Bayesian analysis of radial velocity data of GJ667C with correlated noise: evidence for only two planets
Bayesian analysis of radial velocity data of GJ667C with correlated noise: evidence for only two planets
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具有相关噪声的 GJ667C 径向速度数据的贝叶斯分析：仅存在两颗行星的证据
DOI：
10.1093/mnras/stt2148
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发表时间：
2013
影响因子：
4.8
通讯作者：
M. Hobson
中科院分区：
文献类型：
--
作者：
F. Feroz;M. Hobson
GJ 667 C是一个三重星星系统中质量最小的组成部分，距离地球约6.8 pc（22.1光年）。GJ 667 C最近受到了广泛的关注，因为有人声称它拥有多达七颗行星，其中包括三颗位于宜居带内的超级地球。我们提出了一种贝叶斯技术的径向速度（RV）数据集的相关噪声分量（“红噪声”）的存在下，与未知参数的分析。我们还在模型中引入了超参数，以便在统计上处理测量RV上的低估或高估误差条以及不同数据集之间的不一致。通过将该方法应用于GJ 667 C的RV数据集，我们表明，该数据集包含一个显着的相关（红）噪声分量的HARPS数据的相关时间尺度为9天。我们的分析表明，这些数据仅为两颗行星的存在提供了强有力的证据：GJ 667 Cb和c，周期分别为7.19 d和28.13 d，并暗示存在第三个周期为91 d的信号。这第三个信号的行星性质尚不清楚，需要额外的RV观测来确认。先前声称在这个系统中探测到其他行星是由于错误的白色噪音假设。使用标准的白色噪声假设，我们的方法导致在这个系统中检测到多达五个信号。我们还发现，与红噪声模型，测量不确定度从HARPS为这个系统被低估在~ 50%的水平。
GJ667C is the least massive component of a triple star system which lies at a distance of about 6.8 pc (22.1 light-years) from Earth. GJ667C has received much attention recently due to the claims that it hosts up to seven planets including three super-Earths inside the habitable zone. We present a Bayesian technique for the analysis of radial velocity (RV) data-sets in the presence of correlated noise component ("red noise"), with unknown parameters. We also introduce hyper-parameters in our model in order to deal statistically with under or over-estimated error bars on measured RVs as well as inconsistencies between different data-sets. By applying this method to the RV data-set of GJ667C, we show that this data-set contains a significant correlated (red) noise component with correlation timescale for HARPS data of order 9 days. Our analysis shows that the data only provides strong evidence for the presence of two planets: GJ667Cb and c with periods 7.19d and 28.13d respectively, with some hints towards the presence of a third signal with period 91d. The planetary nature of this third signal is not clear and additional RV observations are required for its confirmation. Previous claims of the detection of additional planets in this system are due the erroneous assumption of white noise. Using the standard white noise assumption, our method leads to the detection of up to five signals in this system. We also find that with the red noise model, the measurement uncertainties from HARPS for this system are under-estimated at the level of ~50 per cent.
影响因子：
7.9
作者：
Anglada-Escude, Guillem;Arriagada, Pamela;Jenkins, James S.
通讯作者：
Jenkins, James S.
影响因子：
6.5
作者：
Anglada-Escude, Guillem;Tuomi, Mikko;Jones, Hugh R. A.
通讯作者：
Jones, Hugh R. A.