Photopolarimetric Monitoring of Blazars in the Optical and Near-Infrared Bands with the Kanata Telescope. I. Correlations between Flux, Color, and Polarization
Photopolarimetric Monitoring of Blazars in the Optical and Near-Infrared Bands with the Kanata Telescope. I. Correlations between Flux, Color, and Polarization
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DOI：
10.1093/pasj/63.3.327
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发表时间：
2011-05
影响因子：
2.3
通讯作者：
Y. Ikejiri;M. Uemura;M. Sasada;R. Ito;M. Yamanaka;K. Sakimoto;A. Arai;Y. Fukazawa;T. Ohsugi;K. Kawabata;Michitoshi Yoshida;S. Sato;M. Kino
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文献类型：
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作者：
Y. Ikejiri;M. Uemura;M. Sasada;R. Ito;M. Yamanaka;K. Sakimoto;A. Arai;Y. Fukazawa;T. Ohsugi;K. Kawabata;Michitoshi Yoshida;S. Sato;M. Kino
我们报道了blazar中通量、颜色和偏振变化在日-月时间尺度上的相关性，并讨论了它们的普遍方面。从2008年到2010年，我们使用连接在“Kanata”1.5米望远镜上的TRISPEC对光学和近红外波段的42颗blazar进行了监测。我们发现，28个blazar在其全部或部分时间序列数据集中显示出“更亮时更蓝”的趋势。这相当于观察了>；10天的对象的88%。因此，我们的观测毫不含糊地证实了“亮时蓝”的趋势在blazar喷流的排放中很常见。这一趋势显然是由变异成分产生的，变异成分具有恒定的相对蓝色和潜在的红色成分。突出的短期耀斑在天-周的时间尺度上往往表现出光谱滞后；它们的上升相位比耀斑最大值附近的衰减相位更蓝。与较强的通量-颜色相关性相比，通量与偏振度的相关性相对较弱，只有10个对象显示出显著的正相关。只在三个物体中检测到偏振旋转：PKS1510-089、3C 454.3和PKS1749+096，可能在S50716+714中。我们还研究了变化度与光度和同步加速器峰值频率的关系。结果发现，亮度较低和u_峰值较高的天体在通量、颜色和偏振度方面的幅度变化都较小。我们的观察表明，存在几个不同的发射源，它们具有不同的时间尺度、颜色和偏振变化。我们认为，相对论壳层内激波的能量注入是导致blazar在日和月的时间尺度上变化的主要因素。
We report on the correlation between the flux, color and polarization variations on time scales of days--months in blazars, and discuss their universal aspects. We performed monitoring of 42 blazars in the optical and near-infrared bands from 2008 to 2010 using TRISPEC attached to the "Kanata" 1.5-m telescope. We found that 28 blazars exhibited "bluer-when-brighter" trends in their whole or a part of time-series data sets. This corresponds to 88% of objects that were observed for >10 days. Thus, our observation unambiguously confirmed that the "bluer-when-brighter" trend is common in the emission from blazar jets. This trend was apparently generated by a variation component with a constant and relatively blue color and an underlying red component. Prominent short-term flares on time scales of days--weeks tended to exhibit a spectral hysteresis; their rising phases were bluer than their decay phases around the flare maxima. In contrast to the strong flux--color correlation, the correlation of the flux and polarization degree was relatively weak; only 10 objects showed significant positive correlations. Rotations of polarization were detected only in three objects: PKS 1510-089, 3C 454.3, and PKS 1749+096, and possibly in S5 0716+714. We also investigated the dependence of the degree of variability on the luminosity and the synchrotron peak frequency, \nu_peak. As a result, we found that lower luminosity and higher \nu_peak objects had smaller variations in their amplitudes both in the flux, color, and polarization degree. Our observation suggests the presence of several distinct emitting sources, which have different variation time-scales, colors, and polarizations. We propose that the energy injection by, for example, internal shocks in relativistic shells is a major factor for blazar variations on time scales of both days and months.