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We present $\mathcal{O}(N^2)$ estimators for the small-scale power spectrum and bispectrum in cosmological simulations. In combination with traditional methods, these allow spectra to be efficiently computed across a vast range of scales,…

Cosmology and Nongalactic Astrophysics · Physics 2021-01-21 Oliver H. E. Philcox

Nonlinear effects are crucial in order to compute the cosmological matter power spectrum to the accuracy required by future generation surveys. Here, a new approach is presented, in which the power spectrum, the bispectrum and higher order…

Astrophysics · Physics 2009-11-13 Massimo Pietroni

We extend field-level inference to jointly constrain the cosmological parameters $\{A,\omega_{\rm cdm},H_0\}$, in both real and redshift space. Our analyses are based on mock data generated using a perturbative forward model, with noise…

Cosmology and Nongalactic Astrophysics · Physics 2025-09-25 Kazuyuki Akitsu , Marko Simonović , Shi-Fan Chen , Giovanni Cabass , Matias Zaldarriaga

Modeling the large-scale structure of the universe on nonlinear scales has the potential to substantially increase the science return of upcoming surveys by increasing the number of modes available for model comparisons. One way to achieve…

Cosmology and Nongalactic Astrophysics · Physics 2016-11-30 Marcel Schmittfull , Zvonimir Vlah

In this paper, we predict the covariance matrices of both the power spectrum and the bispectrum, including full non-Gaussian contributions, redshift space distortions, linear bias effects and shot-noise corrections, using perturbation…

Cosmology and Nongalactic Astrophysics · Physics 2020-07-15 Naonori S. Sugiyama , Shun Saito , Florian Beutler , Hee-Jong Seo

The usual fluid equations describing the large-scale evolution of mass density in the universe can be written as local in the density, velocity divergence, and velocity potential fields. As a result, the perturbative expansion in small…

Cosmology and Nongalactic Astrophysics · Physics 2016-06-01 Marcel Schmittfull , Zvonimir Vlah , Patrick McDonald

We explore the Lagrangian perturbation theory (LPT) at 1-loop order with Gaussian initial conditions. We present an expansion method to approximately compute the power spectrum in LPT. Our approximate solution has good convergence in the…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-17 Naonori S. Sugiyama

Perturbation theory (PT) is often used to model statistical observables capturing the translation and rotation-invariant information in cosmological density fields. PT produces higher-order corrections by integration over linear statistics…

Cosmology and Nongalactic Astrophysics · Physics 2018-12-07 Zachary Slepian

We consider approaches to cosmological parameter estimation in the inflationary cosmology, focussing on the required accuracy of the initial power spectra. Parametrizing the spectra, for example by power-laws, is well suited to testing the…

Astrophysics · Physics 2009-11-07 Samuel M. Leach , Andrew R. Liddle , Jerome Martin , Dominik J. Schwarz

We present a new analytic approach to describe large scale structure formation in the mildly non-linear regime. The central object of the method is the time-dependent probability distribution function generating correlators of the…

Cosmology and Nongalactic Astrophysics · Physics 2016-08-09 Diego Blas , Mathias Garny , Mikhail M. Ivanov , Sergey Sibiryakov

We present a calculation of the matter power spectrum covariance matrix ${\rm Cov}(\bf{k}_1,\bf{k}_2)$ that uses power spectrum responses to accurately describe the coupling between large- and small-scale modes beyond the perturbative…

Cosmology and Nongalactic Astrophysics · Physics 2017-12-13 Alexandre Barreira , Fabian Schmidt

We apply the effective field theory approach to the coupled metric-inflaton system, in order to investigate the impact of higher dimension operators on the spectrum of scalar and tensor perturbations in the short-wavelength regime. In both…

High Energy Physics - Theory · Physics 2009-09-28 Cristian Armendariz-Picon , Michele Fontanini , Riccardo Penco , Mark Trodden

Markov Chain Monte Carlo (MCMC) techniques are now widely used for cosmological parameter estimation. Chains are generated to sample the posterior probability distribution obtained following the Bayesian approach. An important issue is how…

In Papers I-III [arXiv:2210.10435, arXiv:2210.11085, arXiv:2304.13304], we use the flat-sky and distant-observer approximations to develop a formalism with which the correlation statistics of cosmological tensor fields are calculated by the…

Cosmology and Nongalactic Astrophysics · Physics 2024-09-23 Takahiko Matsubara

We present a fast method for estimating the cosmic microwave background polarization power spectra using unbiased estimates of heuristically-weighted correlation functions. This extends the O(N_pix^(3/2)) method of Szapudi et al. (2001) to…

Astrophysics · Physics 2009-11-07 Gayoung Chon , Anthony Challinor , Simon Prunet , Eric Hivon , Istvan Szapudi

The phase-integral approximation devised by Fr\"oman and Fr\"oman, is used for computing cosmological perturbations in the power-law inflationary model. The phase-integral formulas for the scalar and tensor power spectra are explicitly…

Astrophysics · Physics 2008-11-26 Clara Rojas , Victor M. Villalba

$ $Future surveys could obtain tighter constraints on the cosmological parameters with the galaxy power spectrum than with the Cosmic Microwave Background. However, the inclusion of multiple overlapping tracers, redshift bins, and more…

Cosmology and Nongalactic Astrophysics · Physics 2024-09-24 Yan Lai , Cullan Howlett , Tamara M. Davis

Standard cosmological perturbation theory (SPT) for the Large Scale Structure (LSS) of the Universe fails at small scales (UV) due to strong nonlinearities and to multistreaming effects. In Pietroni et al. 2011 a new framework was proposed…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-22 Alessandro Manzotti , Marco Peloso , Massimo Pietroni , Matteo Viel , Francisco Villaescusa-Navarro

We investigate the accuracy of Eulerian perturbation theory for describing the matter and galaxy power spectra in real and redshift space in light of future observational probes for precision cosmology. Comparing the analytical results with…

Cosmology and Nongalactic Astrophysics · Physics 2012-12-05 Héctor Gil-Marín , Christian Wagner , Licia Verde , Cristiano Porciani , Raul Jimenez

We investigate how unified models should be built to be able to predict the matter-density bispectrum (and power spectrum) from very large to small scales and that are at the same time consistent with perturbation theory at low $k$ and with…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-27 Patrick Valageas , Takahiro Nishimichi