A Consolidated Framework of the Color Variability in Blazars: Long-term Optical/Near-infrared Observations of 3C 279
A Consolidated Framework of the Color Variability in Blazars: Long-term Optical/Near-infrared Observations of 3C 279
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DOI：
10.3847/1538-4357/aa79fc
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发表时间：
2017-06
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影响因子：
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通讯作者：
J. Isler;C. Urry;P. Coppi;C. Bailyn;M. Brady;E. MacPherson;M. Buxton;Ikramul Hasan
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文献类型：
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作者：
J. Isler;C. Urry;P. Coppi;C. Bailyn;M. Brady;E. MacPherson;M. Buxton;Ikramul Hasan
我们利用智利塞罗托洛市的中小口径研究望远镜系统和费米伽马射线空间望远镜获得的γ射线通量，评估了3C279在7年时间尺度上在γ-射线耀斑和非耀斑状态下的光学/近红外(OIR)颜色变化。这一观测战略与以前的blazar颜色可变性研究有两个关键方面的不同：(1)报告的颜色可变性是通过近红外波长通过光学系统评估的，(2)颜色可变性是在比单个耀斑或地面观测季节长得多的时间尺度上评估的。我们强调3C279是因为它复杂的颜色可变性，这很难与平谱射电类星体颜色可变性相关的简单的“更亮时更红”的行为相一致。我们认为，观测到的OIR颜色变化取决于喷流和圆盘发射的组合。我们用一个变量来描述这一行为，它代表了从圆盘为主的系统到混合贡献的系统再到喷流主导的系统的平稳过渡，这解释了同一blazar中OIR颜色随时间的长期变化。这提出了一个通用的方案，可以适用于其他运动装饰品的OIR颜色变化。
We evaluate the optical/near-infrared (OIR) color variability of 3C 279 in both γ-ray flaring and non-flaring states over 7-year timescales using the Small and Medium Aperture Research Telescope System in Cerro Tololo, Chile and γ-ray fluxes obtained from the Fermi Gamma-ray Space Telescope. This observing strategy differs from previous blazar color variability studies in two key ways: (1) the reported color variability is assessed across optical through near-infrared wavelengths, and (2) the color variability is assessed over timescales significantly longer than an individual flare or ground-based observing season. We highlight 3C 279 because of its complex color variability, which is difficult to reconcile with the simple “redder-when-brighter” behavior often associated with Flat Spectrum Radio Quasar color variability. We suggest that the observed OIR color changes depend on a combination of the jet and disk emission. We parameterize this behavior in terms of a single variable, , representing a smooth transition from a disk-dominated system, to a mixed contribution, to a jet-dominated system, which provides an explanation of the long-term OIR color variability in the same blazar over time. This suggests a general scheme that could apply to OIR color variability in other blazars.