REEXAMINING THE UNIVERSALITY OF THE BURKERT PROFILE ON CLUSTER SCALES: DARK MATTER CORES

2001 ◽  
Vol 10 (02) ◽  
pp. 239-244
Author(s):  
YAN-JIE XUE ◽  
XIANG-PING WU
Keyword(s):  
Dark Matter ◽  
Cross Section ◽  
Gravitational Lensing ◽  
Surface Brightness ◽  
Matter Density ◽  
Great Success ◽  
Analytic Approximation ◽  
Dark Halo ◽  
X Ray ◽  
Strong Gravitational Lensing

The Burkert profile is a competing candidate for the analytic approximation of virialized dark halos especially when dark matter particles have a finite cross-section for elastic collisions. In this paper we reexamine its universality in massive systems, using an ensemble of 45 nearby X-ray clusters and 20 distant X-ray/lensing clusters. Despite the fact that this empirical profile turns out a great success on galactic scales and also reproduces approximately the X-ray observed surface brightness profiles of clusters, the dark matter cores of clusters predicted by the Burkert profile are too large to be reconciled with the strong gravitational lensing measurements. Specifically, the typical dark halo cores of clusters represented by the Burkert profile are about 0.2 Mpc, and only a small fraction (~1/4) of clusters can have compact cores smaller than 0.1 Mpc. This will constitute a critical challenge to the Burkert profile as a universal dark matter density law over entire mass ranges.

scholarly journals Determination of the local dark matter density using K-dwarfs from Gaia DR2

2020 ◽  
Vol 240 ◽  
pp. 04002
Author(s):  
M. Dafa Wardana ◽  
Hesti Wulandari ◽  
Sulistiyowati ◽  
Akbar H. Khatami
Keyword(s):  
Dark Matter ◽  
Galactic Disk ◽  
Matter Density ◽  
Solar Neighborhood ◽  
Stellar Disk ◽  
Vertical Position ◽  
Dark Halo ◽  
Detection Rates ◽  
Dark Matter Density ◽  
Gaia Dr2

Local dark matter density, ρdm, is one of the crucial astrophysical inputs for the estimation of detection rates in dark matter direct search experi- ments. Knowing the value also helps us to investigate the shape of the Galactic dark halo, which is of importance for indirect dark matter searches, as well as for various studies in astrophysics and cosmology. In this work, we performed kinematics study of stars in the solar neighborhood to determine the local dark matter density. As tracers we used 95,543 K-dwarfs from Gaia DR2 inside a heliocentric cylinder with a radius of 150 pc and height 200 pc above and below the Galactic mid plane. Their positions and motions were analyzed, assum- ing that the Galaxy is axisymmetric and the tracers are in dynamical equilib- rium. We applied Jeans and Poisson equations to relate the observed quantities, i.e. vertical position and velocity, with the local dark matter density. The tilt term in the Jeans equation is considered to be small and is therefore neglected. Galactic disk is modelled to consist of a single exponential stellar disk, a thin gas layer, and dark matter whose density is constant within the volume consid- ered. Marginalization for the free parameters was performed with Bayesian theorem using Markov Chain Monte Carlo (MCMC) method. We find that ρdm = 0.0116 ± 0.0012 MO/pc or ρdm = 0.439 ± 0.046 GeV/cm3, in agreement within the range of uncertainty with results of several previous studies.

scholarly journals ASCA Observations of Three Gravitational Lensing Clusters of Galaxies; CL0500-24, CL2244-02, and A370

1998 ◽  
Vol 188 ◽  
pp. 319-320
Author(s):  
Naomi Ota ◽  
Kazuhisa Mitsuda ◽  
Yasushi Fukazawa
Keyword(s):  
Gravitational Lensing ◽  
Surface Brightness ◽  
Clusters Of Galaxies ◽  
X Ray

We determined the X-ray temperatures of three gravitational lensing clusters, CL0500-24, CL2244-02, and A370, and obtained significant constraints on the surface brightness profile assuming the β-model and the King model profiles. The mass of the cluster estimated from these X-ray data is by a factor of two to three smaller than the mass estimated from lens models for two of the clusters.

scholarly journals Measuring the power spectrum of dark matter substructure using strong gravitational lensing

2016 ◽  
Vol 2016 (11) ◽  
pp. 048-048 ◽  
Author(s):  
Yashar Hezaveh ◽  
Neal Dalal ◽  
Gilbert Holder ◽  
Theodore Kisner ◽  
Michael Kuhlen ◽  
...  
Keyword(s):  
Dark Matter ◽  
Power Spectrum ◽  
Gravitational Lensing ◽  
Strong Gravitational Lensing

scholarly journals Investigating the Relationship Between the Hot Gas and the Dark Matter Components of Galaxy Clusters.

2007 ◽  
Vol 3 (S244) ◽  
pp. 374-375
Author(s):  
Leila C. Powell ◽  
Scott T. Kay ◽  
Arif Babul ◽  
Andisheh Mahdavi
Keyword(s):  
Dark Matter ◽  
Total Mass ◽  
Surface Brightness ◽  
Galaxy Cluster ◽  
Weak Lensing ◽  
X Ray ◽  
Hot Gas ◽  
Cluster Properties ◽  
The Impact ◽  
The Relationship

AbstractVarious differences in galaxy cluster properties derived from X-ray and weak lensing observations have been highlighted in the literature. One such difference is the observation of mass concentrations in lensing maps which have no X-ray counterparts (e.g. Jee, White, Ford et al. 2005). We investigate this issue by identifying substructures in maps of projected total mass (analogous to weak lensing mass reconstructions) and maps of projected X-ray surface brightness for three simulated clusters. We then compare the 2D mass substructures with both 3D subhalo data and the 2D X-ray substructures. Here we present preliminary results from the first comparison, where we have assessed the impact of projecting the data on subhalo identification.

scholarly journals Dark-Matter in Galaxies from Gravitational Lensing and Stellar Dynamics Studies

2009 ◽  
Vol 5 (H15) ◽  
pp. 74-74
Author(s):  
L. V. E. Koopmans
Keyword(s):  
Dark Matter ◽  
Mass Distribution ◽  
Density Profile ◽  
Gravitational Lensing ◽  
Total Mass ◽  
Stellar Dynamics ◽  
Early Type ◽  
Complementary Methods ◽  
Strong Gravitational Lensing

AbstractStrong gravitational lensing and stellar dynamics provide two complementary methods in the study of the mass distribution of dark matter in galaxies out to redshift of unity. They are particularly powerful in the determination of the total mass and the density profile of mass early-type galaxies on kpc to tens of kpc scales, and also reveal the presence of mass-substructure on sub-kpc scale. I will shortly discuss these topics in this review.

scholarly journals High accuracy analytical solutions for the projected mass (counts) & surface density (brightness) of Einasto profiles

2021 ◽  
Author(s):  
Barun K Dhar
Keyword(s):  
Dark Matter ◽  
Gravitational Lensing ◽  
Surface Density ◽  
Surface Brightness ◽  
Analytical Approximation ◽  
High Accuracy ◽  
Density Profiles ◽  
Massive Galaxies ◽  
Multiple Components ◽  
Number Counts

Abstract The Einasto profile has been successful in describing the density profiles of dark matter haloes in ΛCDM N-body simulations. It has also been able to describe multiple components in the surface brightness profiles of galaxies. However, analytically projecting it to calculate quantities under projection is challenging. In this paper, we will see the development of a highly accurate analytical approximation for the mass (or counts) enclosed in an infinitely long cylindrical column for Einasto profiles—also known as the projected mass (or counts)—using a novel methodology. We will then develop a self-consistent high accuracy model for the surface density from the expression for the projected mass. Both models are quite accurate for a broad family of functions, with a shape parameter α varying by a factor of 100 in the range 0.05 ≲ α ≲ 5.0, with fractional errors ∼10−6 for α ≲ 0.4. Profiles with α ≲ 0.4 have been shown to fit the density profiles of dark matter haloes in N-body simulations as well as the luminosity profiles of the outer components of massive galaxies. Since the projected mass and the surface density are used in gravitational lensing, I will illustrate how these models facilitate (for the first time) analytical computation of several quantities of interest in lensing due to Einasto profiles. The models, however, are not limited to lensing and apply to similar quantities under projection, such as the projected luminosity, the projected (columnar) number counts and the projected density or the surface brightness.

scholarly journals The Dark Matter, Gas, and Galaxy Distributions in Abell 2218: A Weak Gravitational Lensing and X-Ray Analysis

1996 ◽  
Vol 461 ◽  
pp. 572 ◽  
Author(s):  
G. Squires ◽  
N. Kaiser ◽  
A. Babul ◽  
G. Fahlman ◽  
D. Woods ◽  
...  
Keyword(s):  
Dark Matter ◽  
Gravitational Lensing ◽  
Weak Gravitational Lensing ◽  
X Ray
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