Abstract
We present an optimized variant of the halo model, designed to produce
accurate matter power spectra well into the non-linear regime for a wide
range of cosmological models. To do this, we introduce physically
motivated free parameters into the halo-model formalism and fit these to
data from high-resolution N-body simulations. For a variety of Λ
cold dark matter (ΛCDM) and wCDM models, the halo-model power is
accurate to ≃ 5 per cent for k ≤ 10h Mpc-1 and z ≤
2. An advantage of our new halo model is that it can be adapted to
account for the effects of baryonic feedback on the power spectrum. We
demonstrate this by fitting the halo model to power spectra from the
OWLS (OverWhelmingly Large Simulations) hydrodynamical simulation suite
via parameters that govern halo internal structure. We are able to fit
all feedback models investigated at the 5 per cent level using only two
free parameters, and we place limits on the range of these halo
parameters for feedback models investigated by the OWLS simulations.
Accurate predictions to high k are vital for weak-lensing surveys, and
these halo parameters could be considered nuisance parameters to
marginalize over in future analyses to mitigate uncertainty regarding
the details of feedback. Finally, we investigate how lensing observables
predicted by our model compare to those from simulations and from
HALOFIT for a range of k-cuts and feedback models and quantify the
angular scales at which these effects become important. Code to
calculate power spectra from the model presented in this paper can be
found at https://github.com/alexander-mead/hmcode.
Original language | English |
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Pages (from-to) | 1958-1975 |
Number of pages | 18 |
Journal | Monthly Notices of the Royal Astronomical Society |
Volume | 454 |
Issue number | 2 |
Early online date | 9 Oct 2015 |
DOIs | |
Publication status | Published - 1 Dec 2015 |
Keywords
- gravitational lensing: weak
- cosmology: theory
- dark energy
- large-scale structure of Universe
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Catherine Heymans
- School of Physics and Astronomy - Personal Chair in Observational Cosmology
Person: Academic: Research Active