Indication for Dual Periodic Signatures in PKS 0805-07 from Multi-technique Time Series Analysis
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| Format: | Preprint |
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2025
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| _version_ | 1866911221777694720 |
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| author | Akbar, Sikandar Shah, Zahir Misra, Ranjeev Boked, Sajad Iqbal, Naseer |
| author_facet | Akbar, Sikandar Shah, Zahir Misra, Ranjeev Boked, Sajad Iqbal, Naseer |
| contents | We report the identification of two statistically significant quasi-periodic oscillations in the weekly binned $γ$-ray light curve of the flat-spectrum radio quasar PKS 0805$-$07, observed by Fermi-LAT over the period MJD 59047.5-59740.5. By applying a suite of complementary time-series analysis techniques, we identify periodic signatures at approximately 255 and 112 days. These techniques include the Lomb-Scargle periodogram (LSP), Weighted Wavelet Z-transform (WWZ), REDFIT, Date-Compensated Discrete Fourier Transform (DCDFT), Phase Dispersion Minimization (PDM), and the String-length method. The reliability of these signals is supported by high local significance (> 99) in all methods and reinforced through phase-folding. Model selection using the Akaike Information Criterion (AIC) and Bayesian Information Criterion (BIC) strongly supports a two-component periodic model. The detection of dual QPOs is rare among blazars and suggests complex variability mechanisms. Although a binary supermassive black hole (SMBH) scenario could be considered given the sources high redshift (z = 1.837), the short periodicities are difficult to reconcile with orbital motion unless invoking extreme parameters. Double-sine model fitting reveals that the oscillatory components have comparable amplitudes but are out of phase, suggesting a potential beating phenomenon due to interference. This amplitude-modulated variability is consistent with a geometric origin, most plausibly jet precession driven by Lense-Thirring torques, superimposed with a secondary process such as polar jet oscillation. Doppler factor modulation arising from these effects can account for the observed flux variations without requiring an unrealistically compact binary. |
| format | Preprint |
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arxiv_https___arxiv_org_abs_2506_09602 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | Indication for Dual Periodic Signatures in PKS 0805-07 from Multi-technique Time Series Analysis Akbar, Sikandar Shah, Zahir Misra, Ranjeev Boked, Sajad Iqbal, Naseer High Energy Astrophysical Phenomena We report the identification of two statistically significant quasi-periodic oscillations in the weekly binned $γ$-ray light curve of the flat-spectrum radio quasar PKS 0805$-$07, observed by Fermi-LAT over the period MJD 59047.5-59740.5. By applying a suite of complementary time-series analysis techniques, we identify periodic signatures at approximately 255 and 112 days. These techniques include the Lomb-Scargle periodogram (LSP), Weighted Wavelet Z-transform (WWZ), REDFIT, Date-Compensated Discrete Fourier Transform (DCDFT), Phase Dispersion Minimization (PDM), and the String-length method. The reliability of these signals is supported by high local significance (> 99) in all methods and reinforced through phase-folding. Model selection using the Akaike Information Criterion (AIC) and Bayesian Information Criterion (BIC) strongly supports a two-component periodic model. The detection of dual QPOs is rare among blazars and suggests complex variability mechanisms. Although a binary supermassive black hole (SMBH) scenario could be considered given the sources high redshift (z = 1.837), the short periodicities are difficult to reconcile with orbital motion unless invoking extreme parameters. Double-sine model fitting reveals that the oscillatory components have comparable amplitudes but are out of phase, suggesting a potential beating phenomenon due to interference. This amplitude-modulated variability is consistent with a geometric origin, most plausibly jet precession driven by Lense-Thirring torques, superimposed with a secondary process such as polar jet oscillation. Doppler factor modulation arising from these effects can account for the observed flux variations without requiring an unrealistically compact binary. |
| title | Indication for Dual Periodic Signatures in PKS 0805-07 from Multi-technique Time Series Analysis |
| topic | High Energy Astrophysical Phenomena |
| url | https://arxiv.org/abs/2506.09602 |