COSMO19

Session

Parallel Sessions: Large Scale Structure (C.A.R.L., H09)

2 Sept 2019, 14:30

31. Relativistic effects in N-body simulations of cosmic large-scale structure

Dr Julian Adamek (Queen Mary University of London)

02/09/2019, 14:30

Large Scale Structure

Talk

As our advanced telescopes produce ever larger and deeper maps of our Universe we need to consider that observations are taken on our past light cone and on a spacetime geometry that is pervaded by small distortions. A precise understanding of the weak-field regime of General Relativity allows one to model these aspects consistently within N-body simulations of cosmic structure formation. The...

55. A trajectories approach to structure formation

Ms Fran Lane (University of Edinburgh)

02/09/2019, 14:50

Large Scale Structure

Talk

Our current perturbation theory techniques for predicting the power spectrum break down when we enter the non-linear regime (k~0.1 h/Mpc). Simulations allow us to probe this regime, however one must be run for every cosmology and gravity model one wishes to constrain. A perturbation theory technique that could push further into the non-linear scales than current methods and match the accuracy...

179. The lensing imprint of cosmic voids on the Cosmic Microwave Background

Umut Emek Demirbozan

02/09/2019, 15:10

Large Scale Structure

Talk

Cosmic voids gravitationally lens the cosmic microwave background (CMB) radiation, resulting in a distinct imprint on degree scales. We aimed to probe the consistency of simulated ΛCDM estimates and observed imprints of voids identified in the first year data set of the Dark Energy Survey (DES Y1) by cross correlating with CMB . In particular, we intended to explore other aspects of the...

216. Cosmological simulations for precision cosmology with large galaxy surveys

Dr Linda Blot (Max Planck Institute for Astrophysics)

02/09/2019, 15:30

Large Scale Structure

Talk

Large scale structure simulations are a fundamental tool to interpret data from large volume galaxy surveys. In fact, modelling the observables and their covariance is affected by the non-linear regime of gravitational collapse, a phenomenon that is best captured through simulations. In this talk I will present some applications of simulations that are relevant to present and upcoming galaxy...

66. Weak singularities in large-scale structure: identification and workaround

Cornelius Rampf

02/09/2019, 15:50

Large Scale Structure

Talk

The large-scale structure of the universe is mostly the consequence of the gravitational clustering of cold dark matter (CDM). Eventually the CDM trajectories begin to intersect ("shell-crossing"), which marks the starting point of elaborate computations in the phase-space. I show that, due to the collisionless nature of CDM, phase-space trajectories exhibit weakly singular behaviour such as...

203. Cosmic shear from KiDS

Prof. Konrad Kuijken (Leiden Observatory)

02/09/2019, 16:40

Large Scale Structure

Talk

The Kilo-Degree Survey is providing a weak gravitational lensing tomography map of the large-scale structure back to redshift ~1. We recently completed observations. First results, based on 1/3 of the final data set, indicate that the large-scale structure is slightly smoother than predicted in the best-fit Planck 2018 cosmology. I will discuss the methodology that led to this result, in...

98. Neutrino masses from cosmological perturbation theory

Anton Chudaykin (Institute for Nuclear Research)

02/09/2019, 17:05

Large Scale Structure

Talk

We present a realistic Markov-Chain Monte-Carlo (MCMC) forecast for the precision of neutrino mass and cosmological parameter measurements with a Euclid-like galaxy clustering survey. We use the most general perturbation theory model for the one-loop power galaxy spectrum and tree-level bispectrum. This model is based on cosmological perturbation theory and includes non-linear bias, redshhift...

229. Curved-Sky Weak Lensing Mass Map with the Dark Energy Survey Y3 data

Marco Gatti

02/09/2019, 17:25

Large Scale Structure

Talk

The statistical analysis of lensed galaxies is a powerful tool to study the dark matter distribution of the Universe. For instance, the distortion of galaxy shapes induced by the large scale structure of the Universe can be used to reconstruct the projected matter density along the line-of-sight (mass maps). Mass maps are useful as they provide a wealth of information that goes beyond and...

248. Relativistic dark matter bispectrum at one loop

Jorge Noreña (Pontificia Universidad Católica de Valparaíso)

02/09/2019, 17:45

Large Scale Structure

Talk

The large scale structure bispectrum in the squeezed limit couples large with small scales. Since relativity is important at large scales and non-linear loop corrections are important at small scales, the proper calculation of the observed bispectrum in this limit requires a non-linear relativistic calculation. We compute the matter bispectrum in general relativity in the weak field...

301. 1mn poster presentations

02/09/2019, 18:05

21. Developing a unified pipeline for large-scale structure data analysis with angular power spectra. The importance of redshift-space distortions for galaxy number counts

Konstantinos Tanidis (Università degli Studi di Torino)

03/09/2019, 14:30

Large Scale Structure

Talk

We develop a cosmological parameter estimation code for (tomographic) angular power spectra analyses of galaxy number counts, for which we include, for the first time, redshift-space distortions (RSD) in the Limber approximation. This allows for a speed-up in computation time, and we emphasise that only angular scales where the Limber approximation is valid are included in our analysis. Our...

23. KiDS+VIKING: Cosmic shear tomography with optical+infrared data

Hendrik Hildebrandt

03/09/2019, 14:55

Large Scale Structure

Talk

In this talk I will present new cosmic shear results based on the combined KiDS optical and VIKING infrared data over an area of 450 square degrees. I will show how the crucial redshift calibration benefits from the extended wavelength coverage and how this leads to more robust cosmological conclusions. The results will be put into context and compared to findings from the two other big cosmic...

174. An iterative reconstruction of cosmological initial density fields

Dr Ryuichiro Hada (Kavli IPMU, The University of Tokyo)

03/09/2019, 15:20

Large Scale Structure

Talk

We present an iterative method to reconstruct the linear-theory initial conditions from the late-time cosmological matter density field, with the intent of improving the recovery of the cosmic distance scale from the baryon acoustic oscillations (BAOs) and making the distance measurements more reliable in upcoming redshift surveys, e.g., PFS, DESI and Euclid. We apply the iterative method to...

302. Towards radio cosmology --- Spatial correlation functions from the LOFAR Two-metre Sky Survey

Dominik Schwarz

03/09/2019, 15:45

141. 65 (not 56) neutrinos per cubic centimetre

Philipp Mertsch (RWTH Aachen University)

03/09/2019, 16:40

Large Scale Structure

Talk

We revisit the clustering of relic neutrinos in the gravitational potential of the Milky Way. Previous work was based on forward-tracking of particles from high redshift. As the orbits of the neutrinos depend quite sensitively on their initial conditions, determining their density at a particular position, e.g. the sun, is however computationally inefficient. Consequently, the equations of...

84. Lensing of 21cm intensity mapping

Mrs Mona Jalilvand (University of Geneva)

03/09/2019, 17:00

Large Scale Structure

Talk

My talk has two parts. First, I talk about second-order lensing of 21cm intensity mapping (IM). Like the CMB, 21cm IM temperature fluctuations have second and higher order lensing and no first-order lensing. We find a new (third order) lensing term that is neglected in the CMB lensing but is important for 21cm IM. We study the detectability of 21cm IM lensing with a Fisher matrix approach for...

260. Implications of future large-scale structure observations for the neutrino mass sum

Thejs Brinckmann (RWTH Aachen)

03/09/2019, 17:15

Large Scale Structure

Talk

In the next decade we will almost certainly measure the neutrino mass sum to high significance. Neutrino cosmology faces a revolution due to upcoming large-scale structure surveys such as Euclid and DESI. Although accurate modelling of non-linear scales will be crucial for reaching high levels of significance, we will have a wealth of data from other sources as well: future CMB experiments...

264. Exploring the link between baryons and the matter power spectrum

Large Scale Structure

Talk

Upcoming weak lensing surveys require a detailed theoretical understanding of the matter power spectrum in order to derive accurate and precise cosmological parameter values. While galaxy formation is known to play an important role, its precise effects are currently unknown. We present the results of a detailed investigation of the dependence of the relative difference between the total...

40. Modeling shot noise in galaxy clustering statistics

Large Scale Structure

Poster

The precision to which we can constrain cosmological parameters is limited by sampling variance and shot noise. I will discuss the extent to which systematics in the shot noise modelling affect measurements of GR projection effects and fNL with the multi-tracer technique, and how these measurements could be optimized.I will also present measurements of the halo shot noise in halo bispectra...

86. Understanding high redshift structures from initial fluctuations until today

Large Scale Structure

Poster

This talk is dedicated to the modeling and constraint simulations of the distant Universe.
Introducing high redshift observations ($2.5>z>2$) galaxy and Lyman-$\alpha$ forest absorption observations, I will present the reconstruction of the dark matter density field and infer the initial fluctuations compatible with these structures.
Starting from here, I will show the results of our...