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Transient QPOs of Fermi-LAT blazars with Linearly Multiplicative Oscillations

P. Penil, J. Otero-Santos, A. Circiello, A. Banerjee, S. Buson, A. Rico, M. Ajello, S. Adhikari

TL;DR

The paper investigates transient γ-ray quasi-periodic oscillations in three blazars using Fermi-LAT data, focusing on multiplicative oscillations whose amplitude varies linearly over time. It combines Singular Spectrum Analysis and Generalized Lomb-Scargle Periodograms to identify QPOs and assesses significance with extensive simulations that model red and Poisson noise. A Doppler-boosting jet model, incorporating a moving plasmoid with linearly evolving amplitude, is employed to interpret the oscillations, with separate fits for rising and falling LC segments. The results suggest MG1 J123931+0443 and PKS 1622$-$253 show QPOs consistent with binary SMBH–induced jet precession, while 4C +31.03 appears more stochastic; however, all findings are tentative and demand further observational support. Overall, the work highlights a plausible link between long-term jet dynamics, Doppler boosting, and episodic QPOs in blazar γ-ray emission, offering a framework to probe binary SMBH systems via high-energy variability.

Abstract

We present a study on the detection and characterization of transient quasi-periodic oscillations (QPOs) in the $γ$-ray emission of blazars 4C +31.03, MG1 J123931+0443, and PKS 1622$-$253. Using light curves derived from \textit{Fermi} Large Area Telescope data, we investigate oscillatory patterns characterized by periodic multiplicative amplitudes that vary linearly over time. By segmenting the light curves into increasing and decreasing trends, we analyze each segment independently, allowing for precise measurements of both the periodicity and long-term variations. To interpret these QPOs, we explore various theoretical scenarios that could explain their origin and underlying physical mechanisms. The variability observed in 4C~+31.03 is more consistent with a stochastic process, whereas the periods estimated for MG1~J123931+0443 and PKS~1622$-$253 align with the precessional dynamics expected from binary supermassive black hole systems. However, the current results remain tentative and do not allow for a definitive conclusion.

Transient QPOs of Fermi-LAT blazars with Linearly Multiplicative Oscillations

TL;DR

The paper investigates transient γ-ray quasi-periodic oscillations in three blazars using Fermi-LAT data, focusing on multiplicative oscillations whose amplitude varies linearly over time. It combines Singular Spectrum Analysis and Generalized Lomb-Scargle Periodograms to identify QPOs and assesses significance with extensive simulations that model red and Poisson noise. A Doppler-boosting jet model, incorporating a moving plasmoid with linearly evolving amplitude, is employed to interpret the oscillations, with separate fits for rising and falling LC segments. The results suggest MG1 J123931+0443 and PKS 1622253 show QPOs consistent with binary SMBH–induced jet precession, while 4C +31.03 appears more stochastic; however, all findings are tentative and demand further observational support. Overall, the work highlights a plausible link between long-term jet dynamics, Doppler boosting, and episodic QPOs in blazar γ-ray emission, offering a framework to probe binary SMBH systems via high-energy variability.

Abstract

We present a study on the detection and characterization of transient quasi-periodic oscillations (QPOs) in the -ray emission of blazars 4C +31.03, MG1 J123931+0443, and PKS 1622253. Using light curves derived from \textit{Fermi} Large Area Telescope data, we investigate oscillatory patterns characterized by periodic multiplicative amplitudes that vary linearly over time. By segmenting the light curves into increasing and decreasing trends, we analyze each segment independently, allowing for precise measurements of both the periodicity and long-term variations. To interpret these QPOs, we explore various theoretical scenarios that could explain their origin and underlying physical mechanisms. The variability observed in 4C~+31.03 is more consistent with a stochastic process, whereas the periods estimated for MG1~J123931+0443 and PKS~1622253 align with the precessional dynamics expected from binary supermassive black hole systems. However, the current results remain tentative and do not allow for a definitive conclusion.

Paper Structure

This paper contains 22 sections, 8 equations, 4 figures, 2 tables.

Table of Contents

  1. Introduction
  2. Source Selection
  3. Characterization of the QPOS
  4. Methods for the Search of QPOs
  5. Test Statistics of the QPOs
  6. Results
  7. Theoretical Models
  8. Accretion Disk-Origin Scenarios
  9. Jet-Origin Scenarios
  10. Magnetohydrodynamic Instabilities
  11. External Jet Agents
  12. Jet Precession
  13. Interpretation
  14. Model expressions
  15. Flux Fit
  16. ...and 7 more sections

Figures (4)

  • Figure 1: Segments of LCs of the blazars presented in Table \ref{['tab:candidates_list']} with signatures of transient QPOs. Top left: 4C +31.03. Top right: MG1 J123931+0443. Bottom: PKS 1622$-$253. These segments are further analyzed in detail in $\S$\ref{['sec:flux_analysis']}.
  • Figure 2: LCs from Figure \ref{['fig:qpos_lcs']}, illustrating individual segments with distinct flux trends. Left: Increasing trends. Right: Decreasing trends. From top to bottom: 4C +31.03, MG1 J123931+0443 and PKS 1622$-$253. The red lines indicate the emission fit based on Equation (\ref{['eq:flux_expression']}). The plot legends display the fit parameters, showing the derived period and linear trend estimated for each segment to optimize the R${^2}$ value. The period and trend values correspond to thoe reported in Table \ref{['tab:fitting_results']}.
  • Figure 3: Jet viewing angle as a function of time. Top left: 4C +31.03; Top right: MG1 J123931+0443; Bottom: PKS 1622$-$253. Grey vertical lines indicate the discontinuity arising from uncertainties in the trend estimation for each segment of the $\gamma$-ray emission. This separation reflects the differing observational segments, where variations in the estimated viewing angle may be attributed to fluctuations in the $\gamma$-ray emission trends. Such discontinuities underscore the sensitivity of the viewing angle to transient changes in jet orientation. The value $\Delta\psi$ quantifies this discontinuity between both segments of the LC.
  • Figure A1: LCs of the blazars presented in Table \ref{['tab:candidates_list']}. Top left: 4C +31.03. Top right: MG1 J123931+0443. Bottom: PKS 1622$-$253.