Measuring the Mass and Concentration of Dark Matter Halos from the Velocity Dispersion Profile of their Stars

N-body simulations of dark matter halos show that the density profiles of the halos behave as ρ(r) ∝ r-α(r), where the density logarithmic slope α ≃ 1–1.5 in the center and α ≃ 3–4 in the outer parts of the halos. However, some observations are not in agreement with simulations in the very central region of the halos. The simulations also show that the velocity dispersion anisotropy parameter β ≈ 0 in the inner part of the halo and the so-called pseudo–phase-space density ρ/σ3 behaves as a power law in radius r. With these results in mind, we study the distribution function and the pseudo–phase-space density ρ/σ3 of the center of dark matter halos and find that they are closely related.

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CLASH-VLT: a full dynamical reconstruction of the mass profile of Abell S1063 from 1 kpc out to the virial radius

Astronomy and Astrophysics ◽

10.1051/0004-6361/202037521 ◽

2020 ◽

Vol 637 ◽

pp. A34 ◽

Cited By ~ 3

Author(s):

B. Sartoris ◽

A. Biviano ◽

P. Rosati ◽

A. Mercurio ◽

C. Grillo ◽

...

Keyword(s):

Dark Matter ◽

Density Profile ◽

Velocity Dispersion ◽

Mass Density ◽

Dynamical Analysis ◽

Cluster Galaxy ◽

Data Set ◽

Density Profiles ◽

Dispersion Profile ◽

Mass Profile

Context. The shape of the mass density profiles of cosmological halos informs us of the nature of dark matter (DM) and DM-baryons interactions. Previous estimates of the inner slope of the mass density profiles of clusters of galaxies are in opposition to predictions derived from numerical simulations of cold dark matter (CDM). Aims. We determine the inner slope of the DM density profile of a massive cluster of galaxies, Abell S1063 (RXC J2248.7−4431) at z = 0.35, with a dynamical analysis based on an extensive spectroscopic campaign carried out with the VIMOS and MUSE spectrographs at the ESO VLT. This new data set provides an unprecedented sample of 1234 spectroscopic members, 104 of which are located in the cluster core (R ≲ 200 kpc), extracted from the MUSE integral field spectroscopy. The latter also allows the stellar velocity dispersion profile of the brightest cluster galaxy (BCG) to be measured out to 40 kpc. Methods. We used an upgraded version of the MAMPOSSt technique to perform a joint maximum likelihood fit to the velocity dispersion profile of the BCG and to the velocity distribution of cluster member galaxies over a radial range from 1 kpc to the virial radius (r200 ≈ 2.7 Mpc). Results. We find a value of γDM = 0.99 ± 0.04 for the inner logarithmic slope of the DM density profile after marginalizing over all the other parameters of the mass and velocity anisotropy models. Moreover, the newly determined dynamical mass profile is found to be in excellent agreement with the mass density profiles obtained from the independent X-ray hydrostatic analysis based on deep Chandra data, as well as the strong and weak lensing analyses. Conclusions. Our value of the inner logarithmic slope of the DM density profile γDM is in very good agreement with predictions from cosmological CDM simulations. We will extend our analysis to more clusters in future works. If confirmed on a larger cluster sample, our result makes this DM model more appealing than alternative models.

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STELLAR MASS VERSUS STELLAR VELOCITY DISPERSION: WHICH IS BETTER FOR LINKING GALAXIES TO THEIR DARK MATTER HALOS?

The Astrophysical Journal ◽

10.1088/2041-8205/762/1/l7 ◽

2012 ◽

Vol 762 (1) ◽

pp. L7 ◽

Cited By ~ 10

Author(s):

Cheng Li ◽

Lixin Wang ◽

Y. P. Jing

Keyword(s):

Dark Matter ◽

Velocity Dispersion ◽

Stellar Mass ◽

Dark Matter Halos ◽

Stellar Velocity

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Stellar Velocity Dispersion: Linking Quiescent Galaxies to Their Dark Matter Halos

The Astrophysical Journal ◽

10.3847/1538-4357/aabe31 ◽

2018 ◽

Vol 859 (2) ◽

pp. 96 ◽

Cited By ~ 10

Author(s):

H. Jabran Zahid ◽

Jubee Sohn ◽

Margaret J. Geller

Keyword(s):

Dark Matter ◽

Velocity Dispersion ◽

Dark Matter Halos ◽

Stellar Velocity

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Limits on the dark matter content of globular clusters

Proceedings of the International Astronomical Union ◽

10.1017/s174392130999130x ◽

2009 ◽

Vol 5 (S266) ◽

pp. 365-365

Author(s):

H. Baumgardt ◽

P. Côté ◽

M. Hilker ◽

M. Rejkuba ◽

S. Mieske ◽

...

Keyword(s):

Dark Matter ◽

Globular Clusters ◽

Stellar Population ◽

Velocity Dispersion ◽

Large Mass ◽

Matter Content ◽

Dark Matter Halo ◽

Dark Matter Halos ◽

Galactocentric Distance ◽

Rule Out

AbstractWe have measured the velocity dispersion of the Galactic globular cluster NGC 2419 to determine if a substantial amount of dark matter is present in this cluster. NGC 2419 is one of the best globular clusters to look for dark matter due to its large mass, long relaxation time and large Galactocentric distance, which makes tidal stripping of dark matter unlikely. Our results can be summarized as follows. (i) We found a global velocity dispersion of 4.14 ± 0.48 km s−1, which leads to a total cluster mass of (9.02 ± 2.22) × 105 M⊙ and implies a global mass-to-light ratio of 2.05 ± 0.50 M⊙/L⊙. (ii) Our derived mass-to-light ratio is completely consistent with the mass-to-light ratio of a standard stellar population at the metallicity and age of NGC 2419. In addition, the mass-to-light ratio of NGC 2419 does not increase towards the outer cluster parts. (iii) We can therefore rule out the presence of a dark-matter halo with a central density greater than about 0.02 M⊙ pc−3. Similar limits are found for other halo globular clusters, like Pal 14. These observations therefore indicate that NGC 2419 and other halo globular clusters did not form at the centers of dark-matter halos similar to those surrounding dwarf galaxies. Instead, an origin driven by gas-dynamical processes during mergers between galaxies or proto-galactic fragments seems to be the more likely explanation for the formation of even the lowest-metallicity globular clusters.

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