Euclid: Early Release Observations -- A preview of the Euclid era through a galaxy cluster magnifying lens

International audienceWe present the first analysis of the Euclid Early Release Observations (ERO) program that targets fields around two lensing clusters, Abell 2390 and Abell 2764. We use VIS and NISP imaging to produce photometric catalogs for a total of $\sim 500\,000$ objects. The imaging data reach a $5\,\sigma$ typical depth in the range 25.1-25.4 AB in the NISP bands, and 27.1-27.3 AB in the VIS band. Using the Lyman-break method in combination with photometric redshifts, we identify $30$ Lyman-break galaxy (LBG) candidates at z>6 and 139 extremely red sources (ERSs), most likely at lower redshift. The deeper VIS imaging compared to NISP means we can routinely identify high-redshift Lyman breaks of the order of $3$ magnitudes, which reduces contamination by brown dwarf stars and low-redshift galaxies. Spectroscopic follow-up campaigns of such bright sources will help constrain both the bright end of the ultraviolet galaxy luminosity function and the quasar luminosity function at z>6, and constrain the physical nature of these objects. Additionally, we have performed a combined strong lensing and weak lensing analysis of A2390, and demonstrate how Euclid will contribute to better constraining the virial mass of galaxy clusters. From these data, we also identify optical and near-infrared counterparts of known z>0.6 clusters, which exhibit strong lensing features, establishing the ability of Euclid to characterize high-redshift clusters. Finally, we provide a glimpse of Euclid's ability to map the intracluster light out to larger radii than current facilities, enabling a better understanding of the cluster assembly history and mapping of the dark matter distribution. This initial dataset illustrates the diverse spectrum of legacy science that will be enabled by the Euclid survey

Compte rendu de Annalisa MARZANO, Plants, politic and Empire in Ancient Rome, Cambridge, 2022

International audienc

Le saint face à ses parents. Les conflits familiaux dans les Vies latines tardo-antiques

International audienceLes scènes de conflit entre le héros et ses parents sont fréquentes dans les Vies de saint latines écrites entre le IVe et le VIe siècle. Elles jouent un rôle de transition entre le récit de l’enfance sainte et celui de la vie consacrée du protagoniste, marquant ainsi son entrée dans l’âge adulte et son rejet des projets mondains envisagés pour lui par ses parents. Plus topique qu’historique, ce motif narratif sert surtout à représenter l’opposition entre deux systèmes de valeurs : celui de la société traditionnelle romaine, puis chrétienne, et celui, plus radical, du mouvement monastique que les Vies présentent comme le moyen le plus sûr d’accéder à la sainteté

Compte rendu de Tobias BUSEN, Die römische Kaiservilla Pausylipon, Gesamtanlage und bauten des oberen Plateaus, Denckmäler Antiker Architektur 21, Berlin 2023

International audienc

A duality operators/Banach spaces

International audienceGiven a set $B$ of operators between subspaces of $L_p$ spaces, we characterize the operators between subspaces of $L_p$ spaces that remain bounded on the $X$-valued $L_p$ space for every Banach space on which elements of the original class $B$ are bounded. This is a form of the bipolar theorem for a duality between the class of Banach spaces and the class of operators between subspaces of $L_p$ spaces, essentially introduced by Pisier. The methods we introduce allow us to recover also the other direction --characterizing the bipolar of a set of Banach spaces--, which had been obtained by Hernandez in 1983

Essai de phénoménologie du consentement: Où situer la responsabilité dans l’acte de consentir ?

International audienceUne des thèses principales que je défends ici, c’est qu’aucun consentement ne vaut s’il n’est accompagné d’une responsabilité respective de chacun des deux acteurs. La question du consentement doit dans un premier temps être mûrement réfléchie ; ce n’est que lorsqu’elle est clairement explicitée que celui à qui on demande le consentement peut se l’approprier dans le vis-à-vis du premier acteur qui pose la question. Il faut que l’individu dont on sollicite le consentement soit en mesure de se l’approprier avant d’en être responsable, c’est-à-dire de pouvoir se sentir responsable de ce choix de consentir, démarche qui expose bien sûr ce dernier à assumer ce qu’il s’est lui-même imposé

On the space of subgroups of Baumslag-Solitar groups I: perfect kernel and phenotype

New version including the referee's suggestions. 63 pagesInternational audienceGiven a Baumslag-Solitar group, we study its space of subgroups from a topological and dynamical perspective. We first determine its perfect kernel (the largest closed subset without isolated points). We then bring to light a natural partition of the space of subgroups into one closed subset and countably many open subsets that are invariant under the action by conjugation. One of our main results is that the restriction of the action to each piece is topologically transitive. This partition is described by an arithmetically defined function, that we call the phenotype, with values in the positive integers or infinity. We eventually study the closure of each open piece and also the closure of their union. We moreover identify in each phenotype a (the) maximal compact invariant subspace

Gaussian framework and optimal projection of weather fields for prediction of extreme events

40 pages, 11 figures, 6 tablesInternational audienceExtreme events are the major weather related hazard for humanity. It is then of crucial importance to have a good understanding of their statistics and to be able to forecast them. However, lack of sufficient data makes their study particularly challenging. In this work we provide a simple framework to study extreme events that tackles the lack of data issue by using the whole dataset available, rather than focusing on the extremes in the dataset. To do so, we make the assumption that the set of predictors and the observable used to define the extreme event follow a jointly Gaussian distribution. This naturally gives the notion of an optimal projection of the predictors for forecasting the event. We take as a case study extreme heatwaves over France, and we test our method on an 8000-year-long intermediate complexity climate model time series and on the ERA5 reanalysis dataset. For a-posteriori statistics, we observe and motivate the fact that composite maps of very extreme events look similar to less extreme ones. For prediction, we show that our method is competitive with off-the-shelf neural networks on the long dataset and outperforms them on reanalysis. The optimal projection pattern, which makes our forecast intrinsically interpretable, highlights the importance of soil moisture deficit and quasi-stationary Rossby waves as precursors to extreme heatwaves

Asymptotic Equipartition Theorems in von Neumann algebras

Preliminary version. Comments are welcomeInternational audienceThe Asymptotic Equipartition Property (AEP) in information theory establishes that independent and identically distributed (i.i.d.) states behave in a way that is similar to uniform states. In particular, with appropriate smoothing, for such states both the min and the max relative entropy asymptotically coincide with the relative entropy. In this paper, we generalize several such equipartition properties to states on general von Neumann algebras. First, we show that the smooth max relative entropy of i.i.d. states on a von Neumann algebra has an asymptotic rate given by the quantum relative entropy. In fact, our AEP not only applies to states, but also to quantum channels with appropriate restrictions. In addition, going beyond the i.i.d. assumption, we show that for states that are produced by a sequential process of quantum channels, the smooth max relative entropy can be upper bounded by the sum of appropriate channel relative entropies. Our main technical contributions are to extend to the context of general von Neumann algebras a chain rule for quantum channels, as well as an additivity result for the channel relative entropy with a replacer channel

From parliamentary history to digital and computational history: a NLP-friendly TEI model for historical parliamentary proceedings

International audienceThis paper introduces a new method for the digital and computational analysis of historical parliamentary proceedings. The paper presents an XML-TEI model specifically designed for encoding historical parliamentary documents; this model is exemplified through the analysis of parliamentary debates from the French Chamber of Deputies (1889-1893). The first part of the paper discusses the motivations behind the model's development. The second part outlines the methodological choices in constructing the model and the need for schema adaptation. We subsequently detail our method for automatic encoding of such large corpora. Finally, we propose an approach to annotate parliamentary debates using natural language processing analyses, focusing on topic modelling