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Excursion sets with a 'perfect' collapse model
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DOI：10.1093/mnras/staf1029.png)
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Abstract
En 中文
The Lambda cold dark matter model predicts structure formation across a vast mass range, from massive clusters (similar to 10(15) M-circle dot)to Earth-massmicro-haloes(similar to 10(-6) M-circle dot),, resolving which far exceeds the capabilities of current simulations. Excursion set models are the most efficient theoretical tool to disentangle this hierarchy in mass. We test the excursion set paradigm by combining smoothed initial density fields with a 'perfect' collapse model - N-body simulations. We find that a core excursion set assumption - small-scale perturbations do not impact larger scale collapse - is approximately fulfilled but exhibits small quantitative violations dependent on the smoothing filter. For a sharp k-space cut-off similar to 20 per cent of mass elements revert collapse as the smoothing scale decreases, while only 3.5 per cent do for a Gaussian and 5 percent for a top-hat. Further, we test the simple deterministic mass-mapping M x R-3 (first-crossing scale to halo mass) relation. We find that particles that are first accreted into haloes at the same smoothing scale may end up in haloes of significantly different masses, with a scatter of 0.4-0.8 dex. We also demonstrate that the proportionality constant of this relation should be considered as a degree of freedom. Finally, we measure the mass fraction in different structure morphologies (voids, pancakes, filaments, and haloes) as a function of filter scale. Typical particles appear to be part of a large-scale pancake, a smaller scale filament, and a notably smaller halo. We conclude that validating predictions of excursion set models on a particle-by-particle basis against simulations may enhance their realism.
Keywords:
methods: analytical
methods: numerical
galaxies: haloes
dark matter
large-scale structure of Universe
cosmology: theory
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