Séminaire Doctoral / Seminar PhD |
| « The prediction of the gravitational lensing signal through numerical simulations » |
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Céline Gouin |
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Upcoming weak lensing surveys like Euclid will provide an unprecedented opportunity to quantify the geometry and topology of the cosmic web, in particular in the vicinity of lensing clusters. Characterizing the connectivity of the cosmic web by weak lensing signal, an unbiased mass tracer, was the first goal of my thesis work.
As presented in my first paper (Gouin et al, 2017), I have used the PLUS N-body simulation to measure the projected density around massive galaxy clusters, and I have focused on multipolar moments of this signal to probe the azimuthal shape of clusters (inside and outside the virial radius). Computing the power spectrum of these moments, we observe a chromatic power excess at all scales, which is understood as the contraction of the primordial cosmic web driven by the growth of the cluster potential. Besides this boost, the quadrupole prevails in the cluster core (ellipsoidal shape), while at the outskirts, harmonic distortions are spread on small angular modes, and should represent the non-linear sharpening of the filamentary structures. We make predictions on the signal amplitude as a function of cluster-centric distance, mass and redshift and present the prospects for measuring it in current and future lensing data sets. Furthermore, with the advent of high performance computing, it has now become possible to address the problem of the complex interplay of baryons and dark matter on all relevant scales. In this context, we propose to predict the gravitational lensing signal (either strong or weak) with state-of art hydrodynamical cosmological simulation. |
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mercredi 19 avril 2017 - 17:00 Salle Entresol Daniel Chalonge, Institut d'Astrophysique |
| Page web du séminaire / Seminar's webpage |