scholarly journals Gravitational Lensing by Dark Matter Halos with Nonuniversal Density Profiles

2004 ◽  
Vol 602 (1) ◽  
pp. L5-L8 ◽  
Author(s):  
Tong-Jie Zhang
Keyword(s):  
Dark Matter ◽  
Gravitational Lensing ◽  
Dark Matter Halos ◽  
Density Profiles

scholarly journals Structure of Dark Matter Halo

1999 ◽  
Vol 183 ◽  
pp. 155-155
Author(s):  
Toshiyuki Fukushige ◽  
Junichiro Makino
Keyword(s):  
Dark Matter ◽  
Cold Dark Matter ◽  
Temperature Inversion ◽  
Dark Matter Halo ◽  
Temperature Structure ◽  
Galactic Halos ◽  
Dark Matter Halos ◽  
Density Profiles ◽  
Order Of Magnitude ◽  
Special Purpose Computer

We performed N-body simulation on special-purpose computer, GRAPE-4, to investigate the structure of dark matter halos (Fukushige, T. and Makino, J. 1997, ApJL, 477, L9). Universal profile proposed by Navarro, Frenk, and White (1996, ApJ, 462, 563), which has cusp with density profiles ρ ∝r−1in density profile, cannot be reproduced in the standard Cold Dark Matter (CDM) picture of hierarchical clustering. Previous claims to the contrary were based on simulations with relatively few particles, and substantial softening. We performed simulations with particle numbers an order of magnitude higher, and essentially no softening, and found that typical central density profiles are clearly steeper than ρ ∝r−1, as shown in Figure 1. In addition, we confirm the presence of a temperature inversion in the inner 5 kpc of massive galactic halos, and give a natural explanation for formation of the temperature structure.

Statistics of Dark Matter Halos from Gravitational Lensing

2000 ◽  
Vol 530 (1) ◽  
pp. L1-L4 ◽  
Author(s):  
Bhuvnesh Jain ◽  
Ludovic Van Waerbeke
Keyword(s):  
Dark Matter ◽  
Gravitational Lensing ◽  
Dark Matter Halos

scholarly journals Testing Gravity using Void Profiles

2014 ◽  
Vol 11 (S308) ◽  
pp. 555-560 ◽  
Author(s):  
Yan-Chuan Cai ◽  
Nelson Padilla ◽  
Baojiu Li
Keyword(s):  
Dark Matter ◽  
Gravitational Lensing ◽  
Modified Gravity ◽  
Large Scale ◽  
Line Of Sight ◽  
Number Density ◽  
Density Profiles ◽  
Photometric Redshift ◽  
Redshift Survey ◽  
Near Future

AbstractWe investigate void properties inf(R)models using N-body simulations, focusing on their differences from General Relativity (GR) and their detectability. In the Hu-Sawickif(R)modified gravity (MG) models, the halo number density profiles of voids are not distinguishable from GR. In contrast, the samef(R)voids are more empty of dark matter, and their profiles are steeper. This can in principle be observed by weak gravitational lensing of voids, for which the combination of a spectroscopic redshift and a lensing photometric redshift survey over the same sky is required. Neglecting the lensing shape noise, thef(R)model parameter amplitudesfR0=10-5and 10-4may be distinguished from GR using the lensing tangential shear signal around voids by 4 and 8 σ for a volume of 1 (Gpc/h)3. The line-of-sight projection of large-scale structure is the main systematics that limits the significance of this signal for the near future wide angle and deep lensing surveys. For this reason, it is challenging to distinguishfR0=10-6from GR. We expect that this can be overcome with larger volume. The halo void abundance being smaller and the steepening of dark matter void profiles inf(R)models are unique features that can be combined to break the degeneracy betweenfR0and σ8.

scholarly journals THE ASYMPTOTIC STRUCTURE OF SPACE-TIME

2003 ◽  
Vol 12 (09) ◽  
pp. 1743-1750 ◽  
Author(s):  
FRED C. ADAMS ◽  
MICHAEL T. BUSHA ◽  
AUGUST E. EVRARD ◽  
RISA H. WECHSLER
Keyword(s):  
Dark Matter ◽  
Vacuum Energy ◽  
Space Time ◽  
Dark Matter Halo ◽  
Constant Density ◽  
Dark Matter Halos ◽  
Asymptotic Structure ◽  
Density Profiles ◽  
Near Future ◽  
Universal Geometry

Astronomical observations strongly suggest that our universe is now accelerating and contains a substantial admixture of dark vacuum energy. Using numerical simulations to study this newly consolidated cosmological model (with a constant density of dark energy), we show that astronomical structures freeze out in the near future and that the density profiles of dark matter halos approach the same general form. Every dark matter halo grows asymptotically isolated and thereby becomes the center of its own island universe. Each of these isolated regions of space-time approaches a universal geometry and we calculate the corresponding form of the space-time metric.

Dark Matter

2018 ◽  
pp. 169-174
Author(s):  
Alvaro De Rújula
Keyword(s):  
General Relativity ◽  
Dark Matter ◽  
Solar Eclipse ◽  
Gravitational Lensing ◽  
Virial Theorem ◽  
Dark Matter Halos ◽  
Gravitational Lenses ◽  
Coma Cluster ◽  
Cluster Of Galaxies ◽  
Galactic Dark Matter

What we know or do not know about dark matter. The evidence for its existence, first found by Fritz Zwicky. The “virial theorem” and the Coma cluster. The rotation curves of galaxies. Galactic dark-matter halos. Gravitational lensing and the May 1919 solar eclipse, a thiumph of General Relativity that propelled Einstein to his fame. The deflection of starlight by the eclipsed Sun. Gravitational lenses, Einstein rings, and Smilie. Gravitational-lensing and evidence for dark matter in the Bullet cluster of galaxies.

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