scholarly journals Beyond single-stream with the Schrödinger method

2014 ◽  
Vol 11 (S308) ◽  
pp. 115-118
Author(s):  
Cora Uhlemann ◽  
Michael Kopp
Keyword(s):  
Dark Matter ◽  
Phase Space ◽  
Poisson Equation ◽  
Large Scale ◽  
Fluid Model ◽  
Numerical Technique ◽  
Analytical Tool ◽  
The Common ◽  
Large Scale Structure Formation ◽  
Space Description

AbstractWe investigate large scale structure formation of collisionless dark matter in the phase space description based on the Vlasov-Poisson equation. We present the Schrödinger method, originally proposed by \cite{WK93} as numerical technique based on the Schrödinger Poisson equation, as an analytical tool which is superior to the common standard pressureless fluid model. Whereas the dust model fails and develops singularities at shell crossing the Schrödinger method encompasses multi-streaming and even virialization.

scholarly journals Viscosity in cosmic fluids

2020 ◽  
Vol 80 (8) ◽  
Author(s):  
Pravin Kumar Natwariya ◽  
Jitesh R. Bhatt ◽  
Arun Kumar Pandey
Keyword(s):  
Dark Matter ◽  
Effective Viscosity ◽  
Large Scale ◽  
Significant Contribution ◽  
Viscosity Coefficient ◽  
Effective Theory ◽  
Viscous Effect ◽  
Dissipative Effects ◽  
Large Scale Structure Formation

Abstract The effective theory of large-scale structure formation based on $$\Lambda $$ΛCDM paradigm predicts finite dissipative effects in the resulting fluid equations. In this work, we study how viscous effect that could arise if one includes self-interaction among the dark-matter particles combines with the effective theory. It is shown that these two possible sources of dissipation can operate together in a cosmic fluid and the interplay between them can play an important role in determining dynamics of the cosmic fluid. In particular, we demonstrate that the viscosity coefficient due to self-interaction is added inversely with the viscosity calculated using effective theory of $$\Lambda $$ΛCDM model. Thus the larger viscosity has less significant contribution in the effective viscosity. Using the known bounds on $$\sigma /m$$σ/m for self-interacting darkmatter, where $$\sigma $$σ and m are the cross-section and mass of the dark-matter particles respectively, we discuss role of the effective viscosity in various cosmological scenarios.

Observational and astrophysical cosmology: 1980–2018

2019 ◽  
pp. 375-423
Author(s):  
Malcolm S. Longair
Keyword(s):  
Dark Matter ◽  
Dark Energy ◽  
Cosmological Constant ◽  
Large Scale ◽  
Cosmological Parameters ◽  
Semiconductor Detectors ◽  
Empirical Knowledge ◽  
Global Geometry ◽  
The Universe ◽  
Large Scale Structure Formation

Since 1980, our empirical knowledge of the universe has advanced tremendously and precision cosmology has become a reality. These developments have been largely technology-driven, the result of increased computer power, new generations of telescopes for all wavebands, new types of semiconductor detectors, such as CCDs, and major investments by many nations in superb observing facilities. The discipline also benefitted from the influx of experimental and theoretical physicists into the cosmological arena. The accuracy and reliability of the values of the cosmological parameters has improved dramatically, many of them now being known to about 1%. The ΛCDM model provides a remarkable fit to all the observational data, demonstrating that the cosmological constant is non-zero and that the global geometry of the universe is flat. The underlying physics of galaxy and large-scale structure formation has advanced dramatically and demonstrated the key roles played by dark matter and dark energy.

scholarly journals A Scalar Field Dark Matter Model and Its Role in the Large-Scale Structure Formation in the Universe

2012 ◽  
Vol 2012 ◽  
pp. 1-13 ◽  
Author(s):  
Mario A. Rodríguez-Meza
Keyword(s):  
Dark Matter ◽  
Scalar Field ◽  
Structure Formation ◽  
Large Scale ◽  
Large Scale Structure ◽  
Scale Structure ◽  
Matter Model ◽  
The Universe ◽  
Dark Matter Model ◽  
Large Scale Structure Formation

We present a model of dark matter based on scalar-tensor theory of gravity. With this scalar field dark matter model we study the non-linear evolution of the large-scale structures in the universe. The equations that govern the evolution of the scale factor of the universe are derived together with the appropriate Newtonian equations to follow the nonlinear evolution of the structures. Results are given in terms of the power spectrum that gives quantitative information on the large-scale structure formation. The initial conditions we have used are consistent with the so-called concordance ΛCDM model.

scholarly journals Surveying for Dwarf Galaxies Within Voids FN2 and FN8

2014 ◽  
Vol 11 (S308) ◽  
pp. 614-615
Author(s):  
Stephen McNeil ◽  
Chris Draper ◽  
J. Ward Moody
Keyword(s):  
Dark Matter ◽  
Galaxy Formation ◽  
Large Scale ◽  
Dwarf Galaxies ◽  
Low Density ◽  
Dark Matter Halos ◽  
Void Volumes ◽  
Four Square ◽  
Large Scale Structure Formation

AbstractThe presence or absence of dwarf galaxies with Mr' > -14 in low-density volumes correlates with dark matter halos and how they affect galaxy formation. We are conducting a redshifted Hα imaging survey for dwarf galaxies with Mr' > -13 in the heart of the well-defined voids FN2 and FN8 using the KPNO 4m Mayall telescope and Mosaic Imager. These data have furnished over 600 strong candidates in a four square degree area. Follow-up spectra finding none of these candidates to be within the void volumes will constrain the dwarf population there to be 2 to 8% of the cosmic mean. Conversely, finding even one Hα dwarf in the void heart will challenge several otherwise successful theories of large-scale structure formation.

scholarly journals Dark atoms with nuclear shell: A status review

2015 ◽  
Vol 24 (13) ◽  
pp. 1545007 ◽  
Author(s):  
J. R. Cudell ◽  
M. Khlopov
Keyword(s):  
Dark Matter ◽  
Large Scale ◽  
Cold Dark Matter ◽  
New Physics ◽  
Helium Nucleus ◽  
Potential Problems ◽  
Doubly Charged ◽  
Nuclear Shell ◽  
Direct Dark Matter ◽  
Large Scale Structure Formation

Among dark atom scenarios, the simplest and most predictive one is that of O-helium (OHe) dark atoms, in which a leptonlike doubly charged particle O–– is bound to a primordial helium nucleus, and is the main constituent of dark matter. The OHe cosmology has several successes: it leads to a warmer-than-cold-dark matter scenario for large-scale-structure formation, it can provide an explanation for the excess in positron annihilation line in the galactic bulge and it may explain the results of direct dark matter searches. This model liberates the physics of dark atoms from many unknown features of new physics, but it is still not free from astrophysical uncertainties. It also demands a deeper understanding of the details of known nuclear and atomic physics, which are still somewhat unclear in the case of nuclear interacting “atomic” shells. These potential problems of the OHe scenario are also discussed.

Student Perceptions of Community: A Different Perspective

NASPA Journal ◽  
1998 ◽  
Vol 35 (4) ◽  
Author(s):  
Jackie Clark ◽  
Joan Hirt
Keyword(s):  
Student Perceptions ◽  
Large Scale ◽  
Research University ◽  
Small Scale ◽  
Social Environments ◽  
Common Assumption ◽  
Small Communities ◽  
Public Research University ◽  
The Common ◽  
Using Data

The creation of small communities has been proposed as a way of enhancing the educational experience of students at large institutions. Using data from a survey of students living in large and small residences at a public research university, this study does not support the common assumption that small-scale social environments are more conducive to positive community life than large-scale social environments.

scholarly journals Shell-crossing in a ΛCDM Universe

2020 ◽  
Vol 501 (1) ◽  
pp. L71-L75
Author(s):  
Cornelius Rampf ◽  
Oliver Hahn
Keyword(s):  
Dark Matter ◽  
Perturbation Theory ◽  
Large Scale ◽  
Cold Dark Matter ◽  
Three Dimensional ◽  
Random Initial Data ◽  
Recursion Relations ◽  
Indispensable Tool ◽  
First Time ◽  
Very High

ABSTRACT Perturbation theory is an indispensable tool for studying the cosmic large-scale structure, and establishing its limits is therefore of utmost importance. One crucial limitation of perturbation theory is shell-crossing, which is the instance when cold-dark-matter trajectories intersect for the first time. We investigate Lagrangian perturbation theory (LPT) at very high orders in the vicinity of the first shell-crossing for random initial data in a realistic three-dimensional Universe. For this, we have numerically implemented the all-order recursion relations for the matter trajectories, from which the convergence of the LPT series at shell-crossing is established. Convergence studies performed at large orders reveal the nature of the convergence-limiting singularities. These singularities are not the well-known density singularities at shell-crossing but occur at later times when LPT already ceased to provide physically meaningful results.

Sign in / Sign up

Export Citation Format

Share Document