Primordial non-Gaussianity, statistics of collapsed objects, and the integrated Sachs-Wolfe effect

By N. Afshordi, A. Tolley. 2008

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Any hint of non-Gaussianity in the cosmological initial conditions will provide us with a unique window into the physics of the early Universe. We show that the impact of a small local primordial non-Gaussianity (generated on superhorizon scales) on the statistics of collapsed objects (such as galaxies or clusters) can be approximated by using slightly modified, but Gaussian, initial conditions, which we describe through simple analytic expressions. Given that numerical simulations with Gaussian initial conditions are relatively well studied, this equivalence provides us with a simple tool to predict signatures of primordial non-Gaussianity in the statistics of collapsed objects. In particular, we describe the predictions for non-Gaussian mass function, and also confirm the recent discovery of a nonlocal bias on large scales [N. Dalal, O. Dore, D. Huterer, and A. Shirokov, Phys. Rev. D 77, 123514 (2008).][S. Matarrese and L. Verde, Astrophys. J. 677, L77 (2008).], as a signature of primordial non-Gaussianity. We then study the potential of galaxy surveys to constrain non-Gaussianity using their autocorrelation and cross correlation with the cosmic microwave background (CMB) (due to the integrated Sachs-Wolfe effect), as a function of survey characteristics, and predict that they will eventually yield an accuracy of $\ensuremath{\Delta}{f}_{NL}\ensuremath{\sim}0.1$ and 3, respectively, which will be better than or competitive with (but independent of) the best predicted constraints from the CMB. Interestingly, the cross correlation of the CMB and the NRAO VLA Sky Survey galaxy survey already shows a hint of a large local primordial non-Gaussianity: ${f}_{NL}=236\ifmmode\pm\else\textpm\fi{}127$.

Subfields: Applied Mathematics, Astronomy and Astrophysics

View Paper: https://www.semanticscholar.org/paper/6690e6f37ec63a04b0e11de452d13fee061f85f7

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Citations in the corpus

Halo mass function and scale-dependent bias from N-body simulations with non-Gaussian initial conditions (2008, methodology): “Similar calculations have been presented by Matarrese & Verde (2008), Slosar et al. (2008), Afshordi & Tolley (2008) and McDonald (2008).”
Scale-dependent bias induced by local non-Gaussianity: a comparison to N-body simulations (2008, background): “Further work has confirmed the basic picture (Afshordi & Tolley 2008; McDonald 2008; Taruya et al. 2008).”
Probing primordial non-Gaussianity with SKA galaxy redshift surveys: a fully relativistic analysis (2014, methodology): “(4) we have used the large-scale structure (LSS) convention for defining fNL, as opposed to the CMB convention (Afshordi & Tolley 2008; Pillepich et al. 2010; Carbone et al. 2008; Grossi et al. 2009).”
Primordial non-Gaussianity from the large-scale structure (2010, background): “The non-Gaussian halo bias also leaves a signature in cross-correlation statistics of weak cosmic shear (galaxy–galaxy and galaxy–CMB) [202, 203] and in the integrated Sachs–Wolfe (ISW) effect [148, 149].”
Radio and millimeter continuum surveys and their astrophysical implications (2009, background): “Hence we suggest that the amplitude of the ISW cross-correlation does not support the case for new gravitational physics on cosmological scales (Afshordi et al. 2008) or for a large local primordial non-Gaussianity (Afshordi & Tolley 2008).”
Formation of Galaxy Clusters (2012, result): “As was discovered by Dalal et al. (2008) and confirmed in subsequent analytical (Afshordi & Tolley 2008; Matarrese & Verde 2008; McDonald 2008; Slosaret al. 2008; Taruya, Koyama & Matsubara 2008) and numerical studies (Desjacques, S ljak & Iliev 2009; Grossi et al. 2009; Pillepich, Porciani & Hahn…”
Constraining primordial non-Gaussianity with future galaxy surveys (2011, background): “…the underlying mass-density field is altered, becoming strongly scaledependent in the local and orthogonal cases (Dalal et al. 2008; Matarrese & Verde 2008; Slosar et al. 2008; Afshordi & Tolley 2008; Valageas 2010; Giannantonio & Porciani 2010; Schmidt & Kamionkowski 2010; Desjacques et al. 2011).”
Large-scale bias and efficient generation of initial conditions for nonlocal primordial non-Gaussianity (2011, background): “(114) and similarly for the Gaussian case [9, 24, 66–68].”
Primordial Non-Gaussianity and Bispectrum Measurements in the Cosmic Microwave Background and Large-Scale Structure (2010, background): “See section 2.1 in Sefusatti et al. (2007) for an brief overview of previous work andAfshordi & Tolley (2008); Dalal et al. (2008); Desjacques et al. (2009); Fedeli et al. (2009); Grossi et al. (2009); Lam & Sheth (2009); Lo Verde et al. (2008); Maggiore & Riotto (2009); Oguri (2009); Pillepich et a”
Large-scale non-Gaussian mass function and halo bias: tests on N-body simulations (2009, background): “As noted by, for example, LoVerde et al. (2008), Afshordi & Tolley (2008) and Pillepich et al. (2008), different authors use different conventions.”
PRIMORDIAL NON-GAUSSIANITY, SCALE-DEPENDENT BIAS, AND THE BISPECTRUM OF GALAXIES (2009, background): “(1), may require modifications, in light of recent analytical (Dalal et al. 2008; Matarrese & Verde 2008; Slosar et al. 2008; Afshordi & Tolley 2008; Taruya et al. 2008; McDonald 2008) and numerical (Dalal et al. 2008; Desjacques et al. 2008; Pillepich et al. 2008; Grossi et al. 2009) studies of…”