Deriving the Nonlinear Cosmological Power Spectrum and Bispectrum from Analytic Dark Matter Halo Profiles and Mass Functions

ABSTRACT We present a method for generating suites of dark matter halo catalogues with only a few N-body simulations, focusing on making small changes to the underlying cosmology of a simulation with high precision. In the context of blind challenges, this allows us to re-use a simulation by giving it a new cosmology after the original cosmology is revealed. Starting with full N-body realizations of an original cosmology and a target cosmology, we fit a transfer function that displaces haloes in the original so that the galaxy/HOD power spectrum matches that of the target cosmology. This measured transfer function can then be applied to a new realization of the original cosmology to create a new realization of the target cosmology. For a 1 per cent change in σ8, we achieve 0.1 per cent accuracy to $k = 1\, h\, \mathrm{Mpc}^{-1}$ in the real-space power spectrum; this degrades to 0.3 per cent when the transfer function is applied to a new realization. We achieve similar accuracy in the redshift-space monopole and quadrupole. In all cases, the result is better than the sample variance of our $1.1\, h^{-1}\, \mathrm{Gpc}$ simulation boxes.

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Formation and Evolution of Disk Galaxies

Symposium - International Astronomical Union ◽

10.1017/s0074180900132334 ◽

1999 ◽

Vol 183 ◽

pp. 153-153

Author(s):

C. Firmani ◽

V. Avila-Reese

Keyword(s):

Dark Matter ◽

Angular Momentum ◽

Power Spectrum ◽

Mass Velocity ◽

Dark Matter Halo ◽

Stellar Disk ◽

Physical Factors ◽

Disk Galaxies ◽

Velocity Relation ◽

Formation And Evolution

We have developed a semianalitical approach to study galaxy formation and evolution in the cosmological context. Disk galaxies (dark matter halo+luminous disk) are considered to be formed through an extended process of gravitational collapse, whose character is determined by the statistical properties of the density fluctuation field assumed here to be Gaussian. Gas disks in centrifugal equilibrium within the collapsing dark halos are built up (detailed angular momentum conservation is assumed), and their galactic evolution is calculated with a model which consider all the gravitational interactions, the hydrodynamics of the ISM, and the SF process. A bulge as product of stellar disk gravitational instabilities is constructed. To study general behaviors a Gaussian σ8 = 1 SCDM model is used. For a given mass one obtains a range of dark matter configurations. The average case is in excellent agreement with results of cosmological N-body simulations. The slope of the mass-velocity relation agrees with the slope of the H- and I-band Tully-Fisher relations, but the velocities are too high. This problem dissapears if the power spectrum is renormalized to σ8 = 0.57, suggesting that the TF relation is result of the natural extension to galactic scales of the galaxy distribution power spectrum, and that on the basis of its origin are the cosmological initial conditions. The scatter on the mass-velocity relation is realistic. The models predict disk exponential surface brightness (SB) profiles, nearly flat rotation curves, and negative radial gradients in the B-V color. The obtained, gas fractions, B-V colors, central SBs μB0, bulge-to-disk (b/d) ratios, and rotation velocities (for σ8 = 0.57) are in agreement with observations, and their correlations are similar to those which define the Hubble sequence, including the LSB galaxies. These properties and correlations are the product of the combination of three fundamental physical factors: the mass, the mass aggregation history (MAH), and the initial angular momentum. The intensive properties are almost invariant to the mass, the MAH determines the B-V color, and the spin parameter λ mainly influences on μB0, and b/d ratio.

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Dependence on the environment of the abundance function of light-cone simulation dark matter haloes

Astronomy and Astrophysics ◽

10.1051/0004-6361/201731440 ◽

2018 ◽

Vol 616 ◽

pp. A137 ◽

Cited By ~ 2

Author(s):

Maria Chira ◽

Manolis Plionis ◽

Pier-Stefano Corasaniti

Keyword(s):

Dark Matter ◽

Power Law ◽

Phenomenological Model ◽

Light Cone ◽

Dark Matter Halo ◽

Nearest Neighbour ◽

Spherical Region ◽

Theoretical Mass ◽

Mass Functions ◽

Characteristic Mass

Aims. We study the dependence of the halo abundance function (AF) on different environments in a whole-sky ΛCDM light-cone halo catalogue extending to z ~ 0.65, using a simple and well-defined halo isolation criterion. Methods. The isolation status of each individual dark matter halo is determined by the distance to its nearest neighbour, which defines the maximum spherical region devoid of halos above a threshold mass around it (although the true size of such region may be much larger since it is not necessarily spherical). A versatile double power-law Schechter function is used to fit the dark matter halo AF, and its derived parameters are studied as a function of halo isolation status. Results. (a) Our function fits the halo abundances for all halo isolation statuses extremely well, while the well-established theoretical mass functions, integrated over the volume of the light-cone, provide an adequate but poorer fit than our phenomenological model. (b) As expected, and in agreement with other studies based on snap-shot simulations, we find significant differences of the halo abundance function as a function of halo isolation, indicating different rates of halo formation. The slope of the power law and the characteristic mass of the Schechter-like fitting function decrease with isolation, a result consistent with the formation of less massive haloes in lower density regions. (c) We find an unexpected upturn of the characteristic mass of the most isolated haloes of our sample. This upturn originates and characterises only the higher redshift regime (z ≳ 0.45), which probably implies a significant and recent evolution of the isolation status of the most isolated and most massive haloes.

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Modified initial power spectrum and too big to fail problem

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/staa1058 ◽

2020 ◽

Vol 494 (4) ◽

pp. 4907-4913 ◽

Cited By ~ 1

Author(s):

Hamed Kameli ◽

Shant Baghram

Keyword(s):

Dark Matter ◽

Standard Model ◽

Power Spectrum ◽

Initial Conditions ◽

Dark Matter Halo ◽

Current Status ◽

Number Density ◽

Too Big To Fail ◽

Standard Case ◽

Initial Power

ABSTRACT The galactic scale challenges of dark matter such as ‘missing satellite’ problem and ‘too big to fail’ problem are the main caveats of standard model of cosmology. These challenges could be solved either by implementing the complicated baryonic physics or it could be considered as an indication to a new physics beyond the standard model of cosmology. The modification of collisionless dark matter models or the standard initial conditions are two promising venues for study. In this work, we investigate the effects of the deviations from scale invariant initial curvature power spectrum on number density of dark matter haloes. We develop the non-Markov extension of the excursion set theory to calculate the number density of dark matter substructures and dark matter halo progenitor mass distribution. We show that the plausible solution to ‘too big to fail’ problem could be obtained by a Gaussian excess in initial power in the scales of k* ∼ 3 h Mpc−1 that is related to the mass scale of M* ∼ 1011 M⊙. We show that this deviation leads to the decrement of dark matter subhaloes in galactic scale, which is consistent with the current status of the non-linear power spectrum. Our proposal also has a prediction that the number density of Milky Way-type galaxies must be higher than the standard case.

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The stellar-to-halo mass relation over the past 12 Gyr

Astronomy and Astrophysics ◽

10.1051/0004-6361/201936329 ◽

2020 ◽

Vol 634 ◽

pp. A135 ◽

Cited By ~ 6

Author(s):

G. Girelli ◽

L. Pozzetti ◽

M. Bolzonella ◽

C. Giocoli ◽

F. Marulli ◽

...

Keyword(s):

Dark Matter ◽

Star Formation ◽

Galaxy Formation ◽

Stellar Mass ◽

Dark Matter Halo ◽

Mass Relation ◽

Massive Galaxies ◽

Halo Masses ◽

Formation Efficiency ◽

Mass Functions

Aims. Understanding the link between the galaxy properties and the dark matter halos they reside in and their coevolution is a powerful tool for constraining the processes related to galaxy formation. In particular, the stellar-to-halo mass relation (SHMR) and its evolution throughout the history of the Universe provides insights on galaxy formation models and allows us to assign galaxy masses to halos in N-body dark matter simulations. To address these questions, we determine the SHMR throughout the entire cosmic history from z ∼ 4 to the present. Methods. We used a statistical approach to link the observed galaxy stellar mass functions on the COSMOS field to dark matter halo mass functions up to z ∼ 4 from the ΛCDM DUSTGRAIN-pathfinder simulation, which is complete for Mh > 1012.5 M⊙, and extended this to lower masses with a theoretical parameterization. We propose an empirical model to describe the evolution of the SHMR as a function of redshift (either in the presence or absence of a scatter in stellar mass at fixed halo mass), and compare the results with several literature works and semianalytic models of galaxy formation. We also tested the reliability of our results by comparing them to observed galaxy stellar mass functions and to clustering measurements. Results. We derive the SHMR from z = 0 to z = 4, and model its empirical evolution with redshift. We find that M*/Mh is always lower than ∼0.05 and depends both on redshift and halo mass, with a bell shape that peaks at Mh ∼ 1012 M⊙. Assuming a constant cosmic baryon fraction, we calculate the star-formation efficiency of galaxies and find that it is generally low; its peak increases with cosmic time from ∼30% at z ∼ 4 to ∼35% at z ∼ 0. Moreover, the star formation efficiency increases for increasing redshifts at masses higher than the peak of the SHMR, while the trend is reversed for masses lower than the peak. This indicates that massive galaxies (i.e., galaxies hosted at halo masses higher than the SHMR peak) formed with a higher efficiency at higher redshifts (i.e., downsizing effect) and vice versa for low-mass halos. We find a large scatter in results from semianalytic models, with a difference of up to a factor ∼8 compared to our results, and an opposite evolutionary trend at high halo masses. By comparing our results with those in the literature, we find that while at z ∼ 0 all results agree well (within a factor of ∼3), at z > 0 many differences emerge. This suggests that observational and theoretical work still needs to be done. Our results agree well (within ∼10%) with observed stellar mass functions (out to z = 4) and observed clustering of massive galaxies (M* > 1011 M⊙ from z ∼ 0.5 to z ∼ 1.1) in the two-halo regime.

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The normalization and slope of the dark matter (sub-)halo mass function on sub-galactic scales

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/staa341 ◽

2020 ◽

Vol 493 (1) ◽

pp. 1268-1276

Author(s):

Andrew J Benson

Keyword(s):

Dark Matter ◽

Gravitational Lensing ◽

Cold Dark Matter ◽

Mass Range ◽

Mass Function ◽

Matter Content ◽

Dark Matter Halo ◽

Halo Masses ◽

Near Future ◽

Mass Functions

ABSTRACT Simulations of cold dark matter make robust predictions about the slope and normalization of the dark matter halo and subhalo mass functions on small scales. Recent observational advances utilizing strong gravitational lensing have demonstrated the ability of this technique to place constraints on these quantities on subgalactic scales corresponding to dark matter halo masses of 106–$10^9\, \mathrm{M}_\odot$. On these scales the physics of baryons, which make up around 17 per cent of the matter content of the Universe but which are not included in pure dark matter N-body simulations, are expected to affect the growth of structure and the collapse of dark matter haloes. In this work, we develop a semi-analytic model to predict the amplitude and slope of the dark matter halo and subhalo mass functions on subgalactic scales in the presence of baryons. We find that the halo mass function is suppressed by up to 25 per cent, and the slope is modified, ranging from −1.916 to −1.868 in this mass range. These results are consistent with current measurements, but differ sufficiently from the expectations for a dark matter only universe that it may be testable in the near future.

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Testing dark matter halo properties using self-similarity

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/staa3435 ◽

2020 ◽

Author(s):

M Leroy ◽

L Garrison ◽

D Eisenstein ◽

M Joyce ◽

S Maleubre

Keyword(s):

Dark Matter ◽

Particle Number ◽

Percent Level ◽

Mass Function ◽

Dark Matter Halo ◽

Self Similarity ◽

Good Convergence ◽

Scale Free ◽

Point Correlation ◽

Mass Functions

Abstract We use self-similarity in N-body simulations of scale-free models to test for resolution dependence in the mass function and two-point correlation functions of dark matter halos. We use 10243 particle simulations performed with Abacus, and compare results obtained with two halo finders: friends-of-friends (fof) and Rockstar. The fof mass functions show a systematic deviation from self-similarity which is explained by resolution dependence of the fof mass assignment previously reported in the literature. Weak evidence for convergence is observed only starting from halos of several thousand particles, and mass functions are overestimated by at least as much as $20-25\%$ for halos of 50 particles. The mass function of the default Rockstar halo catalog (with bound virial spherical overdensity mass), on the other hand, shows good convergence from of order 50 to 100 particles per halo, with no detectable evidence at the few percent level of any systematic dependence for larger particle number. Tests show that the mass unbinding procedure in Rockstar is the key factor in obtaining this much improved resolution. Applying the same analysis to the halo-halo two point correlation function, we find again strong evidence for convergence only for Rockstar halos, at separations sufficiently large so that halos do not overlap. At these separations we can exclude dependence on resolution at the $5-10\%$ level once halos have of order 50 to 100 particles. At smaller separations results are not converged even at significantly larger particle number, and bigger simulations would be required to establish the resolution required for convergence.

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