The unprecedented optical outburst of the quasar 3C 454.3 - The WEBT campaign of 2004–2005
The unprecedented optical outburst of the quasar 3C 454.3 - The WEBT campaign of 2004–2005
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DOI：
10.1051/0004-6361:20064817
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发表时间：
2006-03
影响因子：
6.5
通讯作者：
M. Villata;C. Raiteri;T. Balonek;M. Aller;S. Jorstad;O. Kurtanidze;F. Nicastro;F. Nicastro
中科院分区：
文献类型：
--
作者：
M. Villata;C. Raiteri;T. Balonek;M. Aller;S. Jorstad;O. Kurtanidze;F. Nicastro;F. Nicastro
上下文。射电类星体3C 454.3经历了一次持续一年多的特殊光学爆发，并在2005年春天达到顶峰。探测到的最大亮度为$R=12.0$，这代表了迄今为止观测到的最亮的类星体状态($M_B\sim-31.4$)。目标。为了详细跟踪源的发射行为，全地球布拉扎望远镜(WEBT)组织了一次大型的多波长活动。方法：研究方法。在几个波段进行了连续的光学、近红外和无线电监测。2005年5月，钱德拉和积分卫星的TOO指向以高能量提供了额外的信息。结果。历史上的射电和光学光曲线显示出不同的行为。在大约2001.0年前，光学系统中只存在适度的变化，而在不同的无线电频率上可以看到显著和持久的射电爆发，较高频率的变化先于较低频率的变化。在此日期之后，光学活性增加，射电流量变化较小。这表明，光学和射电辐射来自两个独立的未对准的急流区，内部的光学急流区在2004-2005年爆发期间获得了较小的视角。此外，爆发期间的颜色指数行为(通常更亮时更红)表明存在发光的吸积盘。光学爆发之后发生了一次巨大的毫米暴，在2005年6-7月达到顶峰。高频(37-43 GHz)射电流量从2005年初开始增加，在本观测期结束时(2005年9月底)达到最大值。夏季在43 GHz的VLBA观测证实了射电核心的亮化，并显示出偏振增加。2005年5月探测到一种异常明亮的X射线状态，对应于毫米通量的上升，表明硬X射线光谱具有逆康普顿性质。结论。需要进一步的多频率监测工作，以跟踪这一史无前例的事件的下一个阶段。
Context. The radio quasar 3C 454.3 underwent an exceptional optical outburst lasting more than 1 year and culminating in spring 2005. The maximum brightness detected was $R=12.0$, which represents the most luminous quasar state thus far observed ($M_B \sim -31.4$). Aims. In order to follow the emission behaviour of the source in detail, a large multiwavelength campaign was organized by the Whole Earth Blazar Telescope (WEBT). Methods. Continuous optical, near-IR and radio monitoring was performed in several bands. ToO pointings by the Chandra and INTEGRAL satellites provided additional information at high energies in May 2005. Results. The historical radio and optical light curves show different behaviours. Until about 2001.0 only moderate variability was present in the optical regime, while prominent and long-lasting radio outbursts were visible at the various radio frequencies, with higher-frequency variations preceding the lower-frequency ones. After that date, the optical activity increased and the radio flux is less variable. This suggests that the optical and radio emissions come from two separate and misaligned jet regions, with the inner optical one acquiring a smaller viewing angle during the 2004-2005 outburst. Moreover, the colour-index behaviour (generally redder-when-brighter) during the outburst suggests the presence of a luminous accretion disc. A huge mm outburst followed the optical one, peaking in June-July 2005. The high-frequency (37-43 GHz) radio flux started to increase in early 2005 and reached a maximum at the end of our observing period (end of September 2005). VLBA observations at 43 GHz during the summer confirm the brightening of the radio core and show an increasing polarization. An exceptionally bright X-ray state was detected in May 2005, corresponding to the rising mm flux and suggesting an inverse-Compton nature of the hard X-ray spectrum. Conclusions. A further multifrequency monitoring effort is needed to follow the next phases of this unprecedented event.