Multiwavelength Variation Phenomena of PKS 0735+178 on Diverse Timescales
Multiwavelength Variation Phenomena of PKS 0735+178 on Diverse Timescales
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DOI：
10.3847/1538-4357/ac7647
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发表时间：
2022-06
期刊：
影响因子：
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通讯作者：
Y. Fang;Qihang Chen;Yan Zhang;Jianghua Wu
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文献类型：
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作者：
Y. Fang;Qihang Chen;Yan Zhang;Jianghua Wu
BL Lac天体PKS 0735+178在以前的研究中已经显示了一些复杂的多波长变化现象，特别是在它的颜色行为方面。更亮时更蓝、更亮时更红和消色差行为都被发现是PKS 0735+178的可能长期趋势。在这项工作中，我们收集了PKS 0735+178的长期多波长数据，并在日内时间尺度上进行了实时光学监测。在一个晚上检测到日内变异。在较长的时间尺度上，发现R和γ射线带之间可能存在22天的时间滞后。互相关分析的结果显示，在日内和长时间尺度上，各种光学波段之间具有很强的相关性。然而，只有一个温和的相关性之间的长期γ射线和R-波段的光变曲线，这可以解释为不同的发射机制的γ射线和光发射。PKS 0735+178在γ射线波段表现出明显的亮时变硬（HWB）行为，这与观测到的长期和日内时间尺度上的亮时变蓝（BWB）趋势一致。我们发现，HWB和BWB的趋势将在活跃状态，特别是对于历史低状态增强。这一现象表明PKS 0735+178具有一种特殊的活度依赖性颜色行为，可以用喷流发射模型进行很好的解释。
The BL Lac object PKS 0735+178 has shown some complex multiwavelength variation phenomena in previous studies, especially in its color behavior. Bluer-when-brighter, redder-when-brighter, and achromatic behavior were all found to be possible long-term trends of PKS 0735+178. In this work, we collected long-term multiwavelength data on PKS 0735+178, and also performed a multicolor optical monitoring on intraday timescales. Intraday variability was detected on one night. On long timescales, a possible 22 day time lag was found between the R and γ-ray bands. The results of a cross-correlation analysis exhibited strong correlations between various optical bands on both intraday and long timescales. However, only a mild correlation was found between the long-term γ-ray and R-band light curves, which could be interpreted as different emission mechanisms for the γ-ray and optical emissions. PKS 0735+178 showed a significant harder-when-brighter (HWB) behavior in the γ-ray band, which is consistent with the observed optical bluer-when-brighter (BWB) trend on both long-term and intraday timescales. We found that the HWB and BWB trends will be enhanced during active states, especially for the historical low state. Such a phenomenon indicates a special activity-dependent color behavior of PKS 0735+178, and it could be well interpreted by the jet emission model.