arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 2102.05330astro-ph.HEastro-ph.COphysics.space-ph
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天文时间序列的综合功率谱密度分析。II。Swift/BAT长伽马射线暴

A Comprehensive Power Spectral Density Analysis of Astronomical Time Series. II. The Swift/BAT Long Gamma-Ray Bursts

Mariusz Tarnopolski, Volodymyr Marchenko

摘要:

研究了Swift/BAT星表中长伽玛暴的瞬发光变曲线。我们的目标是表征其功率谱密度(PSD),寻找准周期振荡(QPO),并直接在时域进行新的分析。我们使用Lomb-Scargle周期图分析PSD,并使用小波尺度图搜索QPO。我们还尝试使用Hurst指数、$H$和$\mathcal{A}-\mathcal{T}$平面对伽玛暴进行分类。PSD分为三类:指数为$β\in(0,2)$的幂律(PL; $P(f)\propto 1/f^β$)、指数为$β\in(1,3)$的具有不可忽略泊松噪声水平(PLC)的PL以及产生高频指数$β_2\in(2,6)$的平滑破缺PL(SBPL;具有泊松噪声水平)。后者产生1 - 100秒量级的中断时间标度。PL和PLC模型与充分发展的湍流$β=5/3$大体一致。绝大多数伽玛暴(93%)的长时程记忆为$H>0.5$。我们发现在$\mathcal{A}-\mathcal{T}$平面上没有令人信服的亚结构。最后,我们报告了34个新的QPO:具有一个或多个恒定的超前周期,以及几个啁啾信号。断裂和QPO的存在表明存在特征时间尺度,至少在某些GRB中可能与吸积盘中等离子体轨迹的动力学性质有关,为相对论性喷流提供动力。

英文摘要:

We investigated the prompt light curves (LCs) of long gamma-ray bursts (GRBs) from the Swift/BAT catalog. We aimed to characterize their power spectral densities (PSDs), search for quasiperiodic oscillations (QPOs), and conduct novel analyses directly in the time domain. We analyzed the PSDs using Lomb-Scargle periodograms, and searched for QPOs using wavelet scalograms. We also attempted to classify the GRBs using the Hurst exponent, $H$, and the $\mathcal{A}-\mathcal{T}$ plane. The PSDs fall into three categories: power law (PL; $P(f)\propto 1/f^β$) with index $β\in(0,2)$, PL with a non-negligible Poisson noise level (PLC) with $β\in(1,3)$, and a smoothly broken PL (SBPL; with Poisson noise level) yielding high-frequency index $β_2\in(2,6)$. The latter yields break time scales on the order of 1--100\,seconds. The PL and PLC models are broadly consistent with a fully developed turbulence, $β=5/3$. For an overwhelming majority of GRBs (93\%), $H>0.5$, implying ubiquity of the long-term memory. We find no convincing substructure in the $\mathcal{A}-\mathcal{T}$ plane. Finally, we report on 34 new QPOs: with one or more constant leading periods, as well as several chirping signals. The presence of breaks and QPOs suggests the existence of characteristic time scales that in at least some GRBs might be related to the dynamical properties of plasma trajectories in the accretion disks powering the relativistic jets.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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