The X-CLASS - redMaPPer galaxy cluster comparison: I. Identification procedures

We performed a detailed and, for a large part interactive, analysis of the matching output between the X-CLASS and redMaPPer cluster catalogues. The overlap between the two catalogues has been accurately determined and possible cluster positional errors were manually recovered. The final samples comprise 270 and 355 redMaPPer and X-CLASS clusters respectively. X-ray cluster matching rates were analysed as a function of optical richness. In a second step, the redMaPPer clusters were correlated with the entire X-ray catalogue, containing point and uncharacterised sources (down to a few 10^{-15} erg s^{-1} cm^{-2} in the [0.5-2] keV band). A stacking analysis was performed for the remaining undetected optical clusters. Main results show that neither of the wavebands misses any massive cluster (as coded by X-ray luminosity or optical richness). After correcting for obvious pipeline short-comings (about 10% of the cases both in optical and X-ray), ~50% of the redMaPPer (down to a richness of 20) are found to coincide with an X-CLASS cluster; when considering X-ray sources of any type, this fraction increases to ~ 80%; for the remaining objects, the stacking analysis finds a weak signal within 0.5 Mpc around the cluster optical centers. The fraction of clusters totally dominated by AGN-type emission appears to be of the order of a few percent. Conversely ~ 40% of the X-CLASS clusters are identified with a redMaPPer (down to a richness of 20) - part of the non-matches being due to the fact that the X-CLASS sample extends further out than redMaPPer (z<1 vs z<0.6); extending the correlation down to a richness of 5, raises the matching rate to ~ 65%.Comment: 15 pages, 20 figures, 2 table

Co-production of MCR-1 and extended-spectrum β-lactamase in Escherichia coli recovered from urinary tract infections in Switzerland

International audienc

Circadian variation in the circumstances of delivery in a population at low obstetric risk

While circadian variations in birth and perinatal mortality rates have previously been described in the literature, the reasons behind these observed rhythms remain unclear. The principal hypothetical causes include variations in obstetric practices and an association between the time of birth and biological parameters. In order to explore this issue we analysed the distribution patterns for time and day of birth, as well as circadian variations in maternal characteristics, obstetric practices and neonatal risk in a population at low obstetric risk. The study population included 685 low-risk pregnant women consecutively admitted at an early stage of labour to six maternity units. The results showed hourly variations in the birth rate and circadian variations in obstetric practices that might explain the hourly pattern observed for the birth rate. By contrast, the frequency of a positive neonatal risk indicator was uniform across all time categories in this population at low obstetric ris

The XXL Survey V: Detection of the Sunyaev-Zel'dovich effect of the Redshift 1.9 Galaxy Cluster XLSSU J021744.1-034536 with CARMA

We report the detection of the Sunyaev-Zel'dovich (SZ) effect of galaxy cluster XLSSU J021744.1-034536, using 30 GHz CARMA data. This cluster was discovered via its extended X-ray emission in the XMM-Newton Large Scale Structure survey, the precursor to the XXL survey. It has a photometrically determined redshift $z=1.91^{+0.19}_{-0.21}$, making it among the most distant clusters known, and nominally the most distant for which the SZ effect has been measured. The spherically integrated Comptonization is $Y_{500}=(3.0\pm0.4)\times 10^{-12}$, a measurement which is relatively insensitive to assumptions regarding the size and redshift of the cluster, as well as the background cosmology. Using a variety of locally calibrated cluster scaling relations extrapolated to z~2, we estimate a mass $M_{500} \sim (1$-$2)\times 10^{14}M_{sun}$ from the X-ray flux and SZ signal. The measured properties of this cluster are in good agreement with the extrapolation of an X-ray luminosity-SZ effect scaling relation calibrated from clusters discovered by the South Pole Telescope at higher masses and lower redshifts. The full XXL-CARMA sample will provide a more complete, multi-wavelength census of distant clusters in order to robustly extend the calibration of cluster scaling relations to these high redshifts.Comment: ApJ, in press. 9 pages, 4 figures, 4 table

Dynamical properties and detectability of the magneto-thermal instability in the intracluster medium

Context. Amongst many plasma processes potentially relevant to the dynamics of the intracluster medium (ICM), turbulence driven at observable scales by internal magnetised buoyancy instabilities like the magneto-thermal instability (MTI) stand out in the ICM outskirt, where the background temperature decreases with radius. Aims. We characterise the statistical properties of MTI turbulence and assess whether such magnetised dynamics would be detectable with the future X-ray calorimeter X-IFU onboard ATHENA. Methods. We make use of scaling laws derived by Perrone & Latter (2022a,b) to estimate the observable turbulent saturation levels and injection length of MTI turbulence for different ICM thermodynamic profiles, and perform a numerical MHD simulation of the dynamics with Braginskii heat and momentum diffusion. As a prospective exercise, we use the simulation to virtually observe MTI turbulence through the X-IFU. Results. In bright enough regions amenable to X-ray observations, the MTI drives mild turbulence up to $\sim$ 5% and $\sim$ 100 km/s (rms temperature fluctuation and velocity). However, the measurable integrated temperature fluctuation and line-of-sight velocity fields, which is essentially the azimuthal velocity component in cluster haloes, hardly exceed 1% and 10 km/s respectively. We show that such moderate signals would be hard to detect with upcoming X-ray telescopes. MTI turbulence is anisotropic in the direction of the gravity. If the fluctuation intensities were to be stronger than the current theoretical estimates, MTI fluctuations may be detectable and their anisotropy discernible with the X-IFU. Conclusions. Finding direct signatures of magnetised dynamics in the ICM, even at observable scales typical of the MTI, remains challenging. This study is a first step in this direction. Several numerical and observational strategies are discussed to make further progress.Comment: 20 pages, 13 figures, submitted to A&

Assessing the effect of tandem phase Sentinel-3 OLCI Sensor uncertainty on the estimation of potential ocean chlorophyll-a trends

The Sentinel-3 tandem project represents the first time that two ocean colour satellites have been flown in the same orbit with minimal temporal separation (~30 s), thus allowing them to have virtually identical views of the ocean. This offers an opportunity for understanding how differences in individual sensor uncertainty can affect conclusions drawn from the data. Here, we specifically focus on trend estimation. Observational chlorophyll-a uncertainty is assessed from the Sentinel-3A Ocean and Land Colour Imager (OLCI-A) and Sentinel-3B OLCI (OLCI-B) sensors using a bootstrapping approach. Realistic trends are then imposed on a synthetic chlorophyll-a time series to understand how sensor uncertainty could affect potential long-term trends in Sentinel-3 OLCI data. We find that OLCI-A and OLCI-B both show very similar trends, with the OLCI-B trend estimates tending to have a slightly wider distribution, although not statistically different from the OLCI-A distribution. The spatial pattern of trend estimates is also assessed, showing that the probability distributions of trend estimates in OLCI-A and OLCI-B are most similar in open ocean regions, and least similar in coastal regions and at high northern latitudes. This analysis shows that the two sensors should provide consistent trends between the two satellites, provided future ageing is well quantified and mitigated. The Sentinel-3 programme offers a strong baseline for estimating long-term chlorophyll-a trends by offering a series of satellites (starting with Sentinel-3A and Sentinel-3B) that use the same sensor design, reducing potential issues with cross-calibration between sensors. This analysis contributes an important understanding of the reliability of the two current Sentinel-3 OLCI sensors for future studies of climate change driven chlorophyll-a trends

Investigating the turbulent hot gas in X-COP galaxy clusters

Turbulent processes at work in the intracluster medium perturb this environment, displacing gas, and creating local density fluctuations that can be quantified via X-ray surface brightness fluctuation analyses. Improved knowledge of these phenomena would allow for a better determination of the mass of galaxy clusters, as well as a better understanding of their dynamic assembly. In this work, we aim to set constraints on the structure of turbulence using X-ray surface brightness fluctuations. We seek to consider the stochastic nature of this observable and to constrain the structure of the underlying power spectrum. We propose a new Bayesian approach, relying on simulation-based inference to account for the whole error budget. We used the X-COP cluster sample to individually constrain the power spectrum in four regions and within $R_{500}$. We spread the analysis on the 12 systems to alleviate the sample variance. We then interpreted the density fluctuations as the result of either gas clumping or turbulence. For each cluster considered individually, the normalisation of density fluctuations correlates positively with the Zernike moment and centroid shift, but negatively with the concentration and the Gini coefficient. The spectral index within $R_{500}$ and evaluated over all clusters is consistent with a Kolmogorov cascade. The normalisation of density fluctuations, when interpreted in terms of clumping, is consistent within $0.5 R_{500}$ with the literature results and numerical simulations; however, it is higher between 0.5 and $1 R_{500}$. Conversely, when interpreted on the basis of turbulence, we deduce a non-thermal pressure profile that is lower than the predictions of the simulations within 0.5 $R_{500}$, but still in agreement in the outer regions. We explain these results by the presence of central structural residues that are remnants of the dynamic assembly of the clusters.Comment: Accepted for publication in A&A. Abstract slightly abridged for arXi

La construction d'une communauté de sécurité en Europe : le cas des pays nordiques

Dans les pays européens, la sécurité intérieure est du ressort de différents types de police. C'est un legs de l'histoire et des traditions de chacun des Etats mais ce legs aura incontestablement des répercussions lorsqu'il s'agira de traiter, plus avant, de la sécurité à l'échelle de l'Europe. Au plan militaire, l'Europe se dote progressivement de capacités qui devraient répondre, à terme, à l'ensemble des missions dites de Petersberg à savoir : les missions d'action humanitaire et d'évacua..