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Methods are studied to compute the boosting effects produced by the observer motion that modifies and transfers to higher l the isotropic monopole frequency spectrum of the cosmic background. Explicit analytical solutions for spherical…

Cosmology and Nongalactic Astrophysics · Physics 2024-01-11 Tiziana Trombetti , Carlo Burigana , Marco Tucci , Luigi Toffolatti

We compute the two-loop effective field theory (EFT) power spectrum of dark matter density fluctuations in $\Lambda$CDM using the recently proposed COBRA method (Bakx. et al, 2025). With COBRA, we are able to evaluate the two-loop matter…

Cosmology and Nongalactic Astrophysics · Physics 2026-02-11 Thomas Bakx , Henrique Rubira , Nora Elisa Chisari , Zvonimir Vlah

A new computational scheme for the nonlinear cosmological matter power spectrum (PS) is presented. Our method is based on evolution equations in time, which can be cast in a form extremely convenient for fast numerical evaluations. A…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-05 Stefano Anselmi , Massimo Pietroni

We derive the one-loop perturbative formula of the redshift-space matter power spectrum after density field reconstruction in the Zeldovich approximation. We find that the reconstruction reduces the amplitudes of nonlinear one-loop…

Cosmology and Nongalactic Astrophysics · Physics 2020-02-19 Chiaki Hikage , Kazuya Koyama , Ryuichi Takahashi

The next generation of cosmological surveys will operate over unprecedented scales, and will therefore provide exciting new opportunities for testing general relativity. The standard method for modelling the structures that these surveys…

General Relativity and Quantum Cosmology · Physics 2018-03-28 Sophia R. Goldberg , Christopher Gallagher , Timothy Clifton

Perturbation theory is a powerful tool for studying large-scale structure formation in the universe and calculating observables such as the power spectrum or bispectrum. However, beyond linear order, typically this is done by assuming a…

Cosmology and Nongalactic Astrophysics · Physics 2023-08-09 Nicholas Choustikov , Zvonimir Vlah , Anthony Challinor

A new approach to cosmological perturbation theory has been recently introduced by Bartelmann et al., relying on nonequilibrium statistical theory of classical particles, and treating the gravitational interaction perturbatively. They…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-20 Yacine Ali-Haïmoud

We propose an efficient and model independent method for reconstructing the primordial power spectrum from Cosmic Microwave Background (CMB) and large scale structure observations. The algorithm is based on a Monte Carlo principle and…

Astrophysics · Physics 2009-11-10 Steen Hannestad

We investigate the building of unified models that can predict the matter-density power spectrum and the two-point correlation function from very large to small scales, being consistent with perturbation theory at low $k$ and with halo…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-19 Patrick Valageas , Takahiro Nishimichi

We investigate the question of how tightly we can constrain the cosmological parameters by using the ``cosmic inversion'' method in which we directly reconstruct the power spectrum of primordial curvature perturbations, $P(k)$, from the…

Astrophysics · Physics 2009-10-09 Noriyuki Kogo , Misao Sasaki , Jun'ichi Yokoyama

Rapid progress in cosmological Large Scale Structure (LSS) surveys motivates precise theoretical predictions. The Effective Field Theory of Large-Scale Structure (EFTofLSS) is routinely applied to data, and requires fast computation of its…

Cosmology and Nongalactic Astrophysics · Physics 2026-02-26 Charalampos Anastasiou , Andrea Favorito , Matthew Lewandowski , Leonardo Senatore , Henry Zheng

A newly developed method for systematically improving the convergence of path integrals for transition amplitudes, introduced in Phys. Rev. Lett. 94 (2005) 180403, Phys. Rev. B 72 (2005) 064302, Phys. Lett. A 344 (2005) 84, and expectation…

Statistical Mechanics · Physics 2011-08-08 Danica Stojiljkovic , Aleksandar Bogojevic , Antun Balaz

We study in detail how neutrino perturbations can be followed in linear theory by using only terms up to $l=2$ in the Boltzmann hierarchy. We provide a new approximation to the third moment and demonstrate that the neutrino power spectrum…

Cosmology and Nongalactic Astrophysics · Physics 2016-06-15 Maria Archidiacono , Steen Hannestad

We study the bispectrum in Lagrangian perturbation theory. Extending past results for the power spectrum, we describe a method to efficiently compute the bispectrum in LPT, focusing on the Zeldovich approximation, in which contributions due…

Cosmology and Nongalactic Astrophysics · Physics 2024-10-07 Shi-Fan Chen , Zvonimir Vlah , Martin White

We improve the algorithm of Kosowsky, Milosavljevic, and Jimenez (2002) for computing power spectra of the cosmic microwave background. The present algorithm computes not only the temperature power spectrum but also the E-mode polarization…

Astrophysics · Physics 2009-11-10 Raul Jimenez , Licia Verde , Hiranya Peiris , Arthur Kosowsky

We discuss a method of calculating the key cosmological parameters on the basis of a selected scale factor by using exact solutions of the background equations. We specify the formulas for calculating the power spectrum, the spectral…

General Relativity and Quantum Cosmology · Physics 2017-04-19 Sergey V. Chervon , Igor V. Fomin

The matter density field exhibits a nearly lognormal probability density distribution (PDF) after entering into the nonlinear regime. Recently, it has been shown that the shape of the power spectrum of a logarithmically transformed density…

Cosmology and Nongalactic Astrophysics · Physics 2015-03-19 Xin Wang , Mark Neyrinck , István Szapudi , Alex Szalay , Xuelei Chen , Julien Lesgourgues , Antonio Riotto , Martin Sloth

The nonlinear mass is a characteristic scale in halo formation that has wide-ranging applications across cosmology. Naively, computing it requires repeated numerical integration to calculate the variance of the power spectrum on different…

Cosmology and Nongalactic Astrophysics · Physics 2019-11-04 Alex Krolewski , Zachary Slepian

The perturbative approach to structure formation has recently received a lot of attention in the literature. In such setups the final predictions for observables like the power spectrum is often derived under additional approximations such…

Cosmology and Nongalactic Astrophysics · Physics 2016-12-14 Matteo Fasiello , Zvonimir Vlah

Gravity-induced non-Gaussianity in the large-scale structure of the Universe, characterised by higher-order statistics such as the bispectrum (three-point cumulant), is expected to contain rich cosmological information. A measurement of the…

Cosmology and Nongalactic Astrophysics · Physics 2018-10-24 Benjamin Bose , Atsushi Taruya