PRIMORDIAL NON-GAUSSIANITY, SCALE-DEPENDENT BIAS, AND THE BISPECTRUM OF GALAXIES
By D. Jeong, E. Komatsu. 2009
141 citations recorded by the source corpus.
The three-point correlation function of cosmological fluctuations is a sensitive probe of the physics of inflation. We calculate the bispectrum, Bg(k1, k2, k3), Fourier transform of the three-point function of density peaks (e.g., galaxies), using two different methods: the Matarrese–Lucchin–Bonometto formula and the locality of galaxy bias. The bispectrum of peaks is not only sensitive to that of the underlying matter density fluctuations, but also to the four-point function. For a physically motivated, local form of primordial non-Gaussianity in the curvature perturbation, Φ = ϕ + fNLϕ2 + gNLϕ3, where ϕ is a Gaussian field, we show that the galaxy bispectrum contains five physically distinct pieces: (1) non-linear gravitational evolution, (2) non-linear galaxy bias, (3) fNL, (4) f2NL, and (5) gNL. While (1), (2), and a part of (3) have been derived in the literature, (4) and (5) are derived in this paper for the first time. We also find that, in the high-density peak limit, (3) receives an enhancement of a factor of ∼15 relative to the previous calculation for the squeezed triangles (k1 ≈ k2 ≫ k3). Our finding suggests that the galaxy bispectrum is more sensitive to fNL than previously recognized, and is also sensitive to a new term, gNL. For a more general form of local-type non-Gaussianity, the coefficient f2NL can be interpreted as τNL, which allows us to test multi-field inflation models using the relation between the three- and four-point functions. The usual terms from Gaussian initial conditions, (1) and (2), have the smallest signals in the squeezed configurations, while the others have the largest signals; thus, we can distinguish them easily. We cannot interpret the effects of fNL on Bg(k1, k2, k3) as a scale-dependent bias, and thus replacing the linear bias in the galaxy bispectrum with the scale-dependent bias known for the power spectrum results in an incorrect prediction. As the importance of primordial non-Gaussianity relative to the non-linear gravity evolution and galaxy bias increases toward higher redshifts, galaxy surveys probing a high-redshift universe are particularly useful for probing the primordial non-Gaussianity.
Subfields: Astronomy and Astrophysics, Instrumentation
View Paper: https://www.semanticscholar.org/paper/167166d6b69b2aec6dec72e2773356db4147d9da
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In Astronomy and Astrophysics
- E. Sefusatti
- Uros Seljak
- V. Desjacques
- M. Liguori
- J. Fergusson
- E. Shellard
- R. Scoccimarro
- Marc Manera
In Instrumentation
- E. Sefusatti
- R. Scoccimarro
- M. Liguori
- E. Shellard
- J. Fergusson
- Marc Manera
- M. Ishak
- Kwan Chuen Chan
Citations in the corpus
- Primordial non-Gaussianity from the large-scale structure (2010, background): “As recognized by [64, 170], equation (37) misses an important term that may significantly enhance the sensitivity of the galaxy bispectrum to non-Gaussian initial conditions.”
- The Intrinsic Alignment of Galaxies and its Impact on Weak Gravitational Lensing in an Era of Precision Cosmology (2014, background): “The bispectrum has been shown to break degeneracies in the cosmological parameters and to probe additional physics like the non-Gaussianity of large-scale structure (Bernardeau et al., 1997; van Waerbeke et al., 1999; Matarrese et al., 2000; Van Waerbeke et al., 2001; Verde et al., 2001; Takada and ”
- Large-scale bias and efficient generation of initial conditions for nonlocal primordial non-Gaussianity (2011, background): “[26] D.”
- Review of local non-Gaussianity from multi-field inflation (2010, unknown): “may become even tighter [131–135].”
- Constraining primordial non-Gaussianity with future galaxy surveys (2011, unknown): “Moreover, in full analogy with the CMB case, any 3-point statistic of the galaxy distribution is affected by PNG (Sefusatti & Komatsu 2007; Jeong & Komatsu 2009).”
- Primordial Non-Gaussianity and Bispectrum Measurements in the Cosmic Microwave Background and Large-Scale Structure (2010, methodology): “Since current bispectrum analysis of WMAP data (Komatsu et al., 2009; Smith et al., 2009) find f loc.”