scholarly journals Imprints of dark energy on cosmic structure formation – III. Sparsity of dark matter halo profiles

2013 ◽  
Vol 437 (3) ◽  
pp. 2328-2339 ◽  
Author(s):  
I. Balmès ◽  
Y. Rasera ◽  
P.-S. Corasaniti ◽  
J.-M. Alimi
2016 ◽  
Vol 26 (07) ◽  
pp. 1750063 ◽  
Author(s):  
Arata Aoki ◽  
Jiro Soda

The ultralight axion with mass around [Formula: see text][Formula: see text]eV is known as a candidate of dark matter. A peculiar feature of the ultralight axion is oscillating pressure in time, which produces oscillation of gravitational potentials. Since the solar system moves through the dark matter halo at the velocity of about [Formula: see text], there exists axion wind, which looks like scalar gravitational waves for us. Hence, there is a chance to detect ultralight axion dark matter with a wide mass range by using laser interferometer detectors. We calculate the detector signal induced by the oscillating pressure of the ultralight axion field, which would be detected by future laser interferometer experiments. We also argue that the detector signal can be enhanced due to the resonance in modified gravity theory explaining the dark energy.


Author(s):  
Jian-Bin Bao ◽  
Nicholas Bao

There are unsolved problems related to inflation, gravity, dark matter, dark energy, and the fate of the universe. Some of them can be better answered by assuming the existence of aether and hypoatoms. Both were created during the inflation in the very early universe. While aether forms vacuum, hypoatoms form all observable matter. In vacuum, aether exists between the particle-antiparticle form and the energy form in a dynamic equilibrium: A + A-bar = gamma + gamma, resulting in quantum phenomena and a character of negative pressure. The proposed hypoatom has an antimatter nucleus, with an equal mass of matter particles of aether in its perimeter, so the enigma of missing antimatter does not exist. At hypoatoms, the forward reaction of the aether annihilation dominates. With constant-density dark energy, the annihilation constantly consumes the aether in vacuum, producing a sink flow of aether that warps spacetime, and thus generates gravity and a dark matter halo in the vicinity of massive objects. The hypoatom is believed to be a neutrino n1, with a mass of 5 meV. Based on the hypoatom structure, singularities do not exist inside black holes; their cores are hypoatom stars or neutrino stars. By gaining enough mass, ca. , to exceed neutrino degeneracy pressure, a black hole collapses or annihilates into the singularity, thus turning itself into a white hole or a new Big Bang.


2020 ◽  
Vol 29 (14) ◽  
pp. 2043030
Author(s):  
Douglas Edmonds ◽  
Djordje Minic ◽  
Tatsu Takeuchi

We discuss the existence of an acceleration scale in galaxies and galaxy clusters and its relevance for the nature of dark matter. The presence of the same acceleration scale found at very different length scales, and in very different astrophysical objects, strongly supports the existence of a fundamental acceleration scale governing the observed gravitational physics. We comment on the implications of such a fundamental acceleration scale for constraining cold dark matter models as well as its relevance for structure formation to be explored in future numerical simulations.


Author(s):  
Rhys J J Poulton ◽  
Chris Power ◽  
Aaron S G Robotham ◽  
Pascal J Elahi

Abstract Hierarchical models of structure formation predict that dark matter halo assembly histories are characterised by episodic mergers and interactions with other haloes. An accurate description of this process will provide insights into the dynamical evolution of haloes and the galaxies that reside in them. Using large cosmological N-body simulations, we characterise halo orbits to study the interactions between substructure haloes and their hosts, and how different evolutionary histories map to different classes of orbits. We use two new software tools - WhereWolf, which uses halo group catalogues and merger trees to ensure that haloes are tracked accurately in dense environments, and OrbWeaver, which quantifies each halo’s orbital parameters. We demonstrate how WhereWolf improves the accuracy of halo merger trees, and we use OrbWeaver to quantify orbits of haloes. We assess how well analytical prescriptions for the merger timescale from the literature compare to measured merger timescales from our simulations and find that existing prescriptions perform well, provided the ratio of substructure-to-host mass is not too small. In the limit of small substructure-to-host mass ratio, we find that the prescriptions can overestimate the merger timescales substantially, such that haloes are predicted to survive well beyond the end of the simulation. This work highlights the need for a revised analytical prescription for the merger timescale that more accurately accounts for processes such as catastrophic tidal disruption.


2007 ◽  
Vol 16 (02n03) ◽  
pp. 453-461
Author(s):  
NILZA PIRES ◽  
HIDALYN T. C. M. DE SOUZA

In this work we present preliminary results of an analysis on the evolution of primordial baryonic and dark matter density perturbations. A top-hat hydrodynamic code has been utilized to analyze the evolution of these primordial perturbations, from the beginning of the recombination era until the redshift when the collapse occurs. All the relevant processes are included in the calculations, which includes the effect of a dark energy in the expanding universe. In particular, we find that the perturbations with dark matter collapse at very high redshift, which could explain the existence of old galaxies at high redshift. As a general result we find that the distribution of the non-baryonic dark matter is more concentrated than the baryonic one.


2020 ◽  
Vol 101 (4) ◽  
Author(s):  
Finlay Noble Chamings ◽  
Anastasios Avgoustidis ◽  
Edmund J. Copeland ◽  
Anne M. Green ◽  
Alkistis Pourtsidou

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