Optical flux behaviour of a sample of Fermi blazars

TL;DR

This study monitored optical flux variability in a sample of gamma-ray blazars over 13 months, revealing that jet orientation changes may cause observed flux variations.

Contribution

It provides a detailed optical variability analysis of multiple blazars and suggests jet direction changes as a possible cause for flux variations.

Findings

Detected flux variability on multiple time-scales.

Proposed jet orientation change as a variability mechanism.

Observed flux variations consistent with geometric models.

Abstract

Aims: We aim at investigating the time-behaviour of a sample of gamma-ray blazars. We present the results from a 13 month-long optical photometry monitoring campaign of the blazars PKS 0048-097, PKS 0754+100, HB89 0827+243, PKS 0851+202, PKS 1253-055, PKS1510-089, PKS 1749+096, PKS 2230+114 and PKS 2251+158. Methods: We analyse the variability of each object, focusing on different time-scales (long term, short term, and microvariability), in an attempt to achieve a statistical comparison of the results. Results: After applying a geometric model to explain the variability results, we found that it is possible that a slight change in the direction of the jet generates the variations detected in some objects during this campaign.