The spin and shape of dark matter haloes in the Millennium simulation of a Λ cold dark matter universe

By P. Bett, V. Eke, Carlos S. Frenk, Adrian Jenkins, John C. Helly, J. N. Icc, U. Durham, D. Physics, Astronomy, U. Victoria. 2006

406 citations recorded by the source corpus.

We investigate the spins and shapes of over a million dark matter haloes identified at z = 0 in the Millennium simulation. Our sample spans halo masses ranging from dwarf galaxies to rich galaxy clusters. The very large dynamic range of this A cold dark matter cosmological simulation enables the distribution of spins and shapes and their variation with halo mass and environment to be characterized with unprecedented precision. We compare results for haloes identified using three different algorithms, and investigate (and remove) biases in the estimate of angular momentum introduced both by the algorithm itself and by numerical effects. We introduce a novel halo definition called the TREE halo, based on the branches of the halo merger trees, which is more appropriate for comparison with real astronomical objects than the traditional 'friends-of-friends' and 'spherical overdensity' (SO) algorithms. We find that for this many objects, the traditional lognormal function is no longer an adequate description of the distribution, P(λ), of the dimensionless spin parameter λ, and we provide a different function that gives a better fit for TREE and SO haloes. The variation in spin with halo mass is weak but detectable, although the trend depends strongly on the halo definition used. For the entire population of haloes, we find median values of λ med = 0.0367-0.0429, depending on the definition of a halo. The haloes exhibit a range of shapes, with a preference for prolateness over oblateness. More-massive haloes tend to be less spherical and more prolate. We find that the more-spherical haloes have less coherent rotation in the median, and those closest to being spherical have a spin independent of mass (λ med ≈0.033). The most-massive haloes have a spin independent of shape (λ med ≈0.032). The majority of haloes have their angular momentum vector aligned with their minor axis and perpendicular to their major axis. We find a general trend for higher spin haloes to be more clustered, with a stronger effect for more-massive haloes. For galaxy cluster haloes, this can be larger than a factor of∼2.

Subfields: Astronomy and Astrophysics, Instrumentation

View Paper: https://www.semanticscholar.org/paper/2841bb28a48d8f33b8401aba92b9b87af77efdad

How researchers see this paper

The researchers whose trusted networks rank it highest, strongest advocate first. Every researcher gets a different order.

In Astronomy and Astrophysics

1. P. Hopkins
2. L. Hernquist
3. Volker Springel
4. Simon D. M. White
5. A. Dekel
6. R. Dav'e
7. R. Somerville
8. T. Naab

In Instrumentation

1. P. Hopkins
2. L. Hernquist
3. Volker Springel
4. Simon D. M. White
5. A. Dekel
6. A. Benson
7. R. Dav'e
8. R. Somerville

Citations in the corpus

• Galaxy Alignments: An Overview (2015, background): “It should be noted that the simulation suites used in that work contained a total of 103 to 104 particles, with massive clusters typically consisting of 10 − 30 particles, which is at least an order of magnitude below current limits for reliable measurements of halo shapes and angular momenta (Bett ”
• Halo and subhalo demographics with Planck cosmological parameters: Bolshoi–Planck and MultiDark–Planck simulations (2016, methodology): “Halo Demographics with Planck Parameters 17 is consistent with previous findings based on high resolution N−body simulations (e.g., Bett et al. 2007).”
• Galaxy formation theory (2010, background): “…1987; Efstathiou et al. 1988; Warren et al. 1992; Cole and Lacey 1996; Lemson and Kauffmann 1999; Bullock et al. 2001a; van den Bosch et al. 2002; Bett et al. 2007; Gao et al. 2008) and internal structure (Moore et al. 1999; Klypin et al. 1999; Kuhlen et al. 2008; Springel et al. 2008) of dark…”
• Galaxy-induced transformation of dark matter haloes (2009, background): “…systems supported by anisotropic velocity dispersion tensors (Frenk et al., 1988; Jing & Suto, 2002; Allgood et al., 2006; Hayashi et al., 2007; Bett et al., 2007), a result that reflects the highly aspherical nature of gravitationally-amplified density fluctuations as they become non linear…”
• Misaligned angular momentum in hydrodynamic cosmological simulations: warps, outer discs and thick discs (2010, background): “Note that this is not the moment of inertia tensor, although in the literature this nomenclature is often used (see Bett et al. 2007).”
• SUBSTRUCTURE DEPLETION IN THE MILKY WAY HALO BY THE DISK (2009, background): “The halo spin parameter is 0.04 at z = 0, close to the average value≈ 0.035 for halos in large cosmological simulations (Bett et al. 2007).”
• Galacticus: A Semi-Analytic Model of Galaxy Formation (2010, methodology): “Bett2007: Under this method the spin is drawn from the distribution found by Bett et al. (2007).”
• Resolving cosmic structure formation with the Millennium-II simulation (2009, background): “…time, including concentration, substructure content, and spin (e.g., Harker et al. 2006; Wechsler et al. 2006; Wetzel et al. 2007; Jing et al. 2007; Bett et al. 2007; Gao & White 2007; Dalal et al. 2008; Angulo et al. 2008) With the MS-II, we are able to investigate assembly bias at much lower…”
• From Rings to Bulges: Evidence for Rapid Secular Galaxy Evolution at z ~ 2 from Integral Field Spectroscopy in the SINS Survey (2008, background): “…the halo (e.g., Mo et al. 1998), the radius of the initial starforming disk is set by the characteristic angular momentum parameter kh (hkhi 0:04; Bett et al. 2007) of the accreting gas, Rd khRvir/ ffiffiffi 2 p , where Rvir ( 100Y150 kpc; Förster Schreiber et al. 2006) is the virial radius of…”
• The mass–concentration–redshift relation of cold and warm dark matter haloes (2016, background): “…al. 2007), or the mass-fraction in substructure (e.g. Neto et al. 2007; Ludlow et al. 2012); others, such as the virial ratio, η = 2 K/|U| (e.g. Cole & Lacey 1996; Bett et al. 2007; Knebe & Power 2008), or spin parameter, λ (e.g. Klypin et al. 2016), gauge the internal dynamical state of the halo.”
• ON THE ACCURACY OF WEAK-LENSING CLUSTER MASS RECONSTRUCTIONS (2010, methodology): “We also do not apply radial weighting and do not remove subhalos, as is often done in more sophisticated algorithms measuring halo triaxiality (e.g., Bett et al. 2007; Lau et al. 2011).”
• Halo Assembly Bias in Hierarchical Structure Formation (2008, positive): “…environment of a halo refers to the density, smoothed on some suitably large scale, e.g. 8 h−1Mpc. Wechsler et al. 2006; Harker et al. 2006; Bett et al. 2007; Wetzel et al. 2007; Jing, Suto & Mo 2007; Gao & White 2007; Angulo, Baugh & Lacey 2008) Using a marked correlation function, Sheth…”
• FORMATION OF THE FIRST NUCLEAR CLUSTERS AND MASSIVE BLACK HOLES AT HIGH REDSHIFT (2008, methodology): “To each halo we assign a value of the spin parameter, λ, extracted from the probability distribution found in the Millennium simulations (Bett et al. 2007): P (log λ) = A ( λ λ0 )3 exp [ −ζ ( λ λ0 )3/ζ ] , (16) where λ0 = 0.0043 is the peak location, ζ = 2.509 and the normalization reads A = 3 ln…”
• THE SPIN AND ORIENTATION OF DARK MATTER HALOS WITHIN COSMIC FILAMENTS (2009, background): “In addition to the age, other halo properties such as concentration and spin have also been found to correlate with the local environment (Avila-Reese et al. 2005; Wechsler et al. 2005; Bett et al. 2007; Gao & White 2007; Macciò et al. 2007).”
• A unified multiwavelength model of galaxy formation (2015, background): “…then loses its thermal energy by radiative cooling due to atomic processes, at ar te 5 These values are also very close to the best-fit lognormal parmeters from Bett et al. (2007) per unit volumeρ2hotΛ(Tvir, Zhot) (assuming collisional ionization equilibrium), whereZhot is metallicity of this gas.”