Spatially Resolved Stellar Kinematics of the Ultra-diffuse Galaxy Dragonfly 44. I. Observations, Kinematics, and Cold Dark Matter Halo Fits

ABSTRACTDwarf spheroidal galaxies (dSphs) are the most compact dark-matter-dominated objects observed so far. The Pauli exclusion principle limits the number of fermionic dark matter particles that can compose a dSph halo. This results in a well-known lower bound on their particle mass. So far, such bounds were obtained from the analysis of individual dSphs. In this paper, we model dark matter halo density profiles via the semi-analytical approach and analyse the data from eight ‘classical’ dSphs assuming the same mass of dark matter fermion in each object. First, we find out that modelling of Carina dSph results in a much worse fitting quality compared to the other seven objects. From the combined analysis of the kinematic data of the remaining seven ‘classical’ dSphs, we obtain a new 2σ lower bound of m ≳ 190 eV on the dark matter fermion mass. In addition, by combining a sub-sample of four dSphs – Draco, Fornax, Leo I, and Sculptor – we conclude that 220 eV fermionic dark matter appears to be preferred over the standard cold dark matter at about the 2σ level. However, this result becomes insignificant if all seven objects are included in the analysis. Future improvement of the obtained bound requires more detailed data, both from ‘classical’ and ultra-faint dSphs.

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Structure of Dark Matter Halo

Symposium - International Astronomical Union ◽

10.1017/s0074180900132358 ◽

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.

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Cold Dark Matter Substructure and the Heating of Galactic Disks

Symposium - International Astronomical Union ◽

10.1017/s0074180900207419 ◽

2003 ◽

Vol 208 ◽

pp. 391-392

Author(s):

Andreea S. Font ◽

Julio F. Navarro

Keyword(s):

Dark Matter ◽

Cold Dark Matter ◽

Milky Way ◽

Dark Matter Halo ◽

Stellar Disk ◽

Minor Role ◽

Galactic Disks ◽

Cosmological Simulations ◽

A Minor

We investigate recent suggestions that substructure in cold dark matter (CDM) halos has potentially destructive effects on galactic disks. N-body simulations of disk/bulge models of the Milky Way, embedded in a dark matter halo with substructure similar to that found in cosmological simulations, show that tides from substructure halos play only a minor role in the dynamical heating of the stellar disk. This suggests that substructure might not preclude CDM halos from being acceptable hosts of thin stellar disks.

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High energy γ-ray lines: a probe for a cold dark matter halo

10.1063/1.40921 ◽

1991 ◽

Author(s):

Pierre Salati ◽

Pascal Chardonnet

Keyword(s):

Dark Matter ◽

Cold Dark Matter ◽

High Energy ◽

Dark Matter Halo ◽

Γ Ray

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Testing dark energy models with a new sample of strong-lensing systems

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/staa2760 ◽

2020 ◽

Vol 498 (4) ◽

pp. 6013-6033

Author(s):

Mario H Amante ◽

Juan Magaña ◽

V Motta ◽

Miguel A García-Aspeitia ◽

Tomás Verdugo

Keyword(s):

Dark Matter ◽

Cold Dark Matter ◽

Velocity Dispersion ◽

Cosmological Parameters ◽

Cosmic Acceleration ◽

Dark Matter Halo ◽

Measured Velocity ◽

Strong Lensing ◽

The Impact ◽

Einstein Radius

ABSTRACT Inspired by a new compilation of strong-lensing systems, which consist of 204 points in the redshift range 0.0625 < zl < 0.958 for the lens and 0.196 < zs < 3.595 for the source, we constrain three models that generate a late cosmic acceleration: the ω-cold dark matter model, the Chevallier–Polarski–Linder, and the Jassal–Bagla–Padmanabhan parametrizations. Our compilation contains only those systems with early-type galaxies acting as lenses, with spectroscopically measured stellar velocity dispersions, estimated Einstein radius, and both the lens and source redshifts. We assume an axially symmetric mass distribution in the lens equation, using a correction to alleviate differences between the measured velocity dispersion (σ) and the dark matter halo velocity dispersion (σDM) as well as other systematic errors that may affect the measurements. We have considered different subsamples to constrain the cosmological parameters of each model. Additionally, we generate a mock data of SLS to asses the impact of the chosen mass profile on the accuracy of Einstein radius estimation. Our results show that cosmological constraints are very sensitive to the selected data: Some cases show convergence problems in the estimation of cosmological parameters (e.g. systems with observed distance ratio Dobs < 0.5), others show high values for the χ2 function (e.g. systems with a lens equation Dobs > 1 or high velocity dispersion σ > 276 km s−1). However, we obtained a fiduciary sample with 143 systems, which improves the constraints on each tested cosmological model.

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The statistical properties of Λ cold dark matter halo formation

Monthly Notices of the Royal Astronomical Society ◽

10.1111/j.1365-2966.2007.12516.x ◽

2007 ◽

Vol 383 (2) ◽

pp. 546-556 ◽

Cited By ~ 61

Author(s):

Shaun Cole ◽

John Helly ◽

Carlos S. Frenk ◽

Hannah Parkinson

Keyword(s):

Dark Matter ◽

Cold Dark Matter ◽

Statistical Properties ◽

Dark Matter Halo ◽

Halo Formation

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On the origin of cold dark matter halo density profiles

Monthly Notices of the Royal Astronomical Society ◽

10.1111/j.1365-2966.2006.10270.x ◽

2006 ◽

Vol 368 (4) ◽

pp. 1931-1940 ◽

Cited By ~ 80

Author(s):

Y. Lu ◽

H. J. Mo ◽

N. Katz ◽

M. D. Weinberg

Keyword(s):

Dark Matter ◽

Cold Dark Matter ◽

Dark Matter Halo ◽

Density Profiles

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On the Shape of the Galactic Dark Matter Halo

Publications of the Astronomical Society of Australia ◽

10.1071/as04032 ◽

2004 ◽

Vol 21 (2) ◽

pp. 212-215 ◽

Cited By ~ 4

Author(s):

Amina Helmi

Keyword(s):

Dark Matter ◽

Numerical Simulations ◽

Cold Dark Matter ◽

Milky Way ◽

Dark Matter Halo ◽

Dark Halo ◽

Galactic Dark Matter ◽

Galactic Potentials ◽

Strong Contrast

AbstractThe confined nature of the debris from the Sagittarius dwarf to a narrow trail on the sky has recently prompted the suggestion that the dark matter halo of our Galaxy should be nearly spherical (Ibata et al. 2001; Majewski et al. 2003). This would seem to be in strong contrast with predictions from cold dark matter (CDM) simulations, where dark halos are found to have typical density axis ratios of 0.6 to 0.8. Here I present numerical simulations of the evolution of a system like the Sagittarius dSph in a set of Galactic potentials with varying degrees of flattening. These simulations show that the Sagittarius streams discovered so far are too young dynamically to be sensitive to the shape of the dark halo of the Milky Way. The data presently available are entirely consistent with a Galactic dark matter halo that could either be oblate or prolate, with density axis ratios c/a that range from 0.6 to 1.6 within the region of the halo probed by the orbit of the Sagittarius dwarf.

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