First Structure Formation. II. Cosmic String plus Hot Dark Matter Models

1998 ◽  
Vol 508 (2) ◽  
pp. 530-534 ◽  
Author(s):  
Tom Abel ◽  
Albert Stebbins ◽  
Peter Anninos ◽  
Michael L. Norman
Keyword(s):  
Dark Matter ◽  
Structure Formation ◽  
Cosmic String

scholarly journals COSMIC STRINGS, LOOPS, AND LINEAR GROWTH OF MATTER PERTURBATIONS

2002 ◽  
Vol 11 (01) ◽  
pp. 61-102 ◽  
Author(s):  
JIUN-HUEI PROTY WU ◽  
PEDRO P. AVELINO ◽  
E. P. S. SHELLARD ◽  
BRUCE ALLEN
Keyword(s):  
Dark Matter ◽  
Structure Formation ◽  
Cosmic String ◽  
Cold Dark Matter ◽  
Cosmic Strings ◽  
Topological Analysis ◽  
Long Strings ◽  
Source Spectrum ◽  
Galaxy Surveys ◽  
Network Properties

We describe a detailed study of string-seeded structure formation using high resolution numerical simulations in open universes and those with a non-zero cosmological constant. We provide a semi-analytical model which can reproduce these simulation results including the effect from small loops chopped of by the string network. A detailed study of cosmic string network properties regarding structure formation is also given, including the correlation time, the topological analysis of the source spectrum, the correlation between long strings and loops, and the evolution of long-string and loop energy densities. For models with Γ=Ω h=0.1 -0.2 and a cold dark matter background, we show that the linear density fluctuation power spectrum induced by cosmic strings has both an amplitude at 8 h-1 Mpc, σ8, and an overall shape which are consistent within uncertainties with those currently inferred from galaxy surveys. The cosmic string scenario with hot dark matter requires a strongly scale-dependent bias in order to agree with observations.

scholarly journals Dark matter distribution induced by a cosmic string wake in the nonlinear regime

2018 ◽  
Vol 98 (8) ◽  
Author(s):  
Disrael Camargo Neves da Cunha ◽  
Joachim Harnois-Deraps ◽  
Robert Brandenberger ◽  
Adam Amara ◽  
Alexandre Refregier
Keyword(s):  
Dark Matter ◽  
Cosmic String ◽  
Nonlinear Regime ◽  
Matter Distribution ◽  
Dark Matter Distribution

scholarly journals Collisionless Dynamics and the Cosmic Web

2014 ◽  
Vol 11 (S308) ◽  
pp. 87-96
Author(s):  
Oliver Hahn
Keyword(s):  
Dark Matter ◽  
Structure Formation ◽  
Large Scale ◽  
Velocity Potential ◽  
Three Dimensional ◽  
Maximum Amount ◽  
Lagrangian Manifold ◽  
Linear Regime ◽  
Fine Grained ◽  
Simulation Techniques

AbstractI review the nature of three-dimensional collapse in the Zeldovich approximation, how it relates to the underlying nature of the three-dimensional Lagrangian manifold and naturally gives rise to a hierarchical structure formation scenario that progresses through collapse from voids to pancakes, filaments and then halos. I then discuss how variations of the Zeldovich approximation (based on the gravitational or the velocity potential) have been used to define classifications of the cosmic large-scale structure into dynamically distinct parts. Finally, I turn to recent efforts to devise new approaches relying on tessellations of the Lagrangian manifold to follow the fine-grained dynamics of the dark matter fluid into the highly non-linear regime and both extract the maximum amount of information from existing simulations as well as devise new simulation techniques for cold collisionless dynamics.

scholarly journals Decaying warm dark matter and structure formation

2018 ◽  
Vol 2018 (12) ◽  
pp. 026-026 ◽  
Author(s):  
Jui-Lin Kuo ◽  
Massimiliano Lattanzi ◽  
Kingman Cheung ◽  
José W.F. Valle
Keyword(s):  
Dark Matter ◽  
Structure Formation

scholarly journals Braneworld model of dark matter: structure formation

2011 ◽  
Vol 44 (3) ◽  
pp. 581-601 ◽  
Author(s):  
Miguel A. García-Aspeitia ◽  
Juan A. Magaña ◽  
Tonatiuh Matos
Keyword(s):  
Dark Matter ◽  
Structure Formation ◽  
Braneworld Model

scholarly journals The holographic spacetime model of cosmology

2018 ◽  
Vol 27 (14) ◽  
pp. 1846005 ◽  
Author(s):  
Tom Banks ◽  
W. Fischler
Keyword(s):  
Dark Matter ◽  
Gravitational Waves ◽  
Structure Formation ◽  
Big Bang ◽  
Baryon Asymmetry ◽  
Gaussian Fluctuations ◽  
Primordial Gravitational Waves ◽  
Conventional Models ◽  
Non Gaussian ◽  
The Big Bang

This essay outlines the Holographic Spacetime (HST) theory of cosmology and its relation to conventional theories of inflation. The predictions of the theory are compatible with observations, and one must hope for data on primordial gravitational waves or non-Gaussian fluctuations to distinguish it from conventional models. The model predicts an early era of structure formation, prior to the Big Bang. Understanding the fate of those structures requires complicated simulations that have not yet been done. The result of those calculations might falsify the model, or might provide a very economical framework for explaining dark matter and the generation of the baryon asymmetry.

scholarly journals Impact of dark matter models on the EoR 21-cm signal bispectrum

2020 ◽  
Vol 497 (3) ◽  
pp. 2941-2953 ◽  
Author(s):  
Anchal Saxena ◽  
Suman Majumdar ◽  
Mohd Kamran ◽  
Matteo Viel
Keyword(s):  
Dark Matter ◽  
Structure Formation ◽  
Cold Dark Matter ◽  
Power Spectra ◽  
Neutral Hydrogen ◽  
Cosmic Time ◽  
Lower Number ◽  
Neutral Fraction ◽  
Small Scales ◽  
Low Mass

ABSTRACT The nature of dark matter sets the timeline for the formation of first collapsed haloes and thus affects the sources of reionization. Here, we consider two different models of dark matter: cold dark matter (CDM) and thermal warm dark matter (WDM), and study how they impact the epoch of reionization (EoR) and its 21-cm observables. Using a suite of simulations, we find that in WDM scenarios, the structure formation on small scales gets suppressed, resulting in a smaller number of low-mass dark matter haloes compared to the CDM scenario. Assuming that the efficiency of sources in producing ionizing photons remains the same, this leads to a lower number of total ionizing photons produced at any given cosmic time, thus causing a delay in the reionization process. We also find visual differences in the neutral hydrogen (H i) topology and in 21-cm maps in case of the WDM compared to the CDM. However, differences in the 21-cm power spectra, at the same neutral fraction, are found to be small. Thus, we focus on the non-Gaussianity in the EoR 21-cm signal, quantified through its bispectrum. We find that the 21-cm bispectra (driven by the H i topology) are significantly different in WDM models compared to the CDM, even for the same mass-averaged neutral fractions. This establishes that the 21-cm bispectrum is a unique and promising way to differentiate between dark matter models, and can be used to constrain the nature of the dark matter in the future EoR observations.

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