Gamma-ray and optical oscillations of 0716+714, MRK 421, and BL Lacertae
Abstract
We examine the 2008-2016 γ-ray and optical light curves of three bright BL Lac objects, 0716+714, MRK 421, BL Lac, which exhibit large structured variability. We searched for periodicities by using a fully Bayesian approach. For two out of three sources investigated, no significant periodic variability was found. In the case of BL Lac, we detected a periodicity of 680 days. Although the signal related to this is modest, the coincidence of the periods in both gamma and optical bands is indicative of a physical relevance. Taking into consideration previous literature results, possibly related γ-ray and optical periodicities of about one year time scale are proposed in four bright γ-ray blazars out of the ten examined in detail. Compared with results from periodicity search of optical archives of quasars, the presence of quasi-periodicities in blazars may be more frequent by a large factor. This suggests the intriguing possibility that the basic conditions for their observability are related to the relativistic jet in the observer direction, but the overall picture remains uncertain.
- Publication:
-
Astronomy and Astrophysics
- Pub Date:
- April 2017
- DOI:
- 10.1051/0004-6361/201630288
- arXiv:
- arXiv:1701.04454
- Bibcode:
- 2017A&A...600A.132S
- Keywords:
-
- gamma rays: galaxies;
- BL Lacertae objects: general;
- galaxies: jets;
- BL Lacertae objects: individual: PKS 0716+71;
- BL Lacertae objects: individual: MRK 421;
- BL Lacertae objects: individual: BL Lac;
- Astrophysics - High Energy Astrophysical Phenomena
- E-Print:
- 7 pages, 8 figure