The XXL Survey VIII: MUSE characterisation of intracluster light in a z∼\sim0.53 cluster of galaxies

Within a cluster, gravitational effects can lead to the removal of stars from their parent galaxies. Gas hydrodynamical effects can additionally strip gas and dust from galaxies. The properties of the ICL can therefore help constrain the physical processes at work in clusters by serving as a fossil record of the interaction history. The present study is designed to characterise this ICL in a ~10^14 M_odot and z~0.53 cluster of galaxies from imaging and spectroscopic points of view. By applying a wavelet-based method to CFHT Megacam and WIRCAM images, we detect significant quantities of diffuse light. These sources were then spectroscopically characterised with MUSE. MUSE data were also used to compute redshifts of 24 cluster galaxies and search for cluster substructures. An atypically large amount of ICL has been detected in this cluster. Part of the detected diffuse light has a very weak optical stellar component and apparently consists mainly of gas emission, while other diffuse light sources are clearly dominated by old stars. Furthermore, emission lines were detected in several places of diffuse light. Our spectral analysis shows that this emission likely originates from low-excitation parameter gas. The stellar contribution to the ICL is about 2.3x10^9 yrs old even though the ICL is not currently forming a large number of stars. On the other hand, the contribution of the gas emission to the ICL in the optical is much greater than the stellar contribution in some regions, but the gas density is likely too low to form stars. These observations favour ram pressure stripping, turbulent viscous stripping, or supernovae winds as the origin of the large amount of intracluster light. Since the cluster appears not to be in a major merging phase, we conclude that ram pressure stripping is the most plausible process that generates the observed ICL sources.Comment: Accepted in A&A, english enhanced, figure location different than in the A&A version due to different style files, shortened abstrac

Cardiac protective effects of Moringa oleifera seeds in spontaneous hypertensive rats

BACKGROUND Hypertension is characterized by a maintained high blood pressure leading to cardiac complications such as left ventricular hypertrophy and fibrosis and an increased risk of heart failure and myocardial infarction. This study investigated the cardiac effects of oral administration of Moringa oleifera (MOI) seed powder in spontaneous hypertensive rats (SHR). METHODS SHR received food containing MOI seed powder (750mg/d, 8 weeks) or normal food. In vivo measurement of hemodynamic parameters by telemetry and cardiac structure and function analysis by echocardiography were performed. Histological studies were performed to determine fibrosis and protein expression. RESULTS MOI treatment did not modify blood pressure in SHR but reduced nocturnal heart rate and improved cardiac diastolic function (reduction of isovolumetric relaxation time and deceleration time of the E wave, increase of ejection volume and cardiac output compared to nontreated SHR). Left ventricular anterior wall thickness, interseptal thickness on diastole, and relative wall thickness were reduced after MOI treatment. Furthermore, we found a significant reduction of fibrosis in the left ventricle of MOI-treated SHR. This antihypertrophic and antifibrotic effect of MOI was associated with increased expression of peroxisome proliferator-activated receptor (PPAR)-α and δ, reduced cardiac triglyceride level, and enhanced plasmatic prostacyclins. CONCLUSIONS Our data show a beneficial effect of MOI on the cardiac structure and function in SHR associated with an upregulation of PPAR-α and δ signaling. This study thus provides scientific rational support for the empirical use of MOI in the traditional Malagasy medicine against cardiac diseases associated with blood pressure overload

The XXL Survey: XII. Optical spectroscopy of X-ray-selected clusters and the frequency of AGN in superclusters

This article belongs to the first series of XXL publications. It presents multifibre spectroscopic observations of three 0.55 sq.deg. fields in the XXL Survey, which were selected on the basis of their high density of X-ray-detected clusters. The observations were obtained with the AutoFib2+WYFFOS (AF2) wide-field fibre spectrograph mounted on the 4.2m William Herschel Telescope. The paper first describes the scientific rationale, the preparation, the data reduction, and the results of the observations, and then presents a study of active galactic nuclei (AGN) within three superclusters. We obtained redshifts for 455 galaxies in total, 56 of which are counterparts of X-ray point-like sources. We were able to determine the redshift of the merging supercluster XLSSC-e, which consists of six individual clusters at z~0.43, and we confirmed the redshift of supercluster XLSSC-d at z~0.3. More importantly, we discovered a new supercluster, XLSSC-f, that comprises three galaxy clusters also at z~0.3. We find a significant 2D overdensity of X-ray point-like sources only around the supercluster XLSSC-f. This result is also supported by the spatial (3D) analysis of XLSSC-f, where we find four AGN with compatible spectroscopic redshifts and possibly one more with compatible photometric redshift. In addition, we find two AGN (3D analysis) at the redshift of XLSSC-e, but no AGN in XLSSC-d. Comparing these findings with the optical galaxy overdensity we conclude that the total number of AGN in the area of the three superclusters significantly exceeds the field expectations. The difference in the AGN frequency between the three superclusters cannot be explained by the present study because of small number statistics. Further analysis of a larger number of superclusters within the 50 sq. deg. of the XXL is needed before any conclusions on the effect of the supercluster environment on AGN can be reached.Comment: 11 pages, published by A&

AMPK alpha 1-induced RhoA phosphorylation mediates vasoprotective effect of estradiol

OBJECTIVE: Estradiol (E2) mediates numerous beneficial effects assigned to estrogens, but whereas mechanisms have been described at the endothelial level, direct effects on vascular smooth muscle cells (VSMC) are poorly documented. As evidence accumulates regarding the role of RhoA in vascular pathophysiology and the benefit of RhoA-Rho associated protein kinase (Rock) pathway inhibition, we analyzed if E2 could inhibit it in VSMC. METHODS AND RESULTS: We show that in VSMC, E2 inhibits the RhoA-Rock pathway in a time- and concentration-dependent manner. The inhibition of RhoA-Rock pathway results from E2-induced phosphorylation of the Ser188 of RhoA. Using pharmacological, transfection, and in vitro phosphorylation experiments, we demonstrate that AMP-activated protein kinase subunit alpha 1 (AMPKalpha1) is activated by estrogen receptor stimulation and catalyzes RhoA phosphorylation induced by E2. Ex vivo, ovariectomy leads to an increase in the amplitude of phenylephrine- or serotonine-induced contractions of aortic rings in wild-type mice but not in AMPKalpha1-knock-out mice or E2-supplemented animals. These functional effects were correlated with a reduced level of RhoA phosphorylation in the aorta of ovariectomized female, male, and AMPKalpha1 knock-out mice. CONCLUSION: Our work thus defines AMPKalpha1 as (1) a new kinase for RhoA and (2) a new mediator of the vasoprotective effects of estrogen

The Spitzer-South Pole Telescope Deep Field: Survey Design and IRAC Catalogs

The Spitzer-South Pole Telescope Deep Field (SSDF) is a wide-area survey using Spitzer's Infrared Array Camera (IRAC) to cover 94 square degrees of extragalactic sky, making it the largest IRAC survey completed to date outside the Milky Way midplane. The SSDF is centered at 23:30,-55:00, in a region that combines observations spanning a broad wavelength range from numerous facilities. These include millimeter imaging from the South Pole Telescope, far-infrared observations from Herschel/SPIRE, X-ray observations from the XMM XXL survey, near-infrared observations from the VISTA Hemisphere Survey, and radio-wavelength imaging from the Australia Telescope Compact Array, in a panchromatic project designed to address major outstanding questions surrounding galaxy clusters and the baryon budget. Here we describe the Spitzer/IRAC observations of the SSDF, including the survey design, observations, processing, source extraction, and publicly available data products. In particular, we present two band-merged catalogs, one for each of the two warm IRAC selection bands. They contain roughly 5.5 and 3.7 million distinct sources, the vast majority of which are galaxies, down to the SSDF 5-sigma sensitivity limits of 19.0 and 18.2 Vega mag (7.0 and 9.4 microJy) at 3.6 and 4.5 microns, respectively.Comment: Accepted by ApJS; this version updated to conform to refereed articl

The 2-10 keV unabsorbed luminosity function of AGN from the XMM-Newton LSS, CDFS and COSMOS surveys

The XMM-LSS, XMM-COSMOS, and XMM-CDFS surveys are complementary in terms of sky coverage and depth. Together, they form a clean sample with the least possible variance in instrument effective areas and PSF. Therefore this is one of the best samples available to determine the 2-10 keV luminosity function of AGN and its evolution. The samples and the relevant corrections for incompleteness are described. A total of 2887 AGN is used to build the LF in the luminosity interval 10^42-10^46 erg/s, and in the redshift interval 0.001-4. A new method to correct for absorption by considering the probability distribution for the column density conditioned on the hardness ratio is presented. The binned luminosity function and its evolution is determined with a variant of the Page-Carrera method, improved to include corrections for absorption and to account for the full probability distribution of photometric redshifts. Parametric models, namely a double power-law with LADE or LDDE evolution, are explored using Bayesian inference. We introduce the Watanabe-Akaike information criterion (WAIC) to compare the models and estimate their predictive power. Our data are best described by the LADE model, as hinted by the WAIC indicator. We also explore the 15-parameter extended LDDE model recently proposed by Ueda et al., and find that this extension is not supported by our data. The strength of our method is that it provides: un-absorbed non-parametric estimates; credible intervals for luminosity function parameters; model choice according to which one has more predictive power for future data.Comment: In press on A&A. The revised version corrects typos and the LF normalisations in tables 1,2,5 and figs.9-12, which were on an incorrect scale. Online material available at http://www.astro.lu.se/~piero/xlf/xlf-paper-tables2.tgz . The software is available on the author's website http://www.astro.lu.se/~piero/LFTools/index.html and on github: https://github.com/piero-ranalli/LFTool

Effect of the microstructure on the cutting performance of superhard (Ti, Si, Al)N nanocomposite films

A d.c. reactive magnetron sputtering technique was used to deposit (Ti,Si,Al)N coatings onto WC–Co cutting tools. The microstructure of the coatings was analysed using X-ray diffraction (XRD) and highresolution transmission electron microscopy (HRTEM) measurement. Before the cutting experiments, the XRD results revealed a structure indexed to an fcc TiN. The results obtained by the XRD tests, with detector variation in asymmetric mode (rocking curves) showed a decrease in the quality of the fiber texture in the (111) grains with the change on deposition chamber geometry (two magnetrons in place of four magnetrons). Cross-sectional HRTEM images of the (Ti,Al)N sample showed grains with a diameter between 16 and 30 nm, while for the (Ti,Si,Al)N samples grains with a diameter between 6 and 10 nm were observed. Furthermore, through the visualization of bright field images it was possible to discern a columnar structure. For samples prepared at high deposition rates (2 mm/h), HRTEM micrographs revealed the formation of the multilayer stacking of (Ti,Si)N/(Ti,Al)N