and advancing the understanding of their temporal behavior.

## Key findings

- Possible quasi-periodicities observed in gamma-ray and optical bands.
- Coincidence of periodicities in both bands supports their physical significance.
- Results imply jet orientation influences observability of quasi-periodicities.

## Abstract

We examine the 2008-2016 gamma-ray and optical light curves of a number of bright Fermi blazars. In a fraction of them, the periodograms show possible evidence of quasi-periodicities related in the two bands. This coincidence strengthens their physical meaning. Comparing with results from the periodicity search of quasars, the presence of quasi-periodicities in blazars suggests that the basic condition for its observability is related to the relativistic jet in the observer direction, but the overall picture remains uncertain.