Quasi-periodic behaviour in the optical and γ-ray light curves of blazars 3C 66A and B2 1633+38
Quasi-periodic behaviour in the optical and γ-ray light curves of blazars 3C 66A and B2 1633+38
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DOI：
10.1093/mnras/staa134
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发表时间：
2020-01
影响因子：
4.8
通讯作者：
J. Otero-Santos;J. Otero-Santos;J. Acosta-Pulido;J. Acosta-Pulido;J. B. González;J. B. González
中科院分区：
文献类型：
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作者：
J. Otero-Santos;J. Otero-Santos;J. Acosta-Pulido;J. Acosta-Pulido;J. B. González;J. B. González
我们报告的准周期性变化中发现的两个耀变体包括在管家天文台耀变体监测数据样本：BL Lac对象3C 66 A和平谱射电类星体B2 1633+38。我们收集光学光度和偏振数据在V和R波段的这些来源从不同的天文台：圣彼得堡彼得堡大学，克里米亚天体物理观测站，WEBT-GASP，卡塔利纳实时瞬态调查，斯图尔特天文台，STELLA机器人天文台，和Katzman自动成像望远镜。此外，还对费米LAT的γ射线光变曲线进行了分析。三种方法用于搜索数据中的任何周期性行为：Z变换离散相关函数，Lomb-Scargle周期图和加权小波Z变换。我们在两个源的光学光度数据中发现了可能的准周期变化的证据，3C 66 A的周期为1.3年，B2 1633+38的周期为1.9年，显著性在3σ和5σ之间。只有B2 1633+38在2σ-4σ的置信水平下在光学偏振数据集中显示出这种行为的证据。这是第一次报道B2 1633+38的光学光变曲线中的准周期行为的证据。此外，在B2 1633+38的γ射线光变曲线中发现了准周期行为的暗示，置信水平≥2σ，而在该能量范围内没有观察到3C 66 A的周期性。我们提出了不同的喷流排放模型，可以解释准周期性的变化和这两个来源之间的差异。
We report on quasi-periodic variability found in two blazars included in the Steward Observatory Blazar Monitoring data sample: the BL Lac object 3C 66A and the Flat Spectrum Radio Quasar B2 1633+38. We collect optical photometric and polarimetric data in V and R bands of these sources from different observatories: St. Petersburg University, Crimean Astrophysical Observatory, WEBT–GASP, Catalina Real-Time Transient Survey, Steward Observatory, STELLA Robotic Observatory, and Katzman Automatic Imaging Telescope. In addition, an analysis of the γ-ray light curves from Fermi–LAT is included. Three methods are used to search for any periodic behaviour in the data: the Z-transform Discrete Correlation Function, the Lomb–Scargle periodogram and the Weighted Wavelet Z-transform. We find pieces of evidence of possible quasi-periodic variability in the optical photometric data of both sources with periods of ∼3 yr for 3C 66A and ∼1.9 yr for B2 1633+38, with significances between 3σ and 5σ. Only B2 1633+38 shows evidence of this behaviour in the optical polarized data set at a confidence level of 2σ–4σ. This is the first reported evidence of quasi-periodic behaviour in the optical light curve of B2 1633+38. Also, a hint of quasi-periodic behaviour is found in the γ-ray light curve of B2 1633+38 with a confidence level ≥2σ, while no periodicity is observed for 3C 66A in this energy range. We propose different jet emission models that could explain the quasi-periodic variability and the differences found between these two sources.