A comprehensive view of PKS 2155-304 from 2008 to 2023 through a multi-epoch modeling of its spectral energy distributions
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| Format: | Preprint |
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2025
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| _version_ | 1866916950020456448 |
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| author | Harutyunyan, G. Sahakyan, N. Bégué, D. Khachatryan, M. |
| author_facet | Harutyunyan, G. Sahakyan, N. Bégué, D. Khachatryan, M. |
| contents | We present a detailed investigation of the temporal and spectral evolution of the emission from the blazar PKS 2155-304, a high-synchrotron-peaked (HSP) blazar. Using $γ$-ray, X-ray, optical/UV, and infrared data assembled from the Markarian Multiwavelength Data Center, we constructed multi-band light curves and temporally resolved spectral energy distributions (SEDs) of PKS 2155-304 to probe the origin of its emission. The light curves show significant variability, with fractional variability peaking at 0.75 in X-rays, 0.4 in the optical/UV, and 0.65 in $γ$-ray band-consistent with expectations for HSPs. Segmenting the $γ$-ray light curve with Bayesian blocks, we defined 253 time-resolved epochs with adequate multi-band coverage and categorized them into quiescent states (QS), multiwavelength flares (MWF), $γ$-ray flares ($γ$F), X-ray flares (XF), and optical/UV flares (OUF). Each SED is modeled within a synchrotron self-Compton (SSC) framework that self-consistently evolves particle injection and cooling; a neural-network surrogate is used to accelerate parameter inference. Kolmogorov-Smirnov tests reveal state-dependent parameter variations relative to QS: (i) during MWF, the magnetic field B, electron luminosity $L_{e}$, maximum electron Lorentz factor $γ_{max}$, and Doppler factor $δ$ differ significantly; (ii) during $γ$F, a harder electron index p is estimated; (iii) XF shows higher B and $γ_{max}$ with a more compact emitting region; and (IV) during OUF, changes in B, $L_{e}$, $γ_{max}$, $δ$, and p are found while the emitting-zone size remains approximately constant. The jet power is electron-dominated (magnetic-to-electron power ratio $η_{B}\simeq0.09-0.17$), with $η_{B}$ rising during XF. These results suggest that variations in acceleration efficiency and magnetization drive band-dependent flaring in PKS 2155-304. |
| format | Preprint |
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arxiv_https___arxiv_org_abs_2509_11827 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | A comprehensive view of PKS 2155-304 from 2008 to 2023 through a multi-epoch modeling of its spectral energy distributions Harutyunyan, G. Sahakyan, N. Bégué, D. Khachatryan, M. High Energy Astrophysical Phenomena Astrophysics of Galaxies We present a detailed investigation of the temporal and spectral evolution of the emission from the blazar PKS 2155-304, a high-synchrotron-peaked (HSP) blazar. Using $γ$-ray, X-ray, optical/UV, and infrared data assembled from the Markarian Multiwavelength Data Center, we constructed multi-band light curves and temporally resolved spectral energy distributions (SEDs) of PKS 2155-304 to probe the origin of its emission. The light curves show significant variability, with fractional variability peaking at 0.75 in X-rays, 0.4 in the optical/UV, and 0.65 in $γ$-ray band-consistent with expectations for HSPs. Segmenting the $γ$-ray light curve with Bayesian blocks, we defined 253 time-resolved epochs with adequate multi-band coverage and categorized them into quiescent states (QS), multiwavelength flares (MWF), $γ$-ray flares ($γ$F), X-ray flares (XF), and optical/UV flares (OUF). Each SED is modeled within a synchrotron self-Compton (SSC) framework that self-consistently evolves particle injection and cooling; a neural-network surrogate is used to accelerate parameter inference. Kolmogorov-Smirnov tests reveal state-dependent parameter variations relative to QS: (i) during MWF, the magnetic field B, electron luminosity $L_{e}$, maximum electron Lorentz factor $γ_{max}$, and Doppler factor $δ$ differ significantly; (ii) during $γ$F, a harder electron index p is estimated; (iii) XF shows higher B and $γ_{max}$ with a more compact emitting region; and (IV) during OUF, changes in B, $L_{e}$, $γ_{max}$, $δ$, and p are found while the emitting-zone size remains approximately constant. The jet power is electron-dominated (magnetic-to-electron power ratio $η_{B}\simeq0.09-0.17$), with $η_{B}$ rising during XF. These results suggest that variations in acceleration efficiency and magnetization drive band-dependent flaring in PKS 2155-304. |
| title | A comprehensive view of PKS 2155-304 from 2008 to 2023 through a multi-epoch modeling of its spectral energy distributions |
| topic | High Energy Astrophysical Phenomena Astrophysics of Galaxies |
| url | https://arxiv.org/abs/2509.11827 |