scholarly journals GRAVITATIONAL WAVE ENHANCEMENT AS A TOOL TO DISTINGUISH DARK MATTER HALO PROFILES

2019 ◽  
Vol 55 (2) ◽  
pp. 231-235
Author(s):  
Sergio Grijalva Castillo ◽  
Carlos Calcáneo-Roldán
Keyword(s):  
Dark Matter ◽  
Gravitational Lensing ◽  
Dark Matter Halo ◽  
Spherically Symmetric ◽  
Dark Matter Halos ◽  
Recent Success ◽  
Galactic Dark Matter ◽  
Matter Model ◽  
Invaluable Tool ◽  
Dark Matter Model

The recent success of the dark matter model has proven to be an invaluable tool for describing the formation, evolution and stability of galaxies. In this work we study the enhancement function, F , of the gravitational lensing of gravitational waves by galactic dark matter halos and show how this function may be used to distinguish between halo models. In particular we compare an isothermal sphere with an NFW type density distribution, both of which are assumed to be spherically symmetric, and find that our technique clearly distinguishes between the models.

Rotation Curve and Dark Matter Halo profile in Finsler Geometry

2020 ◽  
Author(s):  
Nupur Paul ◽  
Farook Rahaman ◽  
Nasarul Islam ◽  
S.S. De
Keyword(s):  
Dark Matter ◽  
Rotational Velocity ◽  
Finsler Geometry ◽  
Outer Region ◽  
Recent Time ◽  
Dark Matter Halo ◽  
Dark Matter Halos ◽  
Radial Profiles ◽  
Galactic Dark Matter ◽  
Specific Equation

Galactic dark matter is an active area of research in recent time. Several researchers proposed several descriptions of radial profiles of dark matter halos by using N-body simulations. Among them, Navarro, Frenk and White (NFW) dark matter profile provides the most accurate description of dark matter halos. It is believed that dark matter is smooth and distributed uniformly throughout space. Using Finslerian geometrical background and a specific equation of state, we propose a new way to estimate the rotational velocity of galaxies based on the NFW dark matter profile. On small scales the first few distances (about 30 kpc) the velocity increases whereas in the outer region of the galaxies, the rotational velocity is found to be more or less constant which supports observed rotational velocities.

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.

scholarly journals Ellipticity of brightest cluster galaxies as tracer of halo orientation and weak-lensing mass bias

2019 ◽  
Vol 490 (4) ◽  
pp. 4889-4897 ◽  
Author(s):  
Ricardo Herbonnet ◽  
Anja von der Linden ◽  
Steven W Allen ◽  
Adam B Mantz ◽  
Pranati Modumudi ◽  
...  
Keyword(s):  
Dark Matter ◽  
Cold Dark Matter ◽  
Dark Matter Halo ◽  
Weak Lensing ◽  
Cluster Galaxies ◽  
Mass Bias ◽  
Brightest Cluster Galaxies ◽  
Cold Dark Matter Model ◽  
Matter Model ◽  
Dark Matter Model

ABSTRACT Weak-lensing measurements of the masses of galaxy clusters are commonly based on the assumption of spherically symmetric density profiles. Yet, the cold dark matter model predicts the shapes of dark matter haloes to be triaxial. Halo triaxiality, and the orientation of the major axis with respect to the line of sight, are expected to be the leading cause of intrinsic scatter in weak-lensing mass measurements. The shape of central cluster galaxies (brightest cluster galaxies; BCGs) is expected to follow the shape of the dark matter halo. Here we investigate the use of BCG ellipticity as predictor of the weak-lensing mass bias in individual clusters compared to the mean. Using weak-lensing masses $M^{\rm WL}_{500}$ from the Weighing the Giants project, and M500 derived from gas masses as low-scatter mass proxy, we find that, on average, the lensing masses of clusters with the roundest/most elliptical 25 per cent of BCGs are biased ∼20 per cent high/low compared to the average, as qualitatively predicted by the cold dark matter model. For cluster cosmology projects utilizing weak-lensing mass estimates, the shape of the BCG can thus contribute useful information on the effect of orientation bias in weak-lensing mass estimates as well as on cluster selection bias.

scholarly journals Galaxy Halo Masses from Weak Gravitational Lensing

2014 ◽  
Vol 10 (S311) ◽  
pp. 86-95 ◽  
Author(s):  
Rachel Mandelbaum
Keyword(s):  
Dark Matter ◽  
Gravitational Lensing ◽  
Dark Matter Halo ◽  
Dark Matter Halos ◽  
Weak Gravitational Lensing ◽  
Galaxy Halo ◽  
Halo Masses ◽  
The Masses ◽  
The Relationship ◽  
Intrinsic Scatter

AbstractIn this review, I discuss the use of galaxy-galaxy weak lensing measurements to study the masses of dark matter halos in which galaxies reside. After summarizing how weak gravitational lensing measurements can be interpreted in terms of halo mass, I review measurements that were used to derive the relationship between optical galaxy mass tracers, such as stellar mass or luminosity, and dark matter halo mass. Measurements of galaxy-galaxy lensing from the past decade have led to increasingly tight constraints on the connection between dark matter halo mass and optical mass tracers, including both the mean relationships between these quantities and the intrinsic scatter between them. I also review some of the factors that can complicate analysis, such as the choice of modeling procedure, and choices made when dividing up samples of lens galaxies.

Constraints on the Warm Dark Matter Model from Gravitational Lensing

2001 ◽  
Vol 549 (1) ◽  
pp. L21-L23 ◽  
Author(s):  
Yan-Jie Xue ◽  
Xiang-Ping Wu
Keyword(s):  
Dark Matter ◽  
Gravitational Lensing ◽  
Matter Model ◽  
Dark Matter Model

scholarly journals Triaxial versus Spherical Dark Matter Halo Profiles

2006 ◽  
Vol 23 (3) ◽  
pp. 125-128 ◽  
Author(s):  
Alexander Knebe ◽  
Volkmar Wießner
Keyword(s):  
Dark Matter ◽  
Mass Distribution ◽  
Density Profile ◽  
Simple Formula ◽  
Dark Matter Halo ◽  
Spherically Symmetric ◽  
Dark Matter Halos ◽  
Spherical Shells ◽  
Arbitrary Axis ◽  
Inner Parts

AbstractWhen analyzing dark matter halos forming in cosmological n-body simulations, it is common practice to obtain the density profile utilizing spherical shells. However, it is also known that the systems under investigation are far from spherically symmetric but, rather, follow a triaxial mass distribution. In this study we present an estimator for the error introduced by spherically averaging an elliptical mass distribution. We systematically investigate the differences arising when using a triaxial density profile under the assumption of spherical symmetry. We show that the variance in the density can be as large as 50% in the outer parts of dark matter halos for extreme (but still credible) axis ratios of 0.55: 0.67: 1. The inner parts are less affected but still show a scatter at the 16% level for these prolate systems. For more moderate ellipticities, i.e. axis ratios of 0.73: 0.87: 1, the error is smaller but still as large as 10–20% depending on distance. We further provide a simple formula that allows estimation of this variance as a function of radius for arbitrary axis ratios. We conclude that highly prolate and/or oblate systems are better fit by analytical profiles that take into account the triaxial nature of cosmological objects.

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