scholarly journals Simulations and symmetries

2020 ◽  
Vol 492 (4) ◽  
pp. 5754-5763 ◽  
Author(s):  
Chirag Modi ◽  
Shi-Fan Chen ◽  
Martin White
Keyword(s):  
Perturbation Theory ◽  
Power Spectrum ◽  
Galaxy Formation ◽  
Hybrid Approach ◽  
Limited Range ◽  
Real Space ◽  
Equivalent Model ◽  
The Real ◽  
Body Dynamics ◽  
The Cost

ABSTRACT We investigate the range of applicability of a model for the real-space power spectrum based on N-body dynamics and a (quadratic) Lagrangian bias expansion. This combination uses the highly accurate particle displacements that can be efficiently achieved by modern N-body methods with a symmetries-based bias expansion which describes the clustering of any tracer on large scales. We show that at low redshifts, and for moderately biased tracers, the substitution of N-body-determined dynamics improves over an equivalent model using perturbation theory by more than a factor of two in scale, while at high redshifts and for highly biased tracers the gains are more modest. This hybrid approach lends itself well to emulation. By removing the need to identify haloes and subhaloes, and by not requiring any galaxy-formation-related parameters to be included, the emulation task is significantly simplified at the cost of modelling a more limited range in scale.

scholarly journals Generating approximate halo catalogues for blind challenges in precision cosmology

2019 ◽  
Vol 485 (2) ◽  
pp. 2407-2416 ◽  
Author(s):  
Lehman H Garrison ◽  
Daniel J Eisenstein
Keyword(s):  
Dark Matter ◽  
Transfer Function ◽  
Power Spectrum ◽  
High Precision ◽  
Real Space ◽  
Dark Matter Halo ◽  
The Real ◽  
The Galaxy ◽  
Similar Accuracy ◽  
Better Than

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.

scholarly journals Spherical harmonic analysis of the PSCz galaxy catalogue: redshift distortions and the real-space power spectrum

1999 ◽  
Vol 305 (3) ◽  
pp. 527-546 ◽  
Author(s):  
H. Tadros ◽  
W. E. Ballinger ◽  
A. N. Taylor ◽  
A. F. Heavens ◽  
G. Efstathiou ◽  
...  
Keyword(s):  
Power Spectrum ◽  
Harmonic Analysis ◽  
Spherical Harmonic ◽  
Real Space ◽  
Spherical Harmonic Analysis ◽  
The Real

scholarly journals Perturbation theory approach for the power spectrum: from dark matter in real space to massive haloes in redshift space

2012 ◽  
Vol 2012 (11) ◽  
pp. 029-029 ◽  
Author(s):  
Héctor Gil-Marín ◽  
Christian Wagner ◽  
Licia Verde ◽  
Cristiano Porciani ◽  
Raul Jimenez
Keyword(s):  
Dark Matter ◽  
Perturbation Theory ◽  
Power Spectrum ◽  
Real Space ◽  
Theory Approach

scholarly journals The real-space power spectrum of IRAS galaxies on large scales and the redshift distortion

1995 ◽  
Vol 276 (1) ◽  
pp. L59-L63 ◽  
Author(s):  
W. E. Ballinger ◽  
A. F. Heavens ◽  
A. N. Taylor
Keyword(s):  
Power Spectrum ◽  
Real Space ◽  
The Real

The Cost-Effectiveness of Pre-school Peanut Oral Immunotherapy in the Real World Setting

2021 ◽  
Author(s):  
Marcus Shaker ◽  
Edmond S. Chan ◽  
Jennifer LP. Protudjer ◽  
Lianne Soller ◽  
Elissa M. Abrams ◽  
...  
Keyword(s):  
Cost Effectiveness ◽  
Real World ◽  
Oral Immunotherapy ◽  
The Real ◽  
Real World Setting ◽  
The Cost

scholarly journals Current Trends in Random Walks on Random Lattices

Mathematics ◽  
2021 ◽  
Vol 9 (10) ◽  
pp. 1148
Author(s):  
Jewgeni H. Dshalalow ◽  
Ryan T. White
Keyword(s):  
Random Walk ◽  
Random Walks ◽  
Real Time ◽  
Real Space ◽  
Historical Background ◽  
Escape Time ◽  
The Real ◽  
Current Trends ◽  
One Step ◽  
Time Position

In a classical random walk model, a walker moves through a deterministic d-dimensional integer lattice in one step at a time, without drifting in any direction. In a more advanced setting, a walker randomly moves over a randomly configured (non equidistant) lattice jumping a random number of steps. In some further variants, there is a limited access walker’s moves. That is, the walker’s movements are not available in real time. Instead, the observations are limited to some random epochs resulting in a delayed information about the real-time position of the walker, its escape time, and location outside a bounded subset of the real space. In this case we target the virtual first passage (or escape) time. Thus, unlike standard random walk problems, rather than crossing the boundary, we deal with the walker’s escape location arbitrarily distant from the boundary. In this paper, we give a short historical background on random walk, discuss various directions in the development of random walk theory, and survey most of our results obtained in the last 25–30 years, including the very recent ones dated 2020–21. Among different applications of such random walks, we discuss stock markets, stochastic networks, games, and queueing.

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