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Concept

Fluctuation primordiale de densité

Publications associées (32)

Euclid: The search for primordial features

Yiming Li, Frédéric Courbin, Georges Meylan

Primordial features, in particular oscillatory signals, imprinted in the primordial power spectrum of density perturbations represent a clear window of opportunity for detecting new physics at high-energy scales. Future spectroscopic and photometric measur ...

Edp Sciences S A2024

Primordial black hole isocurvature modes from non-Gaussianity

Raphaël van Laak

Primordial black holes (PBHs) are black holes that might have formed in high density regions in the early universe. The presence of local-type non-Gaussianity can lead to large-scale fluctuations in the PBH formation rate. If PBHs make up a non-negligible ...

IOP Publishing Ltd2023

The formation of the faintest galaxies in cosmological simulations: from the impact of primordial magnetic fields to the metal enrichment of present day dwarfs by first stars

Mahsa Sanati

In the theory of the bottom-up assembly of cosmic structures, one of the main challenges is to connect the smallest, most inconspicuous galaxies we observe today to the building blocks of more massive galaxies such as our own, the Milky Way. Do these so-ca ...

EPFL2023

Probing the nature of Dark Energy through the study of large scale structures using spectroscopic surveys and their simulations

Andrei Variu

Measurements of large-scale structure (LSS), as performed on the largest 3D map of over two million extragalactic sources from the Sloan Digital Sky Survey, together with measurements of the cosmic microwave background (CMB) anisotropies, are in complete a ...

EPFL2023

Detectability of Large Correlation Length Inflationary Magnetic Field with Cherenkov Telescopes

Andrii Neronov

Magnetic fields occupying the voids of the large scale structure may be a relic from the Early Universe originating from either Inflation or from cosmological phase transitions. We explore the possibility of identifying the inflationary origin of the void ...

2022

BOSS Correlation Function analysis from the Effective Field Theory of Large-Scale Structure

Cheng Zhao

After calibrating the predictions of the Effective Field Theory of Large-Scale Structure against several sets of simulations, as well as implementing a new method to assert the scale cut of the theory without the use of any simulation, we analyze the Full ...

IOP Publishing Ltd2022

Euclid : Effects of sample covariance on the number counts of galaxy clusters

Yi Wang, Georges Meylan

Aims. We investigate the contribution of shot-noise and sample variance to uncertainties in the cosmological parameter constraints inferred from cluster number counts, in the context of the Euclid survey. ...

EDP SCIENCES S A2021

Does concentration drive the scatter in the stellar-to-halo mass relation of galaxy clusters?

Jean-Paul Richard Kneib, Huanyuan Shan

Concentration is one of the key dark matter halo properties that could drive the scatter in the stellar-to-halo mass relation of massive clusters. We derive robust photometric stellar masses for a sample of brightest central galaxies (BCGs) in SDSS REDMAPP ...

OXFORD UNIV PRESS2021

Higgs inflation in Einstein-Cartan gravity

Mikhail Chapochnikov, Inar Timiryasov, Andrey Shkerin, Sebastian Zell

We study inflation driven by the Higgs field in the Einstein-Cartan formulation of gravity. In this theory, the presence of the Holst and Nieh-Yan terms with the Higgs field non-minimally coupled to them leads to three additional coupling constants. For a ...

IOP PUBLISHING LTD2021

Constraining the primordial magnetic field with dwarf galaxy simulations

Pascale Jablonka, Yves Revaz, Salim Bennouna, Mahsa Sanati

Using a set of cosmological hydro-dynamical simulations, we constrained the properties of primordial magnetic fields by studying their impact on the formation and evolution of dwarf galaxies. We performed a large set of simulations (8 dark matter only and ...

EDP SCIENCES S A2020

Probing the gravitational wave background from cosmic strings with LISA

Daniel Garcia Figueroa

Cosmic string networks offer one of the best prospects for detection of cosmological gravitational waves (GWs). The combined incoherent GW emission of a large number of string loops leads to a stochastic GW background (SGWB), which encodes the properties o ...

2020

Improving baryon acoustic oscillation measurement with the combination of cosmic voids and galaxies

Cheng Zhao, Andrei Variu

We develop a methodology to optimize the measurement of baryon acoustic oscillation (BAO) from a given galaxy sample. In our previous work, we demonstrated that one can measure BAO from tracers in underdense regions (voids). In this study, we combine the o ...

OXFORD UNIV PRESS2020

Inflationary perturbations with Lifshitz scaling

Sergey Sibiryakov

Instead of Lorentz invariance, gravitational degrees of freedom may obey Lifshitz scaling at high energies, as it happens in Horava's proposal for quantum gravity. We study consequences of this proposal for the spectra of primordial perturbations generated ...

IOP PUBLISHING LTD2019

Inconsistency of an inflationary sector coupled only to Einstein gravity

Daniel Garcia Figueroa, Erwin Handoko Tanin

From a model-building perspective, the inflationary sector might very well have no direct couplings to other species, apart from inevitable gravitational interactions. Within the context of General Relativity, a thermal universe can still emerge after infl ...

IOP PUBLISHING LTD2019

Backreaction of electromagnetic fields and the Schwinger effect in pseudoscalar inflation magnetogenesis

Oleksandr Sobol

We study magnetogenesis in axionlike inflation driven by a pseudoscalar field phi coupled axially to the electromagnetic (EM) field (beta/M-p)phi F-mu nu(F) over tilde mu nu with dimensionless coupling constant beta. A set of equations for the inflaton fie ...

American Physical Society2019

Ability of LIGO and LISA to probe the equation of state of the early Universe

Daniel Garcia Figueroa

The expansion history of the Universe between the end of inflation and the onset of radiation-domination (RD) is currently unknown. If the equation of state during this period is stiffer than that of radiation, w > 1/3, the gravitational wave (GW) backgrou ...

IOP PUBLISHING LTD2019

Cosmological Constraints from Multiple Probes in the Dark Energy Survey

Mingkui Wang, Yi Zhang, Eduardo Sanchez, Jonathan Andrew Blazek

The combination of multiple observational probes has long been advocated as a powerful technique to constrain cosmological parameters, in particular dark energy. The Dark Energy Survey has measured 207 spectroscopically confirmed type Ia supernova light cu ...

AMER PHYSICAL SOC2019

V-band nanosecond-scale pulse reflectometer diagnostic in the TCV tokamak

Stefano Coda, Laurie Porte, Pedro Andres Molina Cabrera

This article describes the realization of a novel approach to short pulse (∼1 ns) reflectometry (SPR) recently implemented in the tokamak configuration variable tokamak. Taking advantage of a fast arbitrary waveform generator and vector-network-analyzer ex ...

2019

Influence of backreaction of electric fields and Schwinger effect on inflationary magnetogenesis

Oleksandr Sobol

We study the generation of electromagnetic fields during inflation when the conformal invariance of Maxwell's action is broken by the kinetic coupling f(2)(phi)F mu nu F mu nu of the electromagnetic field to the inflaton field phi We consider the case wher ...

American Physical Society2018

Euclidean classical solutions in quantum field theory and gravity: Higgs vacuum metastability and the hierarchy problem

Andrey Shkerin

The thesis is dedicated to two groups of questions arising in modern particle physics and cosmology. The first group concerns with the problem of stability of the electroweak (EW) vacuum in different environments. Due to its phenomenological significance, ...

EPFL2018