scholarly journals Properties of galaxy dark matter halos from weak lensing

2004 ◽  
Vol 220 ◽  
pp. 439-445 ◽  
Author(s):  
Henk Hoekstra ◽  
Howard K.C. Yee ◽  
Michael D. Gladders
Keyword(s):  
Dark Matter ◽  
Numerical Simulations ◽  
Excellent Agreement ◽  
Gravitational Lensing ◽  
Strong Support ◽  
Alternative Theories Of Gravity ◽  
Dark Matter Halos ◽  
Imaging Data ◽  
Average Mass ◽  
Theories Of Gravity

We present the results of a study of the average mass profile around galaxies using weak gravitational lensing. We use 45.5 deg2 of RC band imaging data from the Red-Sequence Cluster Survey (RCS) and define a sample of ~ 1.2 × 105 lenses with 19.5 < RC < 21, and a sample of ~ 1.5 × 106 background galaxies with 21.5 < R < 24.We constrain the power law scaling relations between the B-band luminosity and the mass and size of the halo, and find that the results are in excellent agreement with observed luminosity–line-width relations. Under the assumption that the luminosity does not evolve with redshift, the best fit NFW model yields a mass M200 = (8.8±0.7) × 1011h–1M⊙ and a scale radius rs = I6.7+3.7–3.0h–1 kpc for a galaxy with a fiducial luminosity of Lb = 1010h–2LB⊙. the latter result is in excellent agreement with predictions from numerical simulations for a halo of this mass. We also observe a signficant anisotropy of the lensing signal around the lenses, implying that the halos are flattened and aligned with the light distribution. We find an average (projected) halo ellipticity of 〈ehalo〉 = 0.20+0.04–0.05, in fair agreement with results from numerical simulations of CDM. Alternative theories of gravity (without dark matter) predict an isotropic lensing signal, which is excluded with 99.5% confidence. Hence, our results provide strong support for the existence of dark matter.

scholarly journals Rotation of Galaxy Dark Matter Halos

2006 ◽  
Vol 2 (S235) ◽  
pp. 104-104
Author(s):  
Stéphane Herbert-Fort ◽  
Dennis Zaritsky ◽  
Yeun Jin Kim ◽  
Jeremy Bailin ◽  
James E. Taylor
Keyword(s):  
Dark Matter ◽  
Angular Momentum ◽  
Numerical Simulations ◽  
Galaxy Formation ◽  
Spiral Galaxy ◽  
Observational Studies ◽  
Spiral Galaxies ◽  
Satellite System ◽  
Dark Matter Halos ◽  
The Mean

AbstractThe degree to which outer dark matter halos of spiral galaxies rotate with the disk is sensitive to their accretion history and may be probed with associated satellite galaxies. We use the Steward Observatory Bok telescope to measure the sense of rotation of nearby isolated spirals and combine these data with those of their associated satellites (drawn from SDSS) to directly test predictions from numerical simulations. We aim to constrain models of galaxy formation by measuring the projected component of the halo angular momentum that is aligned with that of spiral galaxy disks, Jz. We find the mean bulk rotation of the ensemble satellite system to be co-rotating with the disk with a velocity of 22 ± 13 km/s, in general agreement with previous observational studies and suggesting that galaxy disks could be formed by halo baryons collapsing by a factor of ≈10. We also find a prograde satellite fraction of 51% and Jz, of the satellite system to be positively correlated with the disk, albeit at low significance (2655 ± 2232 kpc km/s).

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

Dark matter and dark energy or alternative theories of gravity and cosmology

2008 ◽  
Author(s):  
Alexander F. Zakharov ◽  
Victor N. Pervushin ◽  
Francesco De Paolis ◽  
Gabriele Ingrosso ◽  
Achille A. Nucita ◽  
...  
Keyword(s):  
Dark Matter ◽  
Dark Energy ◽  
Alternative Theories Of Gravity ◽  
Theories Of Gravity ◽  
Alternative Theories

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 Building Galactic Disks in Triaxial Dark Matter Halos

2006 ◽  
Vol 2 (S235) ◽  
pp. 24-28
Author(s):  
Isaac Shlosman
Keyword(s):  
Dark Matter ◽  
Angular Momentum ◽  
Star Formation ◽  
Numerical Simulations ◽  
Recent Work ◽  
Stellar Evolution ◽  
Dark Matter Halos ◽  
Local Universe ◽  
Broad Agreement ◽  
Formation And Evolution

AbstractWe review our recent work on the formation and evolution of disks within triaxial dark matter (DM) halos by means of numerical simulations, including star formation and feedback from stellar evolution. The growing disks are strongly influenced by shapes of DM halos and modify them in turn. Disk parameters are in a broad agreement with those in the local universe. Gas-rich stellar bars grow in tandem with the disk and facilitate the angular momentum redistribution in the system and radial gas inflow. Nested bars appear to form as a by-product. Interactions between various non-axisymmetric components—bars, disks and halos lead to decay of bars or washing out of ellipticity in the inner halo.

scholarly journals Dark Matter Halos and the Main Sequence of Starforming Galaxies

2015 ◽  
Vol 11 (S319) ◽  
pp. 1-1
Author(s):  
Hervé Aussel ◽  
Sébastien Peirani ◽  
Laurent Vigroux
Keyword(s):  
Dark Matter ◽  
Star Formation ◽  
Numerical Simulations ◽  
Power Law ◽  
Main Sequence ◽  
Star Formation Rate ◽  
Formation Rate ◽  
Stellar Mass ◽  
Dark Matter Halos ◽  
Star Forming

AbstractWe investigate why hydrodynamical numerical simulations have difficulties (Weinmann et al. 2011) in reproducing the Main Sequence (MS) of star-forming galaxies, i.e. the fact that galaxies forming stars lie on a tight power law sequence in the stellar mass (M*), star formation rate (SFR) plane (Schreiber et al. 2015). Instead of trying to improve the agreement of simulations with the observations by modifying the subgrid recipes of baryons, we take here a step back to check whether the accretion onto dark matter halos is consistent with the existence of the main sequence of star forming galaxies.

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