Dissecting the spin distribution of dark matter haloes

Antonuccio-Delogu, V.; Dobrotka, A.; Cielo, Salvatore; Giocoli, Carlo; Macciò, Andrea V.; Romeo-Veloná, A.

doi:10.1111/j.1365-2966.2010.16989.x

Cited by 16 publications

(18 citation statements)

References 64 publications

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“…We can see that there are small deviations from the log-normal distributions at high spin regions as seen in previous works for larger halos Antonuccio-Delogu et al 2010). We will discuss the effect of the dynamical state of halos in the Appendix.…”

Section: Spin Distributionssupporting

confidence: 83%

The Cosmogrid Simulation: Statistical Properties of Small Dark Matter Halos

Ishiyama

Rieder

Makino

et al. 2013

ApJ

100

104

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We present the results of the "Cosmogrid" cosmological N-body simulation suites based on the concordance LCDM model. The Cosmogrid simulation was performed in a 30 Mpc box with 2048 3 particles. The mass of each particle is 1.28 × 10 5 M , which is sufficient to resolve ultra-faint dwarfs. We found that the halo mass function shows good agreement with the Sheth & Tormen fitting function down to ∼10 7 M . We have analyzed the spherically averaged density profiles of the three most massive halos which are of galaxy group size and contain at least 170 million particles. The slopes of these density profiles become shallower than −1 at the innermost radius. We also find a clear correlation of halo concentration with mass. The mass dependence of the concentration parameter cannot be expressed by a single power law, however a simple model based on the Press-Schechter theory proposed by Navarro et al. gives reasonable agreement with this dependence. The spin parameter does not show a correlation with the halo mass. The probability distribution functions for both concentration and spin are well fitted by the log-normal distribution for halos with the masses larger than ∼10 8 M . The subhalo abundance depends on the halo mass. Galaxy-sized halos have 50% more subhalos than ∼10 11 M halos have.

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Section: Spin Distributionssupporting

confidence: 83%

The Cosmogrid Simulation: Statistical Properties of Small Dark Matter Halos

Ishiyama

Rieder

Makino

et al. 2013

ApJ

100

104

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“…Cosmological N ‐body simulations of the standard CDM universe show that haloes form with a net angular momentum such that the dimensionless ratio which expresses their degree of rotational support, has typical values in the range [0.01, 0.1] with median value ≃ 0.05. These values can be found in Barnes & Efstathiou (1987), and more recently in Antonucci et al (2010), which seem to be confirmed by observations (see Hernandez et al 2007). In the above expression, L is the total angular momentum, E is the total energy and M is the total mass of the halo.…”

Section: Introductionsupporting

confidence: 83%

Angular momentum and vortex formation in Bose-Einstein-condensed cold dark matter haloes

Rindler-Daller¹,

Shapiro²

2012

Monthly Notices of the Royal Astronomical Society

182

199

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Various extensions of the standard model of particle physics predict the existence of very light bosons, with masses ranging from about 10 −5 eV for the QCD axion down to 10 −33 eV for ultra-light particles. These particles could be responsible for all or part of the cold dark matter (CDM) in the Universe. For such particles to serve as CDM, their phase-space density must be high enough to form a Bose-Einstein condensate (BEC). The fluid-like nature of BEC-CDM dynamics differs from that of standard collisionless CDM, however, so different signature effects on galactic haloes may allow observations to distinguish them. Standard CDM has problems with galaxy observations on small scales; cuspy central density profiles of haloes and the overabundance of subhaloes seem to conflict with observations of dwarf galaxies. It has been suggested that BEC-CDM can overcome these shortcomings for a large range of particle mass m and self-interaction coupling strength g. For quantum coherence to influence structure on the scale of galactic haloes of radius R and mass M, either the de-Broglie wavelength λ deB R, which requires m m H ∼ = 10 −25 (R/100 kpc) −1/2 (M/10 12 M ) −1/2 eV, or else λ deB R but gravity is balanced by self-interaction, which requires m m H and g g H ∼ = 2 × 10 −64 (R/100 kpc)(M/10 12 M ) −1 eV cm 3 . Here we study the largely neglected effects of angular momentum on BEC haloes. Dimensionless spin parameters λ 0.05 are expected from tidal-torquing by large-scale structure formation, just as for standard CDM. Since laboratory BECs develop quantum vortices if rotated rapidly enough, we ask whether this amount of angular momentum is sufficient to form vortices in BEC haloes, which would affect their structure with potentially observable consequences. The minimum angular momentum required for a halo to sustain a vortex, L QM , corresponds to per particle, or M/m. For λ = 0.05, this requires m ≥ 9.5m H , close enough to the particle mass required to influence structure on galactic scales that BEC haloes may be subject to vortex formation. While this is a necessary condition, it is not sufficient. To determine if and when quantum vortices will form in BEC haloes with a given λ-value, we study the equilibrium of self-gravitating, rotating, virialized BEC haloes which satisfy the Gross-Pitaevskii-Poisson equations, and calculate under what conditions vortices are energetically favoured, in two limits: either just enough angular momentum for one vortex or a significant excess of angular momentum. For λ = 0.05, vortex formation is energetically favoured for L/L QM ≥ 1 as long as both m/m H ≥ 9.5 and g/g H ≥ 68.0. Hence, vortices are expected for a wide range of BEC parameters. However, vortices cannot form for vanishing self-interaction (i.e. when λ deB R), and a range of particle parameters also remain even for BEC haloes supported by self-interaction, for which vortices will not form. Such BEC haloes can be modelled by compressible, (n = 1)-polytropic, irrotational Riemann-S ellipsoids.

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“…More massive halos tend to have lower λ c , which means that lower spin values are preferred in more massive halo samples. This is consistent with recent findings for massdependent spin distributions (Antonuccio-Delogu et al 2010;Knebe & Power 2008;Bett et al 2007). Figure 8 demonstrates how the characteristic spin (λ c ) has varied with the infall mass ratio (∆ log 10 M ) in recent epochs (0 ≤ z < 0.2).…”

Section: Asymptotic Walk Of Halo Spinsupporting

confidence: 94%

Stochastic Model of the Spin Distribution of Dark Matter Halos

Kim

Choi

Kim

et al. 2015

ApJS

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We employ a stochastic approach to probing the origin of the log-normal distributions of halo spin in N-body simulations. After analyzing spin evolution in halo merging trees, it was found that a spin change can be characterized by a stochastic random walk of angular momentum. Also, spin distributions generated by random walks are fairly consistent with those directly obtained from Nbody simulations. We derived a stochastic differential equation from a widely used spin definition and measured the probability distributions of the derived angular momentum change from a massive set of halo merging trees. The roles of major merging and accretion are also statistically analyzed in evolving spin distributions. Several factors (local environment, halo mass, merging mass ratio, and redshift) are found to influence the angular momentum change. The spin distributions generated in the mean-field or void regions tend to shift slightly to a higher spin value compared with simulated spin distributions, which seems to be caused by the correlated random walks. We verified the assumption of randomness in the angular momentum change observed in the N-body simulation and detected several degrees of correlation between walks, which may provide a clue for the discrepancies between the simulated and generated spin distributions in the voids. However, the generated spin distributions in the group and cluster regions successfully match the simulated spin distribution. We also demonstrated that the log-normality of the spin distribution is a natural consequence of the stochastic differential equation of the halo spin, which is well described by the Geometric Brownian Motion model. Subject headings: cosmology: theory -halo spin -large-scale structure of universe -methods: numerical -methods: statistical -random walk

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Dissecting the spin distribution of dark matter haloes

Cited by 16 publications

References 64 publications

The Cosmogrid Simulation: Statistical Properties of Small Dark Matter Halos

The Cosmogrid Simulation: Statistical Properties of Small Dark Matter Halos

Angular momentum and vortex formation in Bose-Einstein-condensed cold dark matter haloes

Stochastic Model of the Spin Distribution of Dark Matter Halos

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