We forecast the benefits induced by adding the bispectrum anisotropic signal to the standard, two- and three-point, clustering statistics analysis. In particular, we forecast cosmological parameter constraints including the bispectrum higher multipoles terms together with the galaxy power spectrum (monopole plus quadrupole) and isotropic bispectrum (monopole) data vectors. To do so, an analytical covariance matrix model is presented. This template is carefully calibrated on well-known terms of a numerical covariance matrix estimated from a set of simulated galaxy catalogues. After testing the calibration using the power spectrum and isotropic bispectrum measurements from the same set of simulations, we extend the covariance modelling to the galaxy bispectrum higher multipoles. Using this covariance matrix we proceed to perform cosmological parameter inference using a suitably generated mock data vector. Including the bispectrum mutipoles up to the hexadecapole, yields 1-D $68\%$ credible regions for the set of parameters $(b_1,b_2,f,\sigma_8,f_\mathrm{NL},\alpha_\perp, \alpha_\parallel)$ tighter by a factor of 30$\%$ on average for $k_\mathrm{max}=0.09\,h$/Mpc, significantly reducing at the same time the degeneracies present in the posterior distribution.

中文翻译：

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星系红移空间双谱：各向异性的重要性

我们预测了通过将双谱各向异性信号添加到标准的两点和三点聚类统计分析中所带来的好处。特别是，我们预测了宇宙学参数约束，包括双谱更高的多极项以及星系功率谱（单极加四极）和各向同性双谱（单极）数据向量。为此，提出了分析协方差矩阵模型。这个模板是根据从一组模拟星系目录估计的数值协方差矩阵的众所周知的术语仔细校准的。在使用来自同一组模拟的功率谱和各向同性双谱测量测试校准后，我们​​将协方差建模扩展到星系双谱更高的多极点。使用这个协方差矩阵，我们继续使用适当生成的模拟数据向量执行宇宙学参数推断。包括双谱多极子到十六极子，为参数集 $(b_1,b_2,f,\sigma_8,f_\mathrm{NL},\alpha_\perp,\alpha_\ 产生一维 $68\%$ 可信区域对于 $k_\mathrm{max}=0.09\,h$/Mpc，parallel)$ 平均紧缩了 30$\%$，同时显着减少了后验分布中存在的简并性。