Singular Spectrum Analysis of Fermi-LAT Blazar Light Curves: A Systematic Search for Periodicity and Trends in the Time Domain

Abstract

A majority of blazars exhibit variable emission across the entire electromagnetic spectrum, observed over various time scales. In particular, discernible periodic patterns are detected in the $\gamma$-ray light curves of a few blazars, such as PG 1553+113, S5 1044+71, and PKS 0426-380. The presence of trends, flares, and noise complicates periodicity detection, requiring careful analysis to determine whether these patterns arise from emission mechanisms or occur by chance. We employ Singular Spectrum Analysis (SSA) for the first time on data from the Large Area Telescope (LAT) aboard the Fermi Gamma-ray Space Telescope to systematically search for periodicity using 28-day binned light curves. We aim to isolate any potential periodic nature of the emission from trends and noise, reducing uncertainties in revealing periodicity. Additionally, we characterize long-term trends and develop a forecasting algorithm based on SSA to predict future emission behavior. We apply SSA to analyze 494 sources detected by Fermi-LAT, focusing on isolating oscillatory components from trends and noise in their $\gamma$-ray light curves. We compute the Lomb-Scargle Periodogram for oscillatory components extracted by SSA to determine the most significant periods, assessing their local and global significance. Our analysis identifies 46 blazars as potential candidates for quasi-periodic $\gamma$-ray emissions, each with a local significance $\ge 2\sigma$. Notably, 33 exhibit a local significance of $\ge 4\sigma$ (corresponding to a global significance of $\ge 2.2\sigma$). Our findings introduce 25 new $\gamma$-ray candidates, doubling the number of potentially periodic sources. This study provides a foundation for future investigations by identifying promising candidates and their significance in blazar variability.

25 pages, 9 figures, 4 tables; Accepted by A&A; Analysis pipeline available at https://www.ucm.es/blazars/ssa

References in corpus (17)

• Measuring the rotation period distribution of field M-dwarfs with Kepler
• A massive binary black-hole system in OJ287 and a test of general relativity
• A possible close supermassive black-hole binary in a quasar with optical periodicity
• A model for periodic blazars
• The Unanticipated Phenomenology of the Blazar PKS~2131$-$021: A Unique Super-Massive Black Hole Binary Candidate
• Fermi Large Area Telescope Performance After 10 Years Of Operation
• Multi-band light curves from eccentric accreting supermassive black hole binaries
• A search for cyclical sources of gamma-ray emission on the period range from days to years in the Fermi-LAT sky
• Quasi-periodic behaviour in the optical and γ-ray light curves of blazars 3C 66A and B2 1633+38
• Quasi-periodic oscillations in the $\gamma$-ray light curves of bright active galactic nuclei
• Transient Quasi-Periodic Oscillations at $\gamma$-rays in the TeV Blazar PKS 1510-089
• The Physical Origins of the Identified and Still Missing Components of the Warm-Hot Intergalactic Medium: Insights from Deep Surveys in the Field of Blazar 1ES1553+113
• The Role of Strong Magnetic Fields in Stabilizing Highly Luminous, Thin Disks
• Quasi-periodic behaviour in the $\gamma$-ray light curve of the blazar PKS 0405-385
• A Possible 3-Year Quasi-Periodic Oscillation in γ-Ray Emission from the FSRQ S5 1044+71
• Multiple Wavelength Variability and Quasi-Periodic Oscillation of PMN J0948+0022
• Periodic Gamma-ray Modulation of the blazar PG 1553+113 Confirmed by Fermi-LAT and Multi-wavelength Observations

Cited by in corpus (5)

• Coexistence of Chromatic Flares and an Achromatic QPO in the Gamma-ray Blazar PG 1553+113
• Transient QPOs of Fermi-LAT blazars under the Curved Jet Model
• A Systematic Search for Spectral Hardening in Blazar Flares with the Fermi-Large Area Telescope
• Spectral Hardening Revealed by Geometric De-boosting in the Masked Jet of PKS 2155$-$304
• Testing X-ray Periodicity and Long-Term Trend in PG 1553+113 via Targeted Swift-XRT Monitoring