Perturbation Theory vs Simulation: Quasi-linear Scale, Binning Effect, and Visualization of Bispectrum

Tomlinson, Joseph; Jeong, Donghui

doi:10.48550/arxiv.2204.00668

Cited by 2 publications

(2 citation statements)

References 55 publications

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“…Other authors claim that even k max = 0.35 h/Mpc may result in unbiased constrains [61]. Moreover, since non-linearities are less important at higher redshifts, it is expected that k max should naturally increase as a function of redshift [62,63]. Therefore, regarding the present forecast, we consider as our baseline three maximal values for k: 0.1, 0.2 and 0.3 h/Mpc which we apply independently for each redshift bin.…”

Section: Comparison With Boss and Forecasts For Euclid And Desimentioning

confidence: 99%

Fisher matrix for the one-loop galaxy power spectrum: measuring expansion and growth rates without assuming a cosmological model

Amendola

Pietroni

Quartin

2022

J. Cosmol. Astropart. Phys.

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We introduce a methodology to extend the Fisher matrix forecasts to mildly non-linear scales without the need of selecting a cosmological model. We make use of standard non-linear perturbation theory for biased tracers complemented by counterterms, and assume that the cosmological distances can be measured accurately with standard candles. Instead of choosing a specific model, we parametrize the linear power spectrum and the growth rate in several k and z bins. We show that one can then obtain model-independent constraints of the expansion rate E(z) = E(z)/H 0 and the growth rate f(k,z), besides the bias functions. We apply the technique to both Euclid and DESI public specifications in the range 0.6 ≤ z ≤ 1.8 and show that the gain in precision when going from k max = 0.1 to 0.2 h/Mpc is around two- to threefold, while it reaches four- to ninefold when extending to k max = 0.3 h/Mpc. In absolute terms, with k max = 0.2 h/Mpc, one can reach high precision on E(z) at each z-shell: 8–10% for DESI with Δz = 0.1, 5–6% for Euclid with Δz = 0.2–0.3. This improves to 1–2% if the growth rate f is taken to be k-independent. The growth rate itself has in general much weaker constraints, unless assumed to be k-independent, in which case the gain is similar to the one for E(z) and uncertainties around 5–15% can be reached at each z-bin. We also discuss how neglecting the non-linear corrections can have a large effect on the constraints even for k max = 0.1 h/Mpc, unless one has independent strong prior information on the non-linear parameters.

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Section: Comparison With Boss and Forecasts For Euclid And Desimentioning

confidence: 99%

Fisher matrix for the one-loop galaxy power spectrum: measuring expansion and growth rates without assuming a cosmological model

Amendola

Pietroni

Quartin

2022

J. Cosmol. Astropart. Phys.

View full text Add to dashboard Cite

show abstract

“…This expectation, however, can only be tested on simulations and on real data, once the latter become available. Moreover, since non-linearities are less important at higher redshifts, it is expected that k max should naturally increase as a function of redshift [52,53]. Therefore, regarding the present forecast, we consider as our baseline three maximal values for k: 0.1, 0.2 and 0.3 h/Mpc which we apply independently for each redshift bin.…”

Section: Comparison With Boss and Forecasts For Euclid And Desimentioning

confidence: 99%

Fisher matrix for the one-loop galaxy power spectrum: measuring expansion and growth rates without assuming a cosmological model

Amendola¹,

Pietroni²,

Quartin³

2022

Preprint

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We introduce a methodology to extend the Fisher matrix forecasts to mildly nonlinear scales without the need of selecting a cosmological model. We make use of standard non-linear perturbation theory for biased tracers complemented by counterterms, and assume that the cosmological distances can be measured accurately with standard candles. Instead of choosing a specific model, we parametrize the linear power spectrum and the growth rate in several k and z bins. We show that one can then obtain model-independent constraints of the expansion rate H(z)/H 0 and the growth rate f (k, z), besides the bias functions. We apply the technique to both Euclid and DESI public specifications in the redshift range 0.6 − 1.8 and show that the precision on H(z) from increasing the cut-off scale improves abruptly for k max > 0.17 h/Mpc and reaches subpercent values for k max ≈ 0.3 h/Mpc. Overall, the gain in precision when going from k max = 0.1 h/Mpc to k max = 0.3 h/Mpc is around one order of magnitude. The growth rate has in general much weaker constraints, unless is assumed to be k-independent. In such case, the gain is similar to the one for H(z) and one can reach uncertainties around 5-10% at each z-bin. We also discuss how neglecting the non-linear corrections can have a large effect on the constraints even for k max = 0.1 h/Mpc, unless one has independent strong prior information on the non-linear parameters.

show abstract

Perturbation Theory vs Simulation: Quasi-linear Scale, Binning Effect, and Visualization of Bispectrum

Cited by 2 publications

References 55 publications

Fisher matrix for the one-loop galaxy power spectrum: measuring expansion and growth rates without assuming a cosmological model

Fisher matrix for the one-loop galaxy power spectrum: measuring expansion and growth rates without assuming a cosmological model

Fisher matrix for the one-loop galaxy power spectrum: measuring expansion and growth rates without assuming a cosmological model

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