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The impact of lunar topography on the 21-cm power spectrum for grid-based arrays : Insights for the Dark-ages EXplorer (DEX)
No full textInternational audienceThe Dark Ages (DA) provides a crucial window into the physics of the infant Universe, with the 21-cm signal offering the only direct probe for mapping out the three-dimensional distribution of matter at this epoch. To measure this cosmological signal, the Dark-ages EXplorer (DEX) has been proposed as a compact, grid-based radio array on the lunar farside. The minimal design consists of a 32 32 array of 3-m dipole antennas, operating in the MHz band. A practical challenge on the lunar surface is that the antennas may get displaced from their intended positions due to deployment imprecisions and non-coplanarity arising from local surface undulations. We present, for the first time, an end-to-end simulation pipeline, called SPADE-21cm, that integrates a sky model with a DA 21-cm signal model simulated in the lunar frame and incorporating lunar topography data. We study the effects of both lateral (xy) and vertical (z) offsets on the two-dimensional power spectra across the MHz and MHz spectral windows, with tolerance thresholds derived only for the latter. Our results show that positional offsets bias the power spectrum by per cent relative to the expected 21-cm power spectrum during DA. Lateral offsets within (at 32.5 MHz) keep the fraction of Fourier modes with strong contamination (> 50 per cent of the signal) to less than 1 per cent, whereas vertical height offsets affect a larger fraction. This conclusion holds for the 21-cm window with cMpc over the range of cMpc
The relationship between warm and hot gas-phase metallicity in massive elliptical galaxies and the influence of AGN feedback
No full textInternational audienceWarm ionized gas is ubiquitous at the centers of X-ray bright elliptical galaxies. While it is believed to play a key role in the feeding and feedback processes of supermassive black holes, its origins remain under debate. Existing studies have primarily focused on the morphology and kinematics of warm ionized gas. This work aims to provide a new perspective on warm (10,000 K) ionized gas and its connection to X-ray-emitting hot gas (>10^6 K) by measuring and comparing their metallicities. We conducted a joint analysis of 13 massive elliptical galaxies using MUSE/VLT and Chandra observations. Emission-line ratios were measured for the warm ionized gas using MUSE observation, and used to infer the ionization mechanisms and derive metallicities of the warm ionized gas using HII, and LIN(E)R calibrations. We also computed the warm phase metallicity using X-ray/EUV, and pAGB stars models. For two sources at higher redshift, direct Te method was also used to measure warm gas metallicities. Our observations reveal that most sources exhibit composite ionization, with contributions from both star formation and LINER-like emission. A positive linear correlation was found between the gas-phase metallicities of the warm and hot phases, ranging from 0.3 to 1.5 Zsun, and suggest the intimate connection between the two gas phases, likely driven by gas cooling and/or mixing. In some sources the warm gas metallicity shows a central drop. A similar radial trend has been reported for the hot gas metallicity in some galaxy clusters. The ionization mechanisms of cooling flow elliptical galaxies are diverse, suggesting multiple channels for powering the warm ionized gas. The large variation in the warm gas metallicity further suggests that cold gas mass derived under the assumption of solar metallicity for the CO-to-H2 conversion factor needs to be revised by approximately an order of magnitude
X-ray emission spectroscopy in liquid jets: A effective tool to probe valence and <i>p</i>-shells in organometallics and the influence of the solvation
No full textInternational audienceIn this combined experimental and theoretical work, we present state-of-the art liquid jet experiments based on X-ray emission spectroscopy of the [Fe(CN)6]4- and [Fe(CN)6]3--molecular ions in the hard-X-ray energy range. The ab-initio simulations of the valence-to-core and Kβ spectra reveal insights on the valence and metal's d-shells respectively. These results open new perspectives for applying spectroscopy to organometallic complexes in order to disentangle and probe various environmental effects including solvent interactions, pH variations, as well as ligand field influences and dynamical processes such as charge transfer or photoinduced ligand exchange reactions like photoaquation in solution
Case report and literature review of neurodevelopmental syndrome linked to DOT1L variants
No full textInternational audienceIntroduction: The DOT1L gene encodes a histone lysine methyltransferase that has the distinctive characteristic of being composed of a DOT1 catalytic domain that targets lysine 79 of the core globular domain of histone H3. DOT1L missense variants have recently been implicated in an autosomal dominant inheritance syndrome with developmental delay and congenital anomalies in postnatal cohorts. We report the twenty-sixth patient with this disorder.Methods: Trio genome sequencing (GS) was performed in a patient with developmental delay.Results: Clinical examination showed a predominant global developmental delay affecting language, with cerebral abnormalities visible on magnetic resonance imaging, hypotonia, and ophthalmological and musculoskeletal abnormalities. GS revealed a de novo heterozygous missense variant in exon 3 of DOT1L (c.161C > T; p.(Ala54Val)), which is reported for the first time as the cause of developmental delay and congenital anomalies.Discussion: Among the 26 reported patients, 23 have missense variants, two have truncating variants, and one has an in-frame deletion. The mode of transmission is predominantly de novo. Current studies indicate multiple pathogenic mechanisms underlying DOT1L-related disorder, including both gain-of-function and loss-of-function effects, underscoring the complexity of the disease etiology. Although the gene exhibits intolerance to loss-of-function variants, a considerable number of truncating variants are observed in control populations, suggesting incomplete penetrance and heterogeneity in the phenotypic expression of DOT1L-associated disorder. No phenotype-genotype correlation could be established. Among reported patients, including ours, the most consistent clinical manifestations are global developmental delay, predominantly affecting language and behavior, and possibly distinctive facial features
CTAO LST-1 observations of magnetar SGR 1935+2154: Deep limits on sub-second bursts and persistent tera-electronvolt emission
No full textInternational audienceThe Galactic magnetar SGR 1935+2154 has exhibited prolific high-energy (HE) bursting activity in recent years. Investigating its potential tera-electronvolt counterpart could provide insights into the underlying mechanisms of magnetar emission and very high-energy (VHE) processes in extreme astrophysical environments. We aim to search for a possible tera-electronvolt counterpart to both its persistent and sub-second-scale burst emission. We analysed over 25 h of observations from the Large-Sized Telescope prototype (LST-1) of the Cherenkov Telescope Array Observatory (CTAO) during periods of HE activity from SGR 1935+2154 in 2021 and 2022 to search for persistent emission. For bursting emission, we selected and analysed nine 0.1 s time windows centred around known short X-ray bursts, targeting potential sub-second-scale tera-electronvolt counterparts in a low-photon-statistics regime. While no persistent or bursting emission was detected in our search, we establish upper limits for the tera-electronvolt emission of a short magnetar burst simultaneous to its soft gamma-ray flux. Specifically, for the brightest burst in our sample, the ratio between tera-electronvolt and X-ray flux is less than . The non-detection of either persistent or bursting tera-electronvolt emission from SGR 1935+2154 suggests that if such components exist, they may occur under specific conditions not covered by our observations. This aligns with theoretical predictions of VHE components in magnetar-powered fast radio bursts and the detection of MeV - GeV emission in giant magnetar flares. These findings underscore the potential of magnetars, fast radio bursts, and other fast transients as promising candidates for future observations in the low-photon-statistics regime with Imaging Atmospheric Cherenkov Telescopes, particularly with the CTAO
Statistical Indications of Toponium Formation in Top Quark Pair Production
No full textInternational audienceWe present an analysis of six differential cross-section measurements of top-quark pair production in the dilepton channel from the ATLAS and CMS experiments. The data are compared to state-of-the-art QCD predictions with and without the inclusion of toponium formation effects. This contribution is modelled via a re-weighting of fixed-order matrix elements using the Green's function of the non-relativistic QCD Hamiltonian, and we employ a statistical model to quantify the preference of the data for the toponium hypothesis. All observables yield Bayes factors larger than unity, with two exceeding 20, yielding strong evidence for toponium formation in top-quark pair production at the LHC
Representations and characters of quantum affine algebras at the crossroads between cluster categorification and quantum integrable models
No full textInternational audienceIn this lecture, we survey a number of recent results and developments regarding the representation theory of infinite-dimensional quantum groups (quantum affine algebras and related algebras), as well as their connections with cluster categorification and quantum integrable models. We will also give new examples and conjectures
Single-cell exploration of gonadal somatic cell lineage specification during human sex determination
No full textInternational audienceGonad development is an exciting model to study cell fate commitment. A better understanding of sex determination requires the identification of all involved cell types and their dynamic expression programs. Here we present an atlas of 128,000 single cells from human gonads between 5 and 12 postconceptional weeks. A focused analysis of somatic cells uncovered a population of bipotential progenitors derived from the coelomic epithelium of both testes and ovaries, which may have the capacity to commit to either a steroidogenic or a supporting fate. Moreover, our analyses suggest that early supporting cells, prior to differentiation into Sertoli or pre-granulosa cells, also give rise to the rete testis/ovarii and that the ovary retains the capacity to feed the supporting cell pool for an extended period of time, directly from the surface epithelium. Finally, the potential involvement of the GnRH signaling pathway in regulating testis differentiation was assessed ex vivo
Grand-Canonical Symmetric Orbifold Theories
No full textInternational audienceIn this letter, we study grand-canonical symmetric orbifolds of conformal field theories on the sphere. We show that a consistent operator product expansion can be defined, provided the Hilbert space is taken to be the direct sum of symmetric orbifolds of all degrees. This Hilbert space contains a tower of central operators of conformal dimension zero, one of which represents the central charge of the Virasoro algebra. Our construction thus provides a conformal field theory interpretation of the central charge operator in string theory
1.8 per cent measurement of from Cepheids alone
No full textInternational audienceOne of the most pressing problems in current cosmology is the cause of the Hubble tension. We revisit a two-rung distance ladder, composed only of Cepheid periods and magnitudes, anchor distances in the Milky Way, Large Magellanic Cloud, NGC 4258, and host galaxy redshifts. We adopt the SH0ES data for the most up-to-date and carefully vetted measurements, where the Cepheid hosts were selected to harbour also Type Ia supernovae. We introduce two important improvements: a rigorous selection modelling and a state-of-the-art density and peculiar velocity model using Manticore-Local, based on the Bayesian Origin Reconstruction from Galaxies (BORG) algorithm. We infer , assuming the Cepheid host sample was selected by estimated supernova magnitudes. Less plausible selection criteria shift by about one standard deviation. The posterior has a lower central value and a 45 per cent smaller error than a previous study using the same data. The result is also slightly lower than the supernova-based SH0ES inferred value of , and is in tension with the latest standard cosmological model microwave background results. These results demonstrate that a measurement of of sufficient precision to weigh in on the Hubble tension is achievable using second-rung data alone, underscoring the importance of robust and accurate statistical modelling