Combining Gaia and GRAVITY: Characterising five new directly detected substellar companions

International audiencePrecise mass constraints are vital for the characterisation of brown dwarfs and exoplanets. Here we present how the combination of data obtained by Gaia and GRAVITY can help enlarge the sample of substellar companions with measured dynamical masses. We show how the Non-Single-Star (NSS) two-body orbit catalogue contained in Gaia DR3 can be used to inform high-angular-resolution follow-up observations with GRAVITY. Applying the method presented in this work to eight Gaia candidate systems, we detect all eight predicted companions, seven of which were previously unknown and five are of a substellar nature. Among the sample is Gaia DR3 2728129004119806464 B, which - detected at an angular separation of (34.01 ± 0.15) mas from the host - is the closest substellar companion ever imaged. In combination with the system's distance and the orbital elements, this translates to a semi-major axis of (0.938 ± 0.023) AU. WT 766 B, detected at a greater angular separation, was confirmed to be on an orbit exhibiting an even smaller semi-major axis of (0.676 ± 0.008) AU. The GRAVITY data were then used to break the host-companion mass degeneracy inherent to the Gaia NSS orbit solutions as well as to constrain the orbital solutions of the respective target systems. Knowledge of the companion masses enabled us to further characterise them in terms of their ages, effective temperatures, and radii via the application of evolutionary models. The inferred ages exhibit a distinct bias towards values younger than what is to be expected based on the literature. The results serve as an independent validation of the orbital solutions published in the NSS two-body orbit catalogue and show that the combination of astrometric survey missions and high-angular-resolution direct imaging holds great promise for efficiently increasing the sample of directly imaged companions in the future, especially in the light of Gaia's upcoming DR4 and the advent of GRAVITY+

De la crise économique à la crise politique : Podemos, une structure d’opportunités politiques

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A dTDP-L-Rhamnose 4-epimerase required for glycopeptidolipid biosynthesis in Mycobacterium abscessus

International audienceMycobacterium abscessus causes severe lung infections in cystic fibrosis patients and exhibits smooth (S) or rough (R) morphotypes. Disruption of glycopeptidolipid (GPL) production results in the S-to-R transition but the underlying molecular mechanisms of this transition remain incompletely understood. Herein, we characterized MAB_4111c in relation to GPL synthesis and investigated the effects of MAB_4111c deletion in M. abscessus pathogenicity. An enzymatic assay indicated that MAB_4111c, also designated Tle for Talose epimerase, is converting dTDP-L-Rhamnose into dTDP-6-deoxy-L-Talose. A tle deletion mutant was constructed in the S variant of M. abscessus and relative areas of Rhamnose and 6-deoxy-Talose and their methylated forms expressed as ratios of total monosaccharides, showed an altered GPL profile lacking 6-deoxy-Talose. Thus, Tle provides dTDP-6-deoxy-L-Talose, subsequently used by the glycosyltransferase Gtf1 to transfer 6-deoxy-Talose to the GPL backbone. Strikingly, the tle mutant exhibited a R morphotype, showed impaired sliding motility and biofilm formation, and these phenotypes were rescued upon functional complementation. Moreover, deletion of tle in M. abscessus results in increased pathogenicity and killing in zebrafish embryos. Together, our results underscore the importance of the dTDP-L-Rhamnose 4-epimerase activity in GPL biosynthesis and in influencing M. abscessus virulence

Fluxes in cities. How a crowd flows in the streets?

International audienceThe topic of the BIP "Overtourism in global cities. Impacts, challenges and solutions" seems far from common research topics in a physics or mechanics laboratory. However, there is a strong analogy between the motion of people, cars and buses for tourism and other physical motions such as flow of water or granular material. This short paper introduces common concepts which can be very useful for a geographical study of tourism.</div

Influence of the Jovian Current Sheet Models on the Mapping of the UV Auroral Footprints of Io, Europa, and Ganymede

International audienceThe in situ characterization of moon-magnetosphere interactions at Jupiter and the mapping of moon auroral footpaths require accurate global models of the magnetospheric magnetic field. In this study, we compare the ability of two widely-used current sheet models, Khurana-2005 (KK2005) and Connerney-2020 (CON2020) combined with the most recent internal magnetic field model of Jupiter (JRM33) to match representative Galileo and Juno measurements acquired at low, medium, and high latitudes. With the adjustments of the KK2005 model to JRM33, we show that in the outer and middle magnetosphere (R &gt; 15RJ), JRM33 + KK2005 is found to be the best model to reproduce the magnetic field observations of Galileo and Juno as it accounts for local time effects. JRM33 + CON2020 gives the most accurate representation of the inner magnetosphere. This finding is drawn from comparisons with Juno in situ magnetic field measurements and confirmed by contrasting the timing of the crossings of the Io, Europa, and Ganymede flux tubes identified in the Juno particles data with the two model estimates. JRM33 + CON2020 also maps more accurately the UV auroral footpath of Io, Europa, and Ganymede observed by Juno than JRM33 + KK2005. The JRM33 + KK2005 model predicts a local time asymmetry in position of the moons' footprints, which is however not detected in Juno's UV measurements. This could indicate that local time effects on the magnetic field are marginal at the orbital locations of Io, Europa, and Ganymede. Finally, the accuracy of the models and their predictions as a function of hemisphere, local time, and longitude is explored

Natural discrete differential calculus in physics

International audienceWe sharpen a recent observation by Tim Maudlin: differential calculus is a natural language for physics only if additional structure, like the definition of a Hodge dual or a metric, is given, but the discrete version of this calculus provides this additional structure for free

Moyal Planes are Spectral Triples

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KiDS-1000 cosmology: Combined second- and third-order shear statistics

International audienceThis paper performs the first cosmological parameter analysis of the KiDS-1000 data with second- and third-order shear statistics. This work builds on a series of papers that describe the roadmap to third-order shear statistics. We derive and test a combined model of the second-order shear statistic, namely the COSEBIs and the third-order aperture mass statistics $\langle M_\mathrm{ap}^3\rangle$ in a tomographic set-up. We validate our pipeline with $N$-body simulations that mock the fourth Kilo Degree survey data release. To model the second- and third-order statistics, we use the latest version of \textsc{HMcode2020} for the power spectrum and \textsc{BiHalofit} for the bispectrum. Furthermore, we use an analytic description to model intrinsic alignments and hydro-dynamical simulations to model the effect of baryonic feedback processes. Lastly, we decreased the dimension of the data vector significantly by considering for the $\langle M_\mathrm{ap}^3\rangle$ part of the data vector only equal smoothing radii, making a data analysis of the fourth Kilo Degree survey data release using a combined analysis of COSEBIs third-order shear statistic possible. We first validate the accuracy of our modelling by analysing a noise-free mock data vector assuming the KiDS-1000 error budget, finding a shift in the maximum-a-posterior of the matter density parameter $\Delta \Omega_m< 0.02\, \sigma_{\Omega_m}$ and of the structure growth parameter $\Delta S_8 < 0.05\, \sigma_{S_8}$. Lastly, we performed the first KiDS-1000 cosmological analysis using a combined analysis of second- and third-order shear statistics, where we constrained $\Omega_m=0.248^{+0.062}_{-0.055}$ and $S_8=\sigma_8\sqrt{\Omega_m/0.3}=0.772\pm0.022$. The geometric average on the errors of $\Omega_\mathrm{m}$ and $S_8$ of the combined statistics increased compared to the second-order statistic by 2.2

Broad Absorption Line Quasars in the Dark Energy Spectroscopic Instrument Early Data Release

International audienceBroad absorption line (BAL) quasars are characterized by gas clouds that absorb flux at the wavelength of common quasar spectral features, although blueshifted by velocities that can exceed 0.1c. BAL features are interesting as signatures of significant feedback, yet they can also compromise cosmological studies with quasars through their impact on accurate redshifts and measurements of the matter density distribution traced by the Lyman-alpha forest. The presence of BALs can also significantly contaminate the shape of the most prominent quasar emission lines and introduce systematic shifts in quasar redshifts. We present a catalog of BAL quasars discovered in the Dark Energy Spectroscopic Instrument (DESI) survey Early Data Release, which were observed as part of DESI Survey Validation, as well as the first two months of the main survey. We describe our method to automatically identify BAL quasars in DESI data, the quantities we measure for each BAL, and investigate the completeness and purity of this method with mock DESI observations. We mask the wavelengths of the BAL features and recompute the quasar redshifts, and find the new redshifts differ by 243 km/s on average for the BAL quasar sample. These new, more accurate redshifts are important to obtain the best measurements of quasar clustering, especially at small scales. Finally, we present some spectra of rarer classes of BALs that illustrate the potential of DESI data to identify such populations for further study

Liver disease in germline mutations of telomere-related genes: Prevalence, clinical, radiological, pathological features, outcome, and risk factors

International audienceBackground and aim: Germline mutations of telomere-related genes (TRG) induce multiorgan dysfunction, and liver-specific manifestations have not been clearly outlined. We aimed to describe TRG mutations-associated liver diseases. Approach and results: Retrospective multicentre analysis of liver disease (transaminases&gt;30 IU/L and/or abnormal liver imaging) in patients with TRG mutations. Main measurements were characteristics, outcomes, and risk factors of liver disease in a TRG mutations cohort. The prevalence of liver disease was compared to a community-based control group (n=1190) stratified for age and matched 1:3 for known risk factors of liver disease. Among 132 patients with TRG mutations, 95 (72%) had liver disease, with associated lung, blood, skin, rheumatological and ophthalmological TRG diseases in 82%, 77%, 55%, 39%, and 30% of cases, respectively. Liver biopsy was performed in 52/95 patients, identifying porto-sinusoidal vascular disease (PSVD) in 48%, and advanced fibrosis/cirrhosis in 15%. After a follow-up of 21 months (12-54), ascites, hepato-pulmonary syndrome, variceal bleeding, and hepatocellular carcinoma occurred in 14%, 13%, 13%, and 2% of cases, respectively. Five-year liver transplantation-free survival was 69%. A FIB-4 score ≥3·25 and ≥1 risk factor for cirrhosis were associated with poor liver transplantation-free survival. Liver disease was more frequent in patients with TRG mutations than in the paired control group (80/396, (20%)), OR 12.9 (CI95% 7.8-21.3, p &lt;0.001). Conclusions: TRG mutations significantly increase the risk of developing liver disease. Although symptoms may be mild they may be associated with severe disease. PSVD and cirrhosis were the most frequent lesions suggesting that the mechanism of action is multifactorial