Journal Article

PUBDB-2025-04936

http://join2-wiki.gsi.de/foswiki/pub/Main/Artwork/join2_logo100x88.png Search for periodic variability in γ-ray blazars Using Fermi -LAT

Peñil, P. (Corresponding author) ; Ajello, M. ; Buson, S. (Corresponding author)DESY* ; Domínguez, A. ; Westernacher-Schneider, J. R. ; Rico, A. ; Adhikari, S. ; Zrake, J.

2025
Oxford Univ. Press Oxford

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Please use a persistent id in citations: doi:10.1093/mnras/staf1108  doi:10.3204/PUBDB-2025-04936

Abstract: Blazars are known to exhibit variability across a broad range of time-scales. This behaviour can include periodicity in theirγ -ray emission, whose clear detection remains an ongoing challenge, partly due to the inherent stochasticity of the processesinvolved and also the lack of adequately well-sampled light curves. In this study, we perform a systematic search for periodicityin a selected sample of 24 γ -ray blazars using twelve years of Fermi-LAT data. The sample comprises the most promisingcandidates selected from a previous study, extending the light curves by three additional years, expanding the analysed energyrange from >1 to >0.1 GeV to improve photon statistics, and enhancing the time-series analysis methodology. We incorporateupper-limit flux points in the analysis rather than discarding them, thereby preserving the temporal structure in the light curves. Asuite of seven complementary time-series analysis methods is employed to ensure statistical robustness, including autoregressivemodels, representing a methodological advancement over the prior work. A further improvement is the explicit estimation of thelook-elsewhere effect, which allows us to assess the global significance of any detected signals. The study is also supported byadditional statistical treatments employed to minimize false detections and strengthen the reliability of the results. Our analysisreveals a hint of periodicity in PG 1553+113 with a global significance of ≈ 1.8σ. For the remaining sources in the sample,the re-evaluation of previously reported periodicities indicates that they are statistically consistent with arising from stochasticvariability.

Note: cc-by

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Contributing Institute(s):

1. Gammaastronomie (Z_GA)

Research Program(s):

1. 613 - Matter and Radiation from the Universe (POF4-613) (POF4-613)
2. DFG project G:(GEPRIS)443220636 - FOR 5195: Relativistische Jets in Aktiven Galaxien (443220636) (443220636)
3. MessMapp - Mapping Highly-Energetic Messengers throughout the Universe (949555) (949555)

Experiment(s):

1. No specific instrument

Appears in the scientific report 2025

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