Séminaire Univers / |
| « A Bayesian detection of high-significance voids and its cosmological applications » |
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Rosa Malandrino |
| Cosmic voids are the largest objects emerging in the cosmic web, covering the majority of the volume of the Universe. They are a well-established probe to gather cosmological information from the large-scale structure, both from intrinsic summary statistics and through cross-correlation with the cosmic microwave background and weak lensing. Unfortunately, identifying voids in a galaxy catalog is challenging for multiple reasons: observational effects such as holes in the mask or magnitude selection hinder the detection process; galaxies are biased tracers of the underlying dark matter distribution; and it is non-trivial to estimate the detection significance and parameter uncertainties for individual voids.We use the Manticore posterior simulations, a set of constrained simulations of the large-scale structure that are consistent with the observed galaxy positions, effectively representing statistically independent realizations of the probability distribution of the cosmic web. In this Bayesian framework, we are able to assess the uncertainties of emerging structures and thus identify high-significance voids. This results in a catalog with posterior distribution of the void properties, as well as characterization of their full shapes. As a reliable template for density environment, we cross-correlate these high-significance voids with the cosmic microwave background, with a particular focus on detecting the Sunyaev-Zeldovich effect at low redshift. |
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mardi 13 janvier 2026 - 11:00 Salle des séminaires Évry Schatzman Institut d'Astrophysique de Paris |
| Pages web du séminaire / Seminar's webpage |