Redefining the Missing Satellites Problem

Strigari, Louis E.; Bullock, James S.; Kaplinghat, Manoj; Diemand, Juerg; Kuhlen, M.; Madau, Piero

doi:10.1086/521914

Cited by 222 publications

(313 citation statements)

References 52 publications

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“…These satellites are expected to be hosted by the largest subhalos in the MW halo, as they have the largest velocity dispersions observed from their rotation curves. However, the most massive subhalos predicted by CCDM-only simulations are too massive, with central densities too large, to host the brightest observed satellites [2,3,58]. Simulations predict O(10) subhalos with maximum circular velocity V max > 30 km/s, whereas the MW dSphs have V max < 25 km/s.…”

Section: Self-interacting Dark Matter and Small Scale Structurementioning

confidence: 92%

Beyond collisionless dark matter: Particle physics dynamics for dark matter halo structure

2013

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Dark matter (DM) self-interactions have important implications for the formation and evolution of structure, from dwarf galaxies to clusters of galaxies. We study the dynamics of self-interacting DM via a light mediator, focusing on the quantum resonant regime where the scattering cross section has a non-trivial velocity dependence. While there are long-standing indications that observations of small scale structure in the Universe are not in accord with the predictions of collisionless DM, theoretical study and simulations of DM self-interactions have focused on parameter regimes with simple analytic solutions for the scattering cross section, with constant or classical velocity (and no angular) dependence. We devise a method that allows us to explore the velocity and angular dependence of self-scattering more broadly, in the strongly-coupled resonant and classical regimes where many partial modes are necessary for the achieving the result. We map out the entire parameter space of DM self-interactions -and implications for structure observations -as a function of the coupling and the DM and mediator masses. We derive a new analytic formula for describing resonant s-wave scattering. Finally, we show that DM self-interactions can be correlated with observations of Sommerfeld enhancements in DM annihilation through indirect detection experiments.

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Section: Self-interacting Dark Matter and Small Scale Structurementioning

confidence: 92%

Beyond collisionless dark matter: Particle physics dynamics for dark matter halo structure

2013

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“…The symbols represent the virial mass estimates obtained at different radii in previous studies by (Strigari et al 2007;Strigari et al 2008;Walker & Peñarrubia 2011;Amorisco & Evans 2011) 3 . Most of the virial mass estimates are consistent with our mass profiles, and do not distinguish between a cored or a cusped DM profile, except for Walker & Peñarrubia (2011).…”

Section: The Mass Profilesmentioning

confidence: 99%

A discrete chemo-dynamical model of the dwarf spheroidal galaxy Sculptor: mass profile, velocity anisotropy and internal rotation

Zhu

Ven

Watkins³

et al. 2016

Mon. Not. R. Astron. Soc.

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We present a new discrete chemo-dynamical axisymmetric modeling technique, which we apply to the dwarf spheroidal galaxy Sculptor. The major improvement over previous Jeans models is that realistic chemical distributions are included directly in the dynamical modelling of the discrete data. This avoids loss of information due to spatial binning and eliminates the need for hard cuts to remove contaminants and to separate stars based on their chemical properties. Using a combined likelihood in position, metallicity and kinematics, we find that our models naturally separate Sculptor stars into a metal-rich and a metal-poor population. Allowing for non-spherical symmetry, our approach provides a central slope of the dark matter density of γ = 0.5 ± 0.3. The metal-rich population is nearly isotropic (with β red r = 0.0 ± 0.1) while the metal-poor population is tangentially anisotropic (with β blue r = −0.2 ± 0.1) around the half light radius of 0.26 kpc. A weak internal rotation of the metal-rich population is revealed with v max /σ 0 = 0.15 ± 0.15. We run tests using mock data to show that a discrete dataset with ∼ 6000 stars is required to distinguish between a core (γ = 0) and cusp (γ = 1), and to constrain the possible internal rotation to better than 1 σ confidence with our model. We conclude that our discrete chemo-dynamical modelling technique provides a flexible and powerful tool to robustly constrain the internal dynamics of multiple populations, and the total mass distribution in a stellar system.

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“…There are several proposed scenarios to solve this issue, like reducing the number of expected satellites as only the most massive progenitors (Libeskind et al 2005), the earliest formed haloes (Strigari et al 2007) or even only the lowmass systems (Sales et al 2007) are to be expected to produce satellite galaxies surviving until today. Other possibilities are to assume that only the most massive subhaloes were able to form stars (Stoehr et al 2002).…”

Section: Introductionmentioning

confidence: 99%

Making counter-orbiting tidal debris

Pawlowski

Kroupa

Boer

2011

A&A

107

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Using stellar-dynamical calculations it is shown for the first time that counter-orbiting material emerges naturally in tidal interactions of disc galaxies. Model particles on both pro-and retrograde orbits can be formed as tidal debris in single encounters with disc galaxies of 1-to-1 and 4-to-1 mass ratios. A total of 74 model calculations are performed for a range of different initial parameters. Interactions include fly-by and merger cases. The fraction of counter-orbiting material produced varies over a wide range (from a few up to 50 percent). All fly-by models show a similar two-phase behaviour, with retrograde material forming first. Properties of the prograde and retrograde populations are extracted to make an observational discrimination possible. During such encounters the tidal debris occupies a certain region in phase space. In this material, tidal-dwarf galaxies may form. The modelling therefore can explain why galaxies may have dwarf galaxies orbiting counter to the bulk of their dwarf galaxies. An example is the Sculptor dwarf of the Milky Way, which orbits counter to the bulk of the disc of satellites. The modelling thus supports the scenario of the MW satellites being ancient tidal-dwarf galaxies formed from gaseous material stripped from another galaxy during an encounter with the young MW. A possible candidate for this galaxy is identified as the Magellanic Cloud progenitor galaxy. Its angular motion fits the angular motion of the MW disc of satellites objects. This scenario is in agreement with Lynden-Bell's original suggestion for the origin of the dSph satellites and the near-unbound orbit of the LMC.

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Redefining the Missing Satellites Problem

Cited by 222 publications

References 52 publications

Beyond collisionless dark matter: Particle physics dynamics for dark matter halo structure

Beyond collisionless dark matter: Particle physics dynamics for dark matter halo structure

A discrete chemo-dynamical model of the dwarf spheroidal galaxy Sculptor: mass profile, velocity anisotropy and internal rotation

Making counter-orbiting tidal debris

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