Abstract

We present an optical-to-radio study of the BL Lac object S4 0954+658 observations during 1998–2023. The measurements were obtained with the SAO RAS Zeiss-1000 and AS-500/2 0.5-m telescopes in 2003–2023, with the RATAN-600 radio telescope at 1.25 (0.96, 1.1), 2.3, 4.7 (3.7, 3.9), 8.2 (7.7), 11.2, 22.3 (21.7) GHz in 1998–2023, with the IAA RAS RT-32 Zelenchukskaya and Badary telescopes at 5.05 and 8.63 GHz in 2020–2023, and with the RT-22 single-dish telescope of CrAO RAS at 36.8 GHz in 2009–2023. In this period the blazar was showing extremely high broadband activity with the variability amplitude of the flux densities up to 70–100\(\%\) both in the optical and radio domains. During the period of 2014–2023 the blazar displayed extremely high activity in the radio wavelengths, and we detected multiple radio flares of varying amplitude and duration. The large flares last on average from 0.3 to 1 year at 22–36.8 GHz and slightly longer at 5–11.2 GHz. The optical flares are shorter and last 7–50 days. The characteristic time scale \(\tau\) of variation at 5–22 GHz is about 100 days in the most active epoch of 2014–2023 and about 1000 days for the state with lower activity in 2009–2014. We found a general correlation between the optical, radio, and \(\gamma\)-ray flux variations, which suggesting that we observe the same photon population from different emission regions. We estimated the linear size of this region as 0.5–2 pc for different conditions. A broadband radio spectrum with two components of the S4 0954+658 jet was modeled using both electrons and protons as emitting particles. The results suggest that the synchrotron radio waves in this AGN may be produced by relativistic protons.

中文翻译：

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Blazar S4 0954+658 的光学和无线电可变性

摘要

我们对 BL Lac 天体 S4 0954+658 在 1998 年至 2023 年期间的观测结果进行了光学到射电研究。测量结果是在 2003 年至 2023 年期间使用 SAO RAS Zeiss-1000 和 AS-500/2 0.5 米望远镜获得的，其中 RATAN-600 射电望远镜在 1.25 (0.96, 1.1)、2.3、4.7 (3.7, 3.9)、 1998-2023年使用8.2（7.7）、11.2、22.3（21.7）GHz，2020-2023年使用IAA RAS RT-32 Zelenchukskaya和Badary望远镜在5.05和8.63 GHz，以及CrAO的RT-22单口径望远镜2009-2023 年 RAS 频率为 36.8 GHz。在此期间，耀变体表现出极高的宽带活动，在光学和射电域中通量密度的变化幅度高达 70-100 \(\%\) 。在 2014 年至 2023 年期间，耀变体在射电波长中表现出极高的活动性，我们检测到多个不同幅度和持续时间的射电耀斑。大耀斑在 22-36.8 GHz 时平均持续 0.3 至 1 年，在 5-11.2 GHz 时持续时间稍长。光学耀斑较短，持续 7-50 天。5-22 GHz 变化的特征时间尺度\(\tau\)在 2014-2023 年最活跃时期约为 100 天，在 2009-2014 年活动较低的时期约为 1000 天。我们发现光学、射电和伽马射线通量变化之间存在一般相关性 ，这表明我们观察到来自不同发射区域的相同光子群。我们估计不同条件下该区域的线性大小为 0.5-2 pc。使用电子和质子作为发射粒子对具有 S4 0954+658 射流两个分量的宽带无线电频谱进行建模。结果表明，活动星系核中的同步加速器无线电波可能是由相对论性质子产生的。