Fluctuations with wavelengths larger than the volume of a galaxy survey affect the measurement of the galaxy power spectrum within the survey itself. In the presence of local Primordial Non- Gaussianities (PNG), in addition to the super-sample matter density and tidal fluctuations, the large-scale gravitational potential also induces a modulation of the observed power spectrum. In this work we investigate this modulation by computing for the first time the response of the redshift-space galaxy power spectrum to the presence of a long wavelength gravitational potential, fully accounting for the stochastic contributions. For biased tracers new response functions arise due to couplings between the small-scale fluctuations in the density, velocity and gravitational fields, the latter through scale dependent bias operators, and the large-scale gravitational potential. We study the impact of the super-sample modes on the measurement of the amplitude of the primordial bispectrum of the local-shape, $f_{\rm NL}^{\rm loc}$, accounting for modulations of both the signal and the covariance of the galaxy power spectrum by the long modes. Considering DESI-like survey specifications, we show that in most cases super-sample modes cause little or no degradation of the constraints, and could actually reduce the errorbars on $f_{\rm NL}^{\rm loc}$ by (10 - 30)\%, if external information on the bias parameters is available.

中文翻译：

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局部原始非高斯性和超样本方差

波长大于星系调查体积的波动会影响调查本身内星系功率谱的测量。在存在局部原始非高斯性 (PNG) 的情况下，除了超样本物质密度和潮汐波动之外，大尺度引力势还会引起观测到的功率谱的调制。在这项工作中，我们通过首次计算红移空间星系功率谱对长波长引力势存在的响应来研究这种调制，充分说明随机贡献。对于偏置示踪剂，由于密度、速度和重力场的小尺度波动之间的耦合，产生了新的响应函数，后者通过尺度相关的偏置算子，和大规模的引力势。我们研究了超采样模式对局部形状原始双谱幅度测量的影响，$f_{\rm NL}^{\rm loc}$，考虑了信号和长模式对星系功率谱的协方差。考虑到类似 DESI 的调查规范，我们表明在大多数情况下，超样本模式几乎不会或不会导致约束退化，并且实际上可以将 $f_{\rm NL}^{\rm loc}$ 上的误差条减少 (10 - 30)\%，如果有关偏置参数的外部信息可用。考虑到长模式对星系功率谱的信号和协方差的调制。考虑到类似 DESI 的调查规范，我们表明在大多数情况下，超样本模式几乎不会或不会导致约束退化，并且实际上可以将 $f_{\rm NL}^{\rm loc}$ 上的误差条减少 (10 - 30)\%，如果有关偏置参数的外部信息可用。考虑到长模式对星系功率谱的信号和协方差的调制。考虑到类似 DESI 的调查规范，我们表明在大多数情况下，超样本模式几乎不会或不会导致约束退化，并且实际上可以将 $f_{\rm NL}^{\rm loc}$ 上的误差条减少 (10 - 30)\%，如果有关偏置参数的外部信息可用。