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We analyze the non-gaussian density perturbations generated in ekpyrotic/cyclic models based on heterotic M-theory. In this picture, two scalar fields produce nearly scale-invariant entropic perturbations during an ekpyrotic phase that are…

High Energy Physics - Theory · Physics 2014-11-18 Jean-Luc Lehners , Paul J. Steinhardt

We examine an ensemble of 48 simulated clusters to determine the effects of small-scale density fluctuations and large-scale substructure on X-ray measurements of the intracluster medium (ICM) mass. We measure RMS density fluctuations in…

Astrophysics · Physics 2009-10-31 B. Mathiesen , A. E. Evrard , J. J. Mohr

The initial power spectrum of density perturbations, generated during the inflationary epoch, is now constrained by observations on scales $\lambda>5$~Mpc and has a power-law form. The peculiarities of the inflationary process can lead to…

Cosmology and Nongalactic Astrophysics · Physics 2024-09-04 S. V. Pilipenko , S. A. Drozdov , M. V. Tkachev , A. G. Doroshkevich

We explore constraints on inflationary models employing data on large scale structure mainly from COBE temperature anisotropies and IRAS selected galaxy surveys, taking care not to apply linear perturbation theory to data in the non-linear…

Astrophysics · Physics 2009-12-30 R. K. Schaefer , Q. Shafi

Dissipative effects appear in many early-Universe scenarios, yet their universal observational signatures and systematic confrontation with data remain largely unexplored. We employ the Open Effective Field Theory of Inflation (Open EFToI)…

Cosmology and Nongalactic Astrophysics · Physics 2026-03-17 Santiago Agüí Salcedo , Thomas Colas , Petar Suman , Bowei Zhang , James Fergusson , E. P. S. Shellard

I adopt a formalism previously developed by Catelan and Theuns (CT) in order to estimate the impact of primordial non-Gaussianity on the quasi-linear spin growth of cold dark matter protostructures. A variety of bispectrum shapes are…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-12 C. Fedeli

[Abridged] We consider how galaxy clustering data, from Mpc to Gpc scales, from upcoming large scale structure surveys, such as Euclid and DESI, can provide discriminating information about the bispectrum shape arising from a variety of…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-22 Joyce Byun , Rachel Bean

Primordial magnetic fields (PMFs) create a large squeezed-type non-Gaussianity in tensor perturbation, which generates non-Gaussian temperature fluctuations in the cosmic microwave background (CMB). We for the first time derive an…

Cosmology and Nongalactic Astrophysics · Physics 2014-11-13 Maresuke Shiraishi , Toyokazu Sekiguchi

Using a set of $\pppm$ simulation which accurately treats the density evolution of two components of dark matter, we study the evolution of clusters in the Cold + Hot dark matter (CHDM) model. The mass function, the velocity dispersion…

Astrophysics · Physics 2009-10-22 Y. P. Jing , L. Z. Fang

In this paper we provide a consistency relation between the amplitude of the hemispherical bipolar asymmetry, $A$, and the amplitude of the primordial non-Gaussianity in the squeezed limit, $f_{NL}$, as $|A| \lesssim 10^{-1} f_{NL}$. We…

Cosmology and Nongalactic Astrophysics · Physics 2013-10-30 Mohammad Hossein Namjoo , Shant Baghram , Hassan Firouzjahi

We perform Markov chain Monte Carlo analyses to put constraints on the non-flat $\phi$CDM inflation model using Planck 2015 cosmic microwave background (CMB) anisotropy data and baryon acoustic oscillation distance measurements. The…

Cosmology and Nongalactic Astrophysics · Physics 2018-10-24 Junpei Ooba , Bharat Ratra , Naoshi Sugiyama

We point out a possible generation mechanism of non-Gaussian bubbles in the sky due to bubble nucleation in the early universe. We consider a curvaton scenario for inflation and assume that the curvaton field phi, whose energy density is…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-11 Kazuyuki Sugimura , Daisuke Yamauchi , Misao Sasaki

We estimate the value of the matter density parameter \Omega_0 by combining constraints from the galaxy cluster mass function with Croft et al.'s recent measurement of the mass power spectrum, P(k), from \lya forest data. The key assumption…

Astrophysics · Physics 2009-10-31 David H. Weinberg , Rupert A. C. Croft , Lars Hernquist , Neal Katz , Max Pettinini

We revisit the possibility that an excess in the CMB power spectrum at small angular scales (CBI, ACBAR) can be due to galaxy clusters (or compact sources in general). We perform a Gaussian analysis of ACBAR-like simulated data based on…

Astrophysics · Physics 2007-05-23 J. M. Diego , P. Vielva , E. Martinez-Gonalez , J. Silk

We investigated the structures on scales beyond the typical clusters of galaxies. These structures are crucial to understand the cosmic gravitational clustering in the pre-virialized stage, or quasilinear r\`egime. Based on the…

Astrophysics · Physics 2009-10-31 Wen Xu , Li-Zhi Fang , Zugan Deng

I present a general discussion of the evolution and model-dependence of both the linear and nonlinear power spectrum of density fluctuations. The features of the linear power spectrum in cosmological models with cold dark matter (CDM) and…

Astrophysics · Physics 2009-10-31 Chung-Pei Ma

We discuss non-Gaussianity and baryonic isocurvature fluctuations in the curvaton scenario, assuming that the baryon asymmetry of the universe originates only from the decay products of the inflaton. When large non-Gaussianity is realized…

High Energy Physics - Phenomenology · Physics 2009-02-02 Takeo Moroi , Tomo Takahashi

We investigate the potential of cosmological observations, such as galaxy surveys, for constraining degenerate higher-order scalar-tensor (DHOST) theories, focusing in particular on the linear growth of the matter density fluctuations. We…

Cosmology and Nongalactic Astrophysics · Physics 2019-05-29 Shin'ichi Hirano , Tsutomu Kobayashi , Daisuke Yamauchi , Shuichiro Yokoyama

We discuss how primordial non-Gaussianity of the curvature perturbation helps to constrain models of the early universe. Observations are consistent with Gaussian initial conditions, compatible with the predictions of the simplest models of…

Cosmology and Nongalactic Astrophysics · Physics 2014-11-26 Christian T. Byrnes

We revisit the cloud-in-cloud problem for non-Gaussian density fluctuations. We show that the extended Press-Schechter (EPS) formalism for non-Gaussian fluctuations has a flaw in describing mass functions regardless of type of filtering. As…

Astrophysics · Physics 2009-11-07 Kaiki Taro Inoue , Masahiro Nagashima