Globular clusters vs dark matter haloes in strong lensing observations

ABSTRACT Dynamical models allow us to connect the motion of a set of tracers to the underlying gravitational potential, and thus to the total (luminous and dark) matter distribution. They are particularly useful for understanding the mass and spatial distribution of dark matter (DM) in a galaxy. Globular clusters (GCs) are an ideal tracer population in dynamical models, since they are bright and can be found far out into the halo of galaxies. We aim to test how well Jeans-Anisotropic-MGE (JAM) models using GCs (positions and line-of-sight velocities) as tracers can constrain the mass and radial distribution of DM haloes. For this, we use the E-MOSAICS suite of 25 zoom-in simulations of L* galaxies. We find that the DM halo properties are reasonably well recovered by the JAM models. There is, however, a strong correlation between how well we recover the mass and the radial distribution of the DM and the number of GCs in the galaxy: the constraints get exponentially worse with fewer GCs, and at least 150 GCs are needed in order to guarantee that the JAM model will perform well. We find that while the data quality (uncertainty on the radial velocities) can be important, the number of GCs is the dominant factor in terms of the accuracy and precision of the measurements. This work shows promising results for these models to be used in extragalactic systems with a sample of more than 150 GCs.

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Evidence of a population of dark subhaloes from Gaia and Pan-STARRS observations of the GD-1 stream

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/stab210 ◽

2021 ◽

Vol 502 (2) ◽

pp. 2364-2380

Author(s):

Nilanjan Banik ◽

Jo Bovy ◽

Gianfranco Bertone ◽

Denis Erkal ◽

T J L de Boer

Keyword(s):

Dark Matter ◽

Mass Fraction ◽

Molecular Clouds ◽

Globular Clusters ◽

Cold Dark Matter ◽

Joint Analysis ◽

Giant Molecular Clouds ◽

Total Abundance ◽

Hydrodynamical Simulation ◽

Stellar Density

ABSTRACT New data from the Gaia satellite, when combined with accurate photometry from the Pan-STARRS survey, allow us to accurately estimate the properties of the GD-1 stream. Here, we analyse the stellar density variations in the GD-1 stream and show that they cannot be due to known baryonic structures such as giant molecular clouds, globular clusters, or the Milky Way’s bar or spiral arms. A joint analysis of the GD-1 and Pal 5 streams instead requires a population of dark substructures with masses ≈107–$10^9 \ \rm {M}_{\odot }$. We infer a total abundance of dark subhaloes normalized to standard cold dark matter $n_{\rm sub}/n_{\rm sub, CDM} = 0.4 ^{+0.3}_{-0.2}$ (68 per cent), which corresponds to a mass fraction contained in the subhaloes $f_{\rm {sub}} = 0.14 ^{+0.11}_{-0.07} {{\ \rm per\ cent}}$, compatible with the predictions of hydrodynamical simulation of cold dark matter with baryons.

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Formation of massive globular clusters with dark matter and its implication on dark matter annihilation

Monthly Notices of the Royal Astronomical Society Letters ◽

10.1093/mnrasl/slaa089 ◽

2020 ◽

Vol 496 (1) ◽

pp. L70-L74

Author(s):

Henriette Wirth ◽

Kenji Bekki ◽

Kohei Hayashi

Keyword(s):

Dark Matter ◽

Observational Studies ◽

Globular Clusters ◽

Galactic Halo ◽

Dwarf Galaxies ◽

Large Range ◽

Dark Matter Annihilation ◽

Central Regions ◽

Γ Ray ◽

The Masses

ABSTRACT Recent observational studies of γ-ray emission from massive globular clusters (GCs) have revealed possible evidence of dark matter (DM) annihilation within GCs. It is, however, still controversial whether the emission comes from DM or from millisecond pulsars. We here present the new results of numerical simulations, which demonstrate that GCs with DM can originate from nucleated dwarfs orbiting the ancient Milky Way. The simulated stripped nuclei (i.e. GCs) have the central DM densities ranging from 0.1 to several M⊙ pc−3, depending on the orbits and the masses of the host dwarf galaxies. However, GCs born outside the central regions of their hosts can have no/little DM after their hosts are destroyed and the GCs become the Galactic halo GCs. These results suggest that only GCs originating from stellar nuclei of dwarfs can possibly have DM. We further calculate the expected γ-ray emission from these simulated GCs and compare them to observations of ω Cen. Given the large range of DM densities in the simulated GCs, we suggest that the recent possible detection of DM annihilation from GCs should be more carefully interpreted.

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2dF Spectroscopy of Globular Clusters in M104

Highlights of Astronomy ◽

10.1017/s1539299600015653 ◽

2005 ◽

Vol 13 ◽

pp. 199-199

Author(s):

Terry Bridges ◽

Steve Zepf ◽

Katherine Rhode ◽

Ken Freeman

Keyword(s):

Dark Matter ◽

Strong Evidence ◽

Total Mass ◽

Globular Clusters ◽

Total Sample ◽

Dark Matter Halo ◽

Large Radius ◽

Counter Rotation ◽

Spatial Coverage

AbstractWe have found 56 new globular clusters in M104 from 2dF multi-fiber spectroscopy, doubling the number of confirmed clusters, and extending the spatial coverage to 50 kpc radius. We find no significant rotation in the total sample, or for subsets split by color or radius. However, there are hints that the blue clusters have a higher rotation than the red clusters, and for counter-rotation of clusters at large radius. We find a total mass of M ~ 1 × 1012M⊙ and a (M/L)B =30 out to 50 kpc radius, which is strong evidence for a dark matter halo in M104.

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Embedding globular clusters in dark matter minihaloes solves the cusp–core and timing problems in the Fornax dwarf galaxy

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/staa011 ◽

2020 ◽

Vol 492 (3) ◽

pp. 3169-3178 ◽

Cited By ~ 1

Author(s):

Pierre Boldrini ◽

Roya Mohayaee ◽

Joseph Silk

Keyword(s):

Dark Matter ◽

Globular Clusters ◽

Dwarf Galaxy ◽

Large Fraction ◽

Star Clusters ◽

Circumstantial Evidence ◽

Core Size ◽

Core Problem ◽

Good Agreement

ABSTRACT We use a fully GPU N-body code to demonstrate that dark matter (DM) minihaloes, as a new component of globular clusters (GCs), resolve both the timing and cusp–core problems in Fornax if the (five or six) GCs were recently accreted (≤3 Gyr ago) by Fornax. Under these assumptions, infall of these GCs does not occur and no star clusters form in the centre of Fornax in accordance with observations. We find that crossings of GCss that have DM minihaloes near the Fornax centre induce a cusp-to-core transition of the DM halo and hence resolve the cusp–core problem in this dwarf galaxy. The DM core size depends on the frequency of GC crossings. Our simulations clearly demonstrate also that between the passages, the DM halo can regenerate its cusp. Moreover, our models are in good agreement with constraints on the DM masses of GCs as our clusters lose a large fraction of their initial DM minihaloes. These results provide circumstantial evidence for the universal existence of DM haloes in GCs.

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Testing for Dark Matter in the Outskirts of Globular Clusters

The Astrophysical Journal ◽

10.3847/1538-4357/ac289f ◽

2021 ◽

Vol 922 (2) ◽

pp. 104

Author(s):

Raymond G. Carlberg ◽

Carl J. Grillmair

Keyword(s):

Dark Matter ◽

Globular Clusters ◽

High Probability ◽

Velocity Dispersion ◽

High Redshift ◽

Dark Matter Halo ◽

The Sun ◽

Proper Motions ◽

Preliminary Results ◽

Galactic Background

Abstract The proper motions of stars in the outskirts of globular clusters are used to estimate cluster velocity dispersion profiles as far as possible within their tidal radii. We use individual color–magnitude diagrams to select high-probability cluster stars for 25 metal-poor globular clusters within 20 kpc of the Sun, 19 of which have substantial numbers of stars at large radii. Of the 19, 11 clusters have a falling velocity dispersion in the 3–6 half-mass radii range, 6 are flat, and 2 plausibly have a rising velocity dispersion. The profiles are all in the range expected from simulated clusters that started at high redshift in a zoom-in cosmological simulation. The 11 clusters with falling velocity dispersion profiles are consistent with no dark matter above the Galactic background. The six clusters with approximately flat velocity dispersion profiles could have local dark matter, but are ambiguous. The two clusters with rising velocity dispersion profiles are consistent with a remnant local dark matter halo, but need membership confirmation and detailed orbital modeling to further test these preliminary results.

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The Mass Distribution In Clusters Of Galaxies From Weak And Strong Lensing

Symposium - International Astronomical Union ◽

10.1017/s0074180900231136 ◽

1996 ◽

Vol 173 ◽

pp. 131-136 ◽

Cited By ~ 1

Author(s):

Jordi Miralda-Escudé

Keyword(s):

Dark Matter ◽

Mass Distribution ◽

Inversion Formula ◽

Weak Lensing ◽

Clear Understanding ◽

Clusters Of Galaxies ◽

Matter Distribution ◽

Strong Lensing ◽

Similar Information ◽

Dark Matter Distribution

This paper is intended as an introduction to the theory of weak lensing. A review of the inversion formula introduced by Kaiser and Squires is presented. We then prove the formula of the aperture densitometry method in a simple way that allows a clear understanding of where the various terms come from. This is particularly useful to measure quantitatively masses in any region of a lens. We then summarize what has been learned from observations of strong lensing about the dark matter distribution; weak lensing should provide similar information on larger scales in clusters of galaxies.

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