We investigate the evolution of a changing-look blazar (CLB) on long timescales and expect to trace the state change of a CLB. Three morphological types, including a flat spectrum radio quasar (FSRQ) state, transition state, and BL Lacertae (BL Lac) state, are classified according to the criteria proposed by analyzing the relationship between the equivalent width of the emission line and the γ-ray photon spectral index Γγ. The multiwavelength light curves and spectral energy distributions corresponding to different epochs are obtained. The efforts found that Γγ satisfy the relationships with Γγ ≳ 2.2 for the FSRQ state, 2.0 < Γγ < 2.2 for the transition state, and Γγ ≲ 2.0 for the BL Lac state. We apply the criteria to the photon spectrum evolution of CLB OQ 334 during MJD 58678–60387. The evolution is subdivided into five FSRQ states, nine transition states, and four BL Lac states. Moreover, we use the model spectra parameters of each state epoch to test the reliability of subdivided morphological types. The result shows that: (1) the accretion rate parameter is consistent with our earlier research; and (2) there is an increasing trend in the epochs of the BL Lac states, even if there is not an obvious decreasing trend in epochs of the FSRQ states. We issue strong evidence that a CLB is an especial epoch in the evolution of blazars that could be obtained from the oscillation phenomenon in the CLB evolution.

中文翻译：

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变化外观 Blazar OQ 334 进化中的振荡


我们研究了长期时间尺度上 changing-look blazar （CLB） 的演变，并希望追踪 CLB 的状态变化。通过分析发射线等效宽度与γ射线光子光谱指数 Γγ 之间的关系，根据提出的标准对平面光谱类星体 （FSRQ） 态、过渡态和 BL Lacertae （BL Lac） 态三种形态类型进行分类。得到了对应于不同纪元的多波长光曲线和光谱能量分布。研究发现，Γγ 满足 FSRQ 状态的 Γγ ≳ 2.2、过渡态的 2.0 < Γγ < 2.2 和 BL Lac 状态的 Γγ ≲ 2.0 的关系。我们将该标准应用于 MJD 58678-60387 期间 CLB OQ 334 的光子光谱演变。演变细分为 5 个 FSRQ 状态、9 个过渡状态和 4 个 BL Lac 状态。此外，我们使用每个状态 epoch 的模型光谱参数来测试细分形态类型的可靠性。结果表明：（1）吸积率参数与我们早期的研究一致;（2） BL Lac 州的纪元呈上升趋势，即使 FSRQ 州的纪元没有明显的下降趋势。我们发布了强有力的证据表明，CLB 是 blazars 进化的一个特殊时期，可以从 CLB 进化中的振荡现象中获得。