Fast quasi-periodic oscillations in the eclipsing polar VV Puppis from VLT and XMM-Newton observations
Fast quasi-periodic oscillations in the eclipsing polar VV Puppis from VLT and XMM-Newton observations
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来自 VLT 和 XMM-Newton 观测的食极 VV Puppis 中的快速准周期振荡
DOI：
10.1051/0004-6361/201935741
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发表时间：
2020
影响因子：
6.5
通讯作者：
Bonnet-Bidaud J
中科院分区：
文献类型：
--
作者：
Bonnet-Bidaud J
我们展示了使用安装在 ESO-VLT 望远镜上的 ULTRACAM 相机在三个滤光片（u'、HeIIλ4686、r'）中同时获得的极 VV Puppis 的高时间分辨率光学光度数据。还提供了对从数据库检索的源的长 50 ksXMM-Newton 观察的分析。当吸积极可见时，在源亮相位间隔期间，在光学中可以清楚地检测到准周期振荡（QPO），从而证实了 QPO 与吸积柱基础的关联。在三个滤波器中检测到的 QPO 平均频率为 ∼0.7 Hz，振幅相似为 ∼1%。亮相期间的平均轨道平均功率谱显示出相当广泛的过剩，品质因数 Q=ν/Δν= 5−7，但较小的数据段通常显示出更高的相干性，Q 高达 30。X 射线多镜任务 XMM (0.5–10 keV) 观测首次准确估计了具有高 kT∼40 keV 温度的硬 X 射线分量，并证实了高极紫外 (EUV)-VV Pup 的软/硬比率在 4−15 范围内。详细的 X 射线轨道光变曲线显示，活动极有一段短的 Δψ≃ 0.05 进入自食现象，表明吸积激波高度约为 75 公里。在 0.1–5 Hz 范围内，未检测到振幅上限为 ∼30% 的显着 X 射线 QPO。对震后吸积区域进行详细的流体动力学数值模拟，其参数与 VV Pup 一致，表明辐射不稳定性的预期频率对于 X 射线和光学状态在 ν∼ 40–70 Hz 的值是相同的，比观测值高一个数量级以上。这证实了之前的陈述，即当前的不稳定性模型无法解释极地通常已知的参数内的完整 QPO 特征。
We present high time resolution optical photometric data of the polar VV Puppis obtained simultaneously in three filters (u′, HeIIλ4686,r′) with the ULTRACAM camera mounted at the ESO-VLT telescope. An analysis of a long 50 ksXMM-Newtonobservation of the source, retrieved from the database, is also provided. Quasi-periodic oscillations (QPOs) are clearly detected in the optical during the source bright phase intervals when the accreting pole is visible, confirming the association of the QPOs with the basis of the accretion column. QPOs are detected in the three filters at a mean frequency of ∼0.7 Hz with a similar amplitude ∼1%. Mean orbitally-averaged power spectra during the bright phase show a rather broad excess with a quality factorQ=ν/Δν= 5−7 but smaller data segments commonly show a much higher coherency withQup to 30. The X-ray Multi-mirror Mission XMM (0.5–10 keV) observation provides the first accurate estimation of the hard X-ray component with a highkT∼ 40 keV temperature and confirms the high extreme ultraviolet (EUV)-soft/hard ratio in the range of 4−15 for VV Pup. The detailed X-ray orbital light curve displays a short Δϕ≃ 0.05 ingress into self-eclipse of the active pole, indicative of an accretion shock height of ∼75 km. No significant X-ray QPOs are detected with an amplitude upper limit of ∼30% in the range 0.1–5 Hz. Detailed hydrodynamical numerical simulations of the post-shock accretion region with parameters consistent with VV Pup demonstrate that the expected frequencies from radiative instability are identical for X-rays and optical regime at valuesν∼ 40–70 Hz, more than one order magnitude higher than observed. This confirms previous statements suggesting that present instability models are unable to explain the full QPO characteristics within the parameters commonly known for polars.