140 citations · 1.4k across the 46 of their papers we have counts for
38 papers · 1 filter
Post-collapse Lagrangian perturbation theory in three dimensions
Shohei Saga, Stéphane Colombi, Atsushi Taruya +2
The gravitational collapse of collisionless matter leads to shell-crossing singularities that challenge the applicability of standard perturbation theory. Here, we present the firs…
Angular bispectrum of matter number counts in cosmic structures
Thomas Montandon, Enea Di Dio, Cornelius Rampf +1
The bispectrum of galaxy number counts is a key probe of large-scale structure, offering insights into the initial conditions of the Universe, the nature of gravity, and cosmologic…
BullFrog: Multi-step perturbation theory as a time integrator for cosmological simulations
Cornelius Rampf, Florian List, Oliver Hahn
Modelling the cosmic large-scale structure can be done through numerical N-body simulations or by using perturbation theory. Here, we present an N-body approach that effectively im…
Starting Cosmological Simulations from the Big Bang
Florian List, Oliver Hahn, Cornelius Rampf
The cosmic large-scale structure (LSS) provides a unique testing ground for connecting fundamental physics to astronomical observations. Modeling the LSS requires numerical -bod…
Fast and accurate collapse-time predictions for collisionless matter
Cornelius Rampf, Shohei Saga, Atsushi Taruya +1
We consider the gravitational collapse of collisionless matter seeded by three crossed sine waves with various amplitudes, also in the presence of a linear external tidal field. We…
Relativistic matter bispectrum of cosmic structures on the light cone
Thomas Montandon, Julian Adamek, Oliver Hahn +4
Upcoming surveys of cosmic structures will probe scales close to the cosmological horizon, which opens up new opportunities for testing the cosmological concordance model to high a…
Renormalization group and UV completion of cosmological perturbations: Gravitational collapse as a critical phenomenon
Cornelius Rampf, Oliver Hahn
Cosmological perturbation theory is known to converge poorly for predicting the spherical collapse and void evolution of collisionless matter. Using the exact parametric solution a…
Analytical growth functions for cosmic structures in a CDM Universe
Cornelius Rampf, Sonja Ornella Schobesberger, Oliver Hahn
The cosmological fluid equations describe the early gravitational dynamics of cold dark matter (CDM), exposed to a uniform component of dark energy, the cosmological constant .…
Cosmological Vlasov-Poisson equations for dark matter: Recent developments and connections to selected plasma problems
Cornelius Rampf
The cosmic large-scale structures of the Universe are mainly the result of the gravitational instability of initially small density fluctuations in the dark-matter distribution. Da…
Shell-crossing in a CDM Universe
Cornelius Rampf, Oliver Hahn
Perturbation theory is an indispensable tool for studying the cosmic large-scale structure, and establishing its limits is therefore of utmost importance. One crucial limitation of…
Accurate initial conditions for cosmological N-body simulations: Minimizing truncation and discreteness errors
Michaël Michaux, Oliver Hahn, Cornelius Rampf +1
Inaccuracies in the initial conditions for cosmological N-body simulations could easily be the largest source of systematic error in predicting the non-linear large-scale structure…
Higher-order initial conditions for mixed baryon-CDM simulations
Oliver Hahn, Cornelius Rampf, Cora Uhlemann
We present a novel approach to generate higher-order initial conditions (ICs) for cosmological simulations that take into account the distinct evolution of baryons and dark matter.…
Cosmological perturbations for two cold fluids in CDM
Cornelius Rampf, Cora Uhlemann, Oliver Hahn
The cosmic large-scale structure of our Universe is comprised of baryons and cold dark matter (CDM). Yet it is customary to treat these two components as a combined single-matter f…
Fast simulations of cosmic large-scale structure with massive neutrinos
Christian Partmann, Christian Fidler, Cornelius Rampf +1
Accurate cosmological simulations that include the effect of non-linear matter clustering as well as of massive neutrinos are essential for measuring the neutrino mass scale from u…
Unveiling the singular dynamics in the cosmic large-scale structure
Cornelius Rampf, Uriel Frisch, Oliver Hahn
It is known that the gravitational collapse of cold dark matter leads to infinite-density caustics that seed the primordial dark-matter halos in the large-scale structure. The deve…
Semiclassical path to cosmic large-scale structure
Cora Uhlemann, Cornelius Rampf, Mateja Gosenca +1
We chart a path toward solving for the nonlinear gravitational dynamics of cold dark matter by relying on a semiclassical description using the propagator. The evolution of the pro…
A Relativistic Interpretation of Bias in Newtonian Simulations
Christian Fidler, Nils Sujata, Cornelius Rampf
Observables of cosmic structures are usually not the underlying matter field but biased tracers of matter, such as galaxies or halos. We show how the bias found in Newtonian N-body…
A new approach to cosmological structure formation with massive neutrinos
Christian Fidler, Alexander Kleinjohann, Thomas Tram +2
We show how Newtonian cosmological simulations can be employed to investigate the non-linear evolution of two particle species in a relativistic context. We discuss the application…
Quasi-spherical collapse of matter in CDM
Cornelius Rampf
We report the findings of new exact analytical solutions to the cosmological fluid equations, namely for the case where the initial conditions are perturbatively close to a spheric…
General relativistic weak-field limit and Newtonian N-body simulations
Christian Fidler, Thomas Tram, Cornelius Rampf +3
We show how standard Newtonian N-body simulations can be interpreted in terms of the weak-field limit of general relativity by employing the recently developed Newtonian motion gau…
Interacting neutrinos in cosmology: exact description and constraints
Isabel M. Oldengott, Thomas Tram, Cornelius Rampf +1
We consider the impact of neutrino self-interactions described by an effective four-fermion coupling on cosmological observations. Implementing the exact Boltzmann hierarchy for in…
Shell-crossing in quasi-one-dimensional flow
Cornelius Rampf, Uriel Frisch
Blow-up of solutions for the cosmological fluid equations, often dubbed shell-crossing or orbit crossing, denotes the breakdown of the single-stream regime of the cold-dark-matter…
Quasilinear observables in dark energy cosmologies
Cornelius Rampf, Eleonora Villa, Luca Amendola
What are the fundamental limitations of reconstructing the properties of dark energy, given cosmological observations in the quasilinear regime in a range of redshifts, to be as pr…
The effect of early radiation in N-body simulations of cosmic structure formation
Julian Adamek, Jacob Brandbyge, Christian Fidler +3
Newtonian N-body simulations have been employed successfully over the past decades for the simulation of the cosmological large-scale structure. Such simulations usually ignore rad…