The high-mass X-ray binary LS I +61°303 is detected across the electromagnetic spectrum from radio until the very high energy $\gamma$-ray regime. The emission is not only highly variable on many time scales, but is also periodic at all observed wavelengths. Periodic modulation was observed on different time-scales, ranging from hours, over months to several years. The subject of this article is a super-orbital, long-term modulation of ∼4.6 years. We review the observation of this periodic modulation at multiple wavelengths and investigate systematic relationships between them. IN particular, radio observations reveal that the long-term modulation is a very stable feature of the source. Observations at other wavelengths result in a phase-shift of the modulationpattern that is a systematic function of energy. The stability of this period favors a scenario in which the long-term modulation is the result of a precessing jet giving rise to periodic changes in the Doppler factor, beating with the orbital modulation of the accretion rate. We explain the phase-shifts across energy bands in a scenario with shorter wavelengths originating closer to the base of the presessing jet. A significant deviation of the TeV emission from this trend possibly requires a different explanation related to magnetic reconnection events.

中文翻译：

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LS I +61°303 多波长长期调制的进动射流场景

高质量 X 射线双星 LS I +61°303 在从无线电到非常高能量的电磁波谱中被检测到 $\gamma$-射线制度。发射不仅在许多时间尺度上变化很大，而且在所有观察到的波长上也是周期性的。在不同的时间尺度上观察到周期性调制，范围从数小时、数月到数年不等。本文的主题是约 4.6 年的超轨道长期调制。我们回顾了在多个波长下对这种周期性调制的观察，并研究了它们之间的系统关系。特别是，无线电观测表明，长期调制是源的一个非常稳定的特征。对其他波长的观察导致调制模式的相移，这是能量的系统函数。该周期的稳定性有利于长期调制是进动射流引起多普勒因子周期性变化的结果，随着吸积率的轨道调制而跳动。我们解释了在较短波长起源于更接近压射流底部的情况下跨能带的相移。TeV 发射与这种趋势的显着偏差可能需要与磁重联事件相关的不同解释。