对伽马射线 blazars 中年尺度稳定调制的形态学搜索

中文摘要 AI 辅助

blazar 的伽马射线光变曲线中存在年尺度准周期振荡（QPOs），被认为是超大质量双黑洞和进动喷流的信号，但红噪声可模拟周期性，仅检测无法证实其持续性或周期稳定性。我们开发并校准了一种形态学框架，用于表征年尺度调制并约束 blazars 中稳定调制的发生率。我们分析了 120 条跨度 18.1 年的 Fermi-LAT 光变曲线，采用奇异谱分析选择振荡模式和周期，同时用加权小波 Z 变换脊跟踪测量持续性、周期漂移和循环间波动性。通过流量随机化、10000 次红噪声模拟和约 20000 次注入对分类进行校准。在 97 个质量筛选后的源中，2 个显示出与平稳周期一致的持续相干调制（Rank I：PG 1553+113 和 B2 1215+30），6 个显示出无法证实平稳性的相干调制（Rank II），89 个属于 Rank III。Rank I 和 Rank II 均未显著超过红噪声预期。在信噪比（SNR）=1 时，平稳的 1-3 年注入在不同周期下有 63%-97% 的试验达到 Rank I，SNR=2 时达 100%；92% 的漂移注入达到 Rank II。这些结果将稳定的近似正弦 1-3 年调制限制在样本中至多 7%（SNR≥1）和 5%（SNR≥2，95%置信度）。PG 1553+113 的虚警概率最低，为试验后 4.7%。稳定的年尺度调制并不常见，且没有源被证实为周期性。该框架可区分持续平稳调制与周期可能演化或波动的相干变异性，但无法区分物理机制。PG 1553+113 和 B2 1215+30 是监测和连续引力波搜索的候选体，尽管它们的稳定性不能证实双黑洞起源。

英文摘要

Year-scale quasi-periodic oscillations (QPOs) in blazar gamma-ray light curves have been proposed as signatures of supermassive binary black holes and precessing jets. Red noise can mimic periodicity, and detection alone does not establish persistence or period stability. We develop and calibrate a morphological framework to characterize year-scale modulation and constrain the incidence of stable modulation in blazars. We analyze 120 Fermi-LAT light curves spanning 18.1 yr. Singular spectrum analysis selects the oscillatory mode and period, while weighted wavelet Z-transform ridge tracking measures persistence, period drift, and cycle-to-cycle volatility. Flux randomization, 10,000 red-noise simulations, and about 20,000 injections calibrate the classification. Of 97 quality-selected sources, two show persistent, coherent modulation consistent with a stationary period (Rank I: PG 1553+113 and B2 1215+30), six show coherent modulation whose stationarity cannot be established (Rank II), and 89 form Rank III. Neither Rank I nor Rank II significantly exceeds red-noise expectations. Stationary 1-3 yr injections reach Rank I in 63-97% of trials at signal-to-noise ratio (SNR) = 1, depending on period, and 100% at SNR = 2; 92% of drifting injections reach Rank II. These results limit stable, approximately sinusoidal 1-3 yr modulation to at most 7% of the sample at SNR >= 1 and 5% at SNR >= 2 (95% confidence). PG 1553+113 has the lowest false-alarm probability, 4.7% after trials. Stable year-scale modulation is uncommon, and no source is established as periodic. The framework distinguishes persistent, stationary modulation from coherent variability whose period may evolve or fluctuate, but not the physical mechanism. PG 1553+113 and B2 1215+30 are candidates for monitoring and continuous gravitational-wave searches, although their stability does not establish a binary origin.

发表机构

• Universidad Complutense de Madrid（马德里康普顿斯大学）
• Clemson University（克莱姆森大学）
• Julius-Maximilians-Universität Würzburg（维尔茨堡朱利叶斯-马克西米利安大学）
• Deutsches Elektronen-Synchrotron DESY（德国电子同步辐射中心）

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