Haloes gone MAD: The Halo-Finder Comparison Project Knebe, Alexander; Knollmann, Steffen R.; Muldrew, Stuart I. ...
Monthly notices of the Royal Astronomical Society,
08/2011, Letnik:
415, Številka:
3
Journal Article
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ABSTRACT
We present a detailed comparison of fundamental dark matter halo properties retrieved by a substantial number of different halo finders. These codes span a wide range of techniques including ...friends‐of‐friends, spherical‐overdensity and phase‐space‐based algorithms. We further introduce a robust (and publicly available) suite of test scenarios that allow halo finder developers to compare the performance of their codes against those presented here. This set includes mock haloes containing various levels and distributions of substructure at a range of resolutions as well as a cosmological simulation of the large‐scale structure of the universe.
All the halo‐finding codes tested could successfully recover the spatial location of our mock haloes. They further returned lists of particles (potentially) belonging to the object that led to coinciding values for the maximum of the circular velocity profile and the radius where it is reached. All the finders based in configuration space struggled to recover substructure that was located close to the centre of the host halo, and the radial dependence of the mass recovered varies from finder to finder. Those finders based in phase space could resolve central substructure although they found difficulties in accurately recovering its properties. Through a resolution study we found that most of the finders could not reliably recover substructure containing fewer than 30–40 particles. However, also here the phase‐space finders excelled by resolving substructure down to 10–20 particles. By comparing the halo finders using a high‐resolution cosmological volume, we found that they agree remarkably well on fundamental properties of astrophysical significance (e.g. mass, position, velocity and peak of the rotation curve).
We further suggest to utilize the peak of the rotation curve, vmax, as a proxy for mass, given the arbitrariness in defining a proper halo edge.
We present a comparison of major methodologies of fast generating mock halo or galaxy catalogues. The comparison is done for two-point (power spectrum and two-point correlation function in real and ...redshift space), and the three-point clustering statistics (bispectrum and three-point correlation function). The reference catalogues are drawn from the BigMultiDark N-body simulation. Both friend-of-friends (including distinct haloes only) and spherical overdensity (including distinct haloes and subhalos) catalogues have been used with the typical number density of a large volume galaxy surveys. We demonstrate that a proper biasing model is essential for reproducing the power spectrum at quasi-linear and even smaller scales. With respect to various clustering statistics, a methodology based on perturbation theory and a realistic biasing model leads to very good agreement with N-body simulations. However, for the quadrupole of the correlation function or the power spectrum, only the method based on semi-N-body simulation could reach high accuracy (1 per cent level) at small scales, i.e. r < 25 h
−1 Mpc or k > 0.15 h Mpc−1. Full N-body solutions will remain indispensable to produce reference catalogues. Nevertheless, we have demonstrated that the more efficient approximate solvers can reach a few per cent accuracy in terms of clustering statistics at the scales interesting for the large-scale structure analysis. This makes them useful for massive production aimed at covariance studies, to scan large parameter spaces, and to estimate uncertainties in data analysis techniques, such as baryon acoustic oscillation reconstruction, redshift distortion measurements, etc.
Several ‘great walls’ are clearly visible in the Durham/UKST Galaxy Redshift Survey (DURS). We make a statistical study of this superlarge-scale structure (SLSS) by applying our core sampling, ...cluster, inertia tensor and minimal-spanning-tree analyses to the DURS. The results in the main support similar results from the complementary Las Campañas Redshift Survey (LCRS); the DURS is a fully three-dimensional, though shallower, survey, whilst the LCRS was carried out in six thin wedges of space. Because of the one-in-three sparse sampling used for DURS, the galaxy filaments of large-scale structure (LSS) are less clear here; the mean separation of ∼25 h−1 Mpc for the richer filaments is consistent with the LCRS result, but the poorer filaments are not seen in the DURS. In contrast, the analysis clearly picks out SLSS and we find, as with the LCRS, that ∼50 per cent of the galaxies lie within the SLSS in regions with overdensities of 5-10 times the mean galaxy density. It quantitatively demonstrates that SLSS is a major component of large-scale structure in the Universe. The SLSS is also confirmed as having statistical parameters similar to those for a sheet-like object, albeit a very irregular one with a highly inhomogeneous inner structure. The ‘mean-free path’, or average separation between SLSS structures, is found to be Ds≈50 h−1 Mpc. The inertia tensor analysis gives mean lengths, widths and thicknesses of ∼20-40, 10 and 5 h−1 Mpc, respectively, for the clusters of SLSS. In particular, the largest great wall in the DURS is found to have a length of ∼75 h−1 Mpc. Unlike the LCRS, the cluster mass function for the three-dimensional DURS has a high mass ‘tail’; such a ‘tail’ would constitute a quantitative signature for the presence of great walls. Finally, theoretical considerations would suggest that the results support arguments for the large-scale biasing of galaxies with respect to dark matter.
Haloes gone MAD14: The Halo-Finder Comparison Project Knebe, Alexander; Knollmann, Steffen R; Muldrew, Stuart I ...
Monthly notices of the Royal Astronomical Society,
06/2011, Letnik:
415, Številka:
3
Journal Article
Recenzirano
We present a detailed comparison of fundamental dark matter halo properties retrieved by a substantial number of different halo finders. These codes span a wide range of techniques including ...friends-of-friends, spherical-overdensity and phase-space-based algorithms. We further introduce a robust (and publicly available) suite of test scenarios that allow halo finder developers to compare the performance of their codes against those presented here. This set includes mock haloes containing various levels and distributions of substructure at a range of resolutions as well as a cosmological simulation of the large-scale structure of the universe.
All the halo-finding codes tested could successfully recover the spatial location of our mock haloes. They further returned lists of particles (potentially) belonging to the object that led to coinciding values for the maximum of the circular velocity profile and the radius where it is reached. All the finders based in configuration space struggled to recover substructure that was located close to the centre of the host halo, and the radial dependence of the mass recovered varies from finder to finder. Those finders based in phase space could resolve central substructure although they found difficulties in accurately recovering its properties. Through a resolution study we found that most of the finders could not reliably recover substructure containing fewer than 30-40 particles. However, also here the phase-space finders excelled by resolving substructure down to 10-20 particles. By comparing the halo finders using a high-resolution cosmological volume, we found that they agree remarkably well on fundamental properties of astrophysical significance (e.g. mass, position, velocity and peak of the rotation curve).
We further suggest to utilize the peak of the rotation curve, v
max, as a proxy for mass, given the arbitrariness in defining a proper halo edge.
Using high resolution DM simulations we study the shape of dark matter halos.
Halos become more spherical with decreasing mass. This trend is even more
pronounced for the inner part of the halo. ...Angular momentum and shape are
correlated. The angular momenta of neighboring halos are correlated.
Using high resolution DM simulations we study the shape of dark matter halos. Halos become more spherical with decreasing mass. This trend is even more pronounced for the inner part of the halo. ...Angular momentum and shape are correlated. The angular momenta of neighboring halos are correlated.
We present a comparison of major methodologies of fast generating mock halo or galaxy catalogues. The comparison is done for two-point and the three-point clustering statistics. The reference ...catalogues are drawn from the BigMultiDark N-body simulation. Both friend-of-friends (including distinct halos only) and spherical overdensity (including distinct halos and subhalos) catalogs have been used with the typical number density of a large-volume galaxy surveys. We demonstrate that a proper biasing model is essential for reproducing the power spectrum at quasilinear and even smaller scales. With respect to various clustering statistics a methodology based on perturbation theory and a realistic biasing model leads to very good agreement with N-body simulations. However, for the quadrupole of the correlation function or the power spectrum, only the method based on semi-N-body simulation could reach high accuracy (1% level) at small scales, i.e., r<25 Mpc/h or k>0.15 h/Mpc. Full N-body solutions will remain indispensable to produce reference catalogues. Nevertheless, we have demonstrated that the far more efficient approximate solvers can reach a few percent accuracy in terms of clustering statistics at the scales interesting for the large-scale structure analysis after calibration with a few reference N-body calculations. This makes them useful for massive production aimed at covariance studies, to scan large parameter spaces, and to estimate uncertainties in data analysis techniques, such as baryon acoustic oscillation reconstruction, redshift distortion measurements, etc.
abridged We present a detailed comparison of fundamental dark matter halo properties retrieved by a substantial number of different halo finders. These codes span a wide range of techniques including ...friends-of-friends (FOF), spherical-overdensity (SO) and phase-space based algorithms. We further introduce a robust (and publicly available) suite of test scenarios that allows halo finder developers to compare the performance of their codes against those presented here. This set includes mock haloes containing various levels and distributions of substructure at a range of resolutions as well as a cosmological simulation of the large-scale structure of the universe. All the halo finding codes tested could successfully recover the spatial location of our mock haloes. They further returned lists of particles (potentially) belonging to the object that led to coinciding values for the maximum of the circular velocity profile and the radius where it is reached. All the finders based in configuration space struggled to recover substructure that was located close to the centre of the host halo and the radial dependence of the mass recovered varies from finder to finder. Those finders based in phase space could resolve central substructure although they found difficulties in accurately recovering its properties. Via a resolution study we found that most of the finders could not reliably recover substructure containing fewer than 30-40 particles. However, also here the phase space finders excelled by resolving substructure down to 10-20 particles. By comparing the halo finders using a high resolution cosmological volume we found that they agree remarkably well on fundamental properties of astrophysical significance (e.g. mass, position, velocity, and peak of the rotation curve).
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