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首页> 外文期刊>The Astrophysical Journal. Supplement Series >Blazar 3C 454.3 in outburst and quiescence during 2005-2007: Two variable synchrotron emission peaks
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Blazar 3C 454.3 in outburst and quiescence during 2005-2007: Two variable synchrotron emission peaks

机译：2005-2007年间爆发和静止的Blazar 3C 454.3：两个可变的同步加速器发射峰

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We monitored the flaring blazar 3C 454.3 during 2005 June-July with the Spitzer Infrared Spectrograph (IRS: 15epochs), Infrared Array Camera (IRAC: 12 epochs), and Multiband Imaging Photometer (MIPS: 2 epochs). We also made Spitzer IRS, IRAC, and MIPS observations from 2006 December to 2007 January when the source was in a low state, the latter simultaneous with a single Chandra X-ray observation. In addition, we present optical and submillimeter (sub-mm) monitoring data. The 2005-2007 period saw three major outbursts. We present evidence that the radio-optical spectral energy distribution (SED) actually consists of two variable synchrotron peaks, the primary at IR and the secondary at sub-mm wavelengths. The lag between the optical and sub-mm outbursts may indicate that these two peaks arise from two distinct regions along the jet separated by a distance of 0.9-3 pc. The flux at 5-35μm varied by a factor of 40 and the IR peak varied in frequency from 4 × 10~(12)Hz to 4 × 10~(13)Hz between the highest and lowest states in 2005 and 2006, respectively. Variability was well correlated across the mid-IR band, with no measurable lag. Flares that doubled in flux occurred on a timescale of ～5 days, yielding a variability size of <0.05 pc. The IR SED peak moved to higher frequency as a flare brightened, then returned to lower frequency as it decayed. The fractional variability amplitude increased with frequency, which we attribute to decreasing synchrotron self-absorption optical depth. Mid-IR flares may signal the re-energization of a shock that runs into inhomogeneities along the pre-existing jet or in the external medium. The synchrotron peak frequencies during each major outburst may depend upon both the distance from the jet apex and the physical conditions in the shocks. Variation of the Doppler parameter along a curved or helical jet is another possibility. Frequency variability of the IR synchrotron peak may have important consequences for the interpretation of the blazar sequence, and the presence of a secondary peak may give insight into jet structure.
机译：我们在2005年6月至7月期间使用Spitzer红外光谱仪（IRS：15 epoch），红外阵列相机（IRAC：12 epoch）和多波段成像光度计（MIPS：2 epoch）监视了耀斑的blazar 3C 454.3。我们还从2006年12月至2007年1月进行了Spitzer IRS，IRAC和MIPS观测，当时该辐射源处于低态，后者与单个Chandra X射线观测同时进行。此外，我们还提供了光学和亚毫米（sub-mm）监视数据。在2005年至2007年期间，出现了三场重大爆发。我们提供的证据表明，无线电光谱能量分布（SED）实际上由两个可变的同步加速器峰组成，主要在IR，次要在亚毫米波长。光学爆发和亚毫米爆发之间的滞后可能表明，这两个峰值来自沿射流的两个不同区域，它们之间的距离为0.9-3 pc。 5-35μm处的通量变化了40倍，IR峰值的频率分别在2005年和2006年的最高和最低状态之间从4×10〜（12）Hz到4×10〜（13）Hz。可变性在整个中红外波段具有很好的相关性，没有可测量的滞后。通量增加一倍的火炬发生在约5天的时间尺度上，产生的变异大小<0.05 pc。随着耀斑变亮，IR SED峰值移至较高频率，然后随着衰减而返回至较低频率。分数变异幅度随频率增加而增加，这归因于同步加速器自吸收光学深度的减小。中红外耀斑可能预示着冲击的重新激发，沿着先前存在的射流或在外部介质中，冲击会变得不均匀。每个主要爆发期间的同步加速器峰值频率可能取决于与射流顶点的距离以及冲击中的物理条件。多普勒参数沿弯曲或螺旋射流的变化是另一种可能性。红外同步加速器峰的频率可变性可能对blazar序列的解释产生重要影响，并且次峰的存在可能使您更深入地了解射流结构。

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