Common-red-signal analysis with 24-yr high-precision timing of the European Pulsar Timing Array: Inferences in the stochastic gravitational-wave background search
Common-red-signal analysis with 24-yr high-precision timing of the European Pulsar Timing Array: Inferences in the stochastic gravitational-wave background search
复制标题
欧洲脉冲星授时阵列 24 年高精度授时的共红信号分析：随机引力波背景搜索的推论
DOI：
10.1093/mnras/stab2833
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发表时间：
2021
期刊：
影响因子：
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通讯作者：
H. Xu
中科院分区：
文献类型：
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作者：
S. Chen;R. N. Caballero;Y. J. Guo;A. Chalumeau;K.Liu;G. Shaifullah;K. Lee;S. Babak;G. Desvignes;A. Parthasarathy;H. Hu;E. V. D. Wateren;J. Antoniadis;A. B. Nielsen;C. Bassa;A. Berthereau;M. Burgay;D. Champion;I. Cognard;M. Falxa;R. Ferdman;P. Freire;J. Gair;E. Graikou;L. Guillemot;J. Jang;G. Janssen;R. Karuppusamy;M. Keith;M. Kramer;X. Liu;A. Lyne;R. Main;J. McKee;M. Mickaliger;B. Perera;D. Perrodin;A. Petiteau;N. Porayko;A. Possenti;A. Samajdar;S. Sanidas;A. Sesana;L. Speri;B. Stappers;G. Theureau;C. Tiburzi;A. Vecchio;J. Verbiest;J. Wang;L. Wang;H. Xu
本文介绍了利用欧洲脉冲星定时阵列（EPTA）数据发布2 （DR2）中的6颗射电毫秒脉冲星对广义相对论预测的随机引力波背景（GWB）的搜索结果，这些数据覆盖了长达24年的时间跨度。GWB表现为所有脉冲星共有的长期低频随机信号，一种具有赫灵-唐斯空间相关特征的共同红色信号（CRS）。我们的分析是用两个独立的管道进行的，\eprise{}和\tn{}+\ftwo{}，它们产生一致的结果。搜索同时估计其空间相关性的CRS会产生与GWB理论预测相容的光谱特性，但不会产生GWB检测所需的高清相关性测量。进一步对不同类型的CRSs（包括GWB）进行贝叶斯模型比较，发现最受欢迎的模型是由幂定律描述的常见不相关红噪声，其中$ a = 5.13_{-2.73}^{+4.20} \乘以10^{-15}$和$\gamma = 3.78_{-0.59}}^{+0.69}$（95%可信区域）。通过圆形的超大质量黑洞双星将GWB的光谱指数固定为$\gamma=13/3$，其振幅为$A =2.95_{-0.72}^{+0.89} \乘以10^{-15}$。我们实施了三种不同的模型，BAYESEPHEM， LINIMOSS和EPHEMGP，以解决可能的太阳系星历（SSE）系统问题，并得出结论，我们的结果可能只略微依赖于这些影响。这项工作建立在EPTA DR1研究的方法和模型的基础上。我们证明了在相同的分析框架下，数据集扩展后的结果是一致的。
We present results from the search for a stochastic gravitational-wave background (GWB) as predicted by the theory of General Relativity using six radio millisecond pulsars from the Data Release 2 (DR2) of the European Pulsar Timing Array (EPTA) covering a timespan up to 24 years. A GWB manifests itself as a long-term low-frequency stochastic signal common to all pulsars, a common red signal (CRS), with the characteristic Hellings-Downs (HD) spatial correlation. Our analysis is performed with two independent pipelines, \eprise{} and \tn{}+\ftwo{}, which produce consistent results. A search for a CRS with simultaneous estimation of its spatial correlations yields spectral properties compatible with theoretical GWB predictions, but does not result in the required measurement of the HD correlation, as required for GWB detection. Further Bayesian model comparison between different types of CRSs, including a GWB, finds the most favoured model to be the common uncorrelated red noise described by a power-law with $A = 5.13_{-2.73}^{+4.20} \times 10^{-15}$ and $\gamma = 3.78_{-0.59}^{+0.69}$ (95\% credible regions). Fixing the spectral index to $\gamma=13/3$ as expected from the GWB by circular, inspiralling supermassive black-hole binaries results in an amplitude of $A =2.95_{-0.72}^{+0.89} \times 10^{-15}$. We implement three different models, BAYESEPHEM, LINIMOSS and EPHEMGP, to address possible Solar-system ephemeris (SSE) systematics and conclude that our results may only marginally depend on these effects. This work builds on the methods and models from the studies on the EPTA DR1. We show that under the same analysis framework the results remain consistent after the data set extension.