Présidents de session
Science talks: Solar System, Milky Way and Transients
- Johan Bregeon (IN2P3 LSPC)
Science talks: Clusters
- Marina Ricci
Science talks: Supernovæ and photo-z
- Marine Kuna (UGA / LPSC)
Science talks: Clusters and misc.
- Cyrille Doux (LPSC)
Science talks: Photo-z
- Johan Bregeon (IN2P3 LSPC)
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Guillaume Dubus (IPAG), Jérôme Bouvier (IPAG)07/06/2023 16:00
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Daniel HESTROFFER (IMCCE/Paris observatory, CNRS, univ. PSL)07/06/2023 16:30
The dynamics of small Solar System bodies well beyond Neptune has the particularity that --- being at the interface of the heliosphere and the interstellar medium --- it involves gravitational effects coming from both the Solar System and from the Galactic environment in which it evolves.
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Our goal is to understand how such interactions are crucial in shaping the outer Solar system, up to the... -
Maria Pruzhinskaya (LPC)07/06/2023 16:45
The detection of new astronomical sources is one of the most anticipated outcomes of the next generation of large-scale sky surveys. Experiments such as the Vera Rubin Observatory Legacy Survey of Space and Time are expected to continuously monitor large areas of the sky with remarkable deliberation, which will undoubtedly lead to the detection of unforeseen astrophysical phenomena. At the...
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Julius Hrivnac (IJCLab)07/06/2023 17:00
Fink Broker stores received LSST alerts in a hybrid storage, where bulk data are stored in the NoSQL HBase database and their principal relations are captured by the associated Graph database. This data architecture allows a fast navigation in the data and offers advanced algorithms for the search of the hidden structures and relations using Graph theory approaches.
The talk will present...
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Nathan Amouroux08/06/2023 09:30
AMICO is an algorithm for the detection of galaxy clusters in photometric surveys, being implemented in DESC. AMICO has been successfully run on cosmoDC2 and the characterization of the produced catalog will be presented (e.g. completeness, purity and mass-richness relation). A first comparison to redMaPPer results will also be presented, highlighting the galaxy population differences between...
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Calum Murray (APC , University of Paris)08/06/2023 09:45
In this talk I will present the effects of gravitational lensing induced by the motion of massive objects. This is a relativistic effect and is much weaker than the deflection of light by density inhomogeneities. I show that while subdominant to the density term future surveys will be able to measure this effect by cross-correlating the lensing convergence field with a reconstructed...
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Manon Ramel (LPSC / IN2P3)08/06/2023 10:00
Galaxy clusters trace the highest peaks in the density of the Universe. Therefore, their abundance is a powerful probe to constrain cosmological parameters, expansion of the Universe and give information on the growth of structures. However, since their density of galaxies is significantly higher, these latter may appear to overlap on the line of sight and have their respective fluxes blended....
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Kirill Grishin (Universite de Paris)08/06/2023 10:15
The distribution of galaxy clusters, the largest gravitationally bound structures in the Universe, helps us to estimate fundamental constants and constrain different cosmological models. With the expected development and commissioning of astronomical instruments, such as LSST, in the next decade, the depth of imaging data for a significant area of the sky will allow us to select nearly...
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Damiano Rosselli (CPPM)08/06/2023 14:00
The goal of the project is to produce realistic forecast for $f\sigma_8$ measurement using peculiar velocities derived from Supernovae Type Ia. We will expand the work done for ZTF by Carreres et al. (https://arxiv.org/abs/2303.01198)
It is possible to measure peculiar velocities of Supernovae Type Ia by comparing their estimated distances from the Hubble Diagram with the redshifts of their...
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Madeleine Ginolin (IP2I/IN2P3/CNRS)08/06/2023 14:15
I will present the ZTF DR2 final sample of SNe Ia. I will focus on the study of standardisation process, with the study of the linearity of the standardisation relations used for cosmology analysis, as well as the dependency of standardisation on SNe host properties.
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joseph chevalier (IJCLab - A2C)08/06/2023 14:30
Following up on the work performed by J. Cohen-Tanugi, E. Nuss, E. Giraud and R. Ansari with FORS2 data, which aims to provide a new set of templates for photometric redshifts estimation in large surveys like LSST, this work focuses on the ways to select and prepare spectral templates from the dataset derived from observations.
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Several data reduction methods have been used and photo-z... -
Tom Colin (APC)09/06/2023 09:30
The halos mass function is the core of the theoretical part for constraining cosmology with galaxy cluster abundance. As it has been tested in other DESC projets, the current implementations of the halo mass function available in CCL (ex: Tinker 2008, Bocquet 2016, etc.) do not describe the mass distribution of dark matter halos found on the cosmoDC2 simulation at the percent level. The goal...
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Rance Solomon (LAPP)09/06/2023 09:45
Galaxy clusters can provide strong constraints on cosmic evolution and as such play a central role in the Dark Energy Science Collaboration efforts. In the era of big cosmological surveys, such as the nearing LSST run, optimized cluster finding algorithms are a necessary tool in the data pipeline process with a few finders already strongly developed: redMaPPer, WaZP, and AMICO. The redMaPPer...
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EDUARDO BARROSO (LPSC)09/06/2023 10:00
This paper proposes a novel approach to generate samples from target distributions that are difficult to sample from using Markov Chain Monte Carlo (MCMC) methods. Traditional MCMC algorithms often face slow convergence due to the difficulty in finding proposals that suit the problem at hand. To address this issue, the paper introduces the Approximate Posterior Ensemble Sampler (APES)...
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Thierry Souverin09/06/2023 10:15
The number of type Ia supernova observations will see significant growth within the next decade, especially thanks to the Legacy Survey of Space and Time undertaken by the Vera Rubin Observatory in Chile. With this increase, statistical uncertainties will decrease and flux calibration will become the main uncertainty for the characterization of dark energy. To deal with this issue, the...
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Dr Vincent Reverdy (Laboratoire d'Annecy de Physique des Particules)09/06/2023 14:00
Redshift measurements are the backbone of modern cosmology. But what is exactly a redshift and how to correctly interpret it? In this talk, I will present a short review of the state of the art of raytracing simulations, why correctly interpreting redshifts might be far more subtle than one could initially think of, and how it may affect cosmological analyses within the LSST survey.
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Valentin Brekke (APC/IN2P3)09/06/2023 14:15
We will describe a project to test and validate several machine learning techniques to estimate photometric redshift using multi-wavelength galaxy images. This project consists of machine network insertion in RAIL, testing and validation. We will validate and test on both field and cluster galaxies, and for individual and blended galaxies. Our results will be published in several papers lead...
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Michel Aguena (APC)09/06/2023 14:30
The abundance of galaxy clusters is a powerful probe for cosmology, especially on large optical surveys where hundreds of thousands can be detected. One of the main techniques that allows us to evaluate the large number of composing galaxies at a low cost is the photometric estimation of redshifts, i. e. photo-zs. Here we intend to evaluate the propagation of the uncertainties of photo-zs on...
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Simona Mei (APC/IN2P3)09/06/2023 14:45
The Rubin Galaxies collaboration (https://sites.google.com/view/lsstgsc/home) is focused on the scientific exploitation of Rubin observations for galaxy science. We will present the collaboration working packages and how to join. We will advertise the nest collaboration meeting on June 12th-14th in Paris.
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