Long and short term variability of seven blazars in six near-infrared/optical bands
Long and short term variability of seven blazars in six near-infrared/optical bands
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DOI：
10.1051/0004-6361/201321558
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发表时间：
2013-08
影响因子：
6.5
通讯作者：
A. Sandrinelli;S. Covino;A. Treves
中科院分区：
文献类型：
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作者：
A. Sandrinelli;S. Covino;A. Treves
语境。我们展示了六个 BL Lac 天体 PKS 0537-441、PKS 0735+17、OJ 287、PKS 2005-489、PKS 2155-304 和 W Comae 的光变曲线，以及平光谱射电类星体 PKS 1510-089 的光变曲线，作为 2017 年开始的近红外/光波段光度监测计划的一部分。 2004。所有来源都是费米耀变体。目标。我们的目的是研究短期和长期尺度上的通量和光谱变化。独立于源活动的系统监控可保证大样本量统计，并允许在整个时间范围内的每周或每日时间尺度以及某些时期的夜间时间尺度上对不同活动状态进行公正的查看。方法。数据是通过位于拉西拉（智利）的 ESO 基地的 REM 望远镜获得的。光变曲线是从 2005 年 4 月到 2012 年 6 月在光学/近红外 VRIJHK 波段收集的。结果。在 PKS 0537-441、PKS 1510-089 和 PKS 2155-304 中观察到了 3 mag 的变化，这是近红外范围内跨越的最大范围。颜色强度图显示出相当不同的形态。一般来说，光谱能量分布很好地符合幂律，但一些偏差在低态下更为明显。 PKS 0537-441 和 PKS 2155-304 详细记录了夜间间隔期间的一些变异事件。对于后一个源，可变性时间尺度意味着较大的相对论射束因子。
Context. We present the light curves of six BL Lac objects, PKS 0537-441, PKS 0735+17, OJ 287, PKS 2005-489, PKS 2155-304, and W Comae, and of the flat spectrum radio quasar PKS 1510-089, as a part of a photometric monitoring program in the nearinfrared/optical bands started in 2004. All sources are Fermi blazars. Aims. Our purpose is to investigate flux and spectral variability on short and long time scales. Systematic monitoring, independent of the activity of the source, guarantees large sample size statistics, and allows an unbiased view of different activity states on weekly or daily time scales for the whole timeframe and on nightly time scales for some epochs. Methods. Data were obtained with the REM telescope located at the ESO premises of La Silla (Chile). Light curves were gathered in the optical/near-infrared VRIJHK bands from April 2005 to June 2012. Results. Variability 3 mag is observed in PKS 0537-441, PKS 1510-089 and PKS 2155-304, the largest ranges spanned in the near-infrared. The color intensity plots show rather different morphologies. The spectral energy distributions in general are well fitted by a power law, with some deviations that are more apparent in low states. Some variability episodes during a night interval are well documented for PKS 0537-441 and PKS 2155-304. For the latter source the variability time scale implies a large relativistic beaming factor.