443 research outputs found
The XMM-LSS survey: the Class 1 cluster sample over the extended 11 deg and its spatial distribution
This paper presents 52 X-ray bright galaxy clusters selected within the 11
deg XMM-LSS survey. 51 of them have spectroscopic redshifts
(), one is identified at , and all together make
the high-purity "Class 1" (C1) cluster sample of the XMM-LSS, the highest
density sample of X-ray selected clusters with a monitored selection function.
Their X-ray fluxes, averaged gas temperatures (median keV),
luminosities (median ergs/s) and total mass
estimates (median ) are measured, adapting to
the specific signal-to-noise regime of XMM-LSS observations. The redshift
distribution of clusters shows a deficit of sources when compared to the
cosmological expectations, regardless of whether WMAP-9 or Planck-2013 CMB
parameters are assumed. This lack of sources is particularly noticeable at . However, after quantifying uncertainties due to small
number statistics and sample variance we are not able to put firm (i.e. ) constraints on the presence of a large void in the cluster
distribution. We work out alternative hypotheses and demonstrate that a
negative redshift evolution in the normalization of the relation
(with respect to a self-similar evolution) is a plausible explanation for the
observed deficit. We confirm this evolutionary trend by directly studying how
C1 clusters populate the space, properly accounting for selection
biases. We point out that a systematically evolving, unresolved, central
component in clusters and groups (AGN contamination or cool core) can impact
the classification as extended sources and be partly responsible for the
observed redshift distribution.[abridged]Comment: 33 pages, 21 figures, 3 tables ; accepted for publication in MNRA
The XXL Survey VIII: MUSE characterisation of intracluster light in a z0.53 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
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&
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
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
Diabetes-Related Antibody-Testing is a Valuable Screening Tool for Identifying Monogenic Diabetes – A Survey from the Worldwide SWEET Registry
Aims: To evaluate access to screening tools for monogenic diabetes in paediatric diabetes centres across the world and its impact on diagnosis and clinical outcomes of children and youth with genetic forms of diabetes.
Methods: 79 centres from the SWEET diabetes registry including 53,207 children with diabetes participated in a survey on accessibility and use of diabetes related antibodies, c-peptide and genetic testing.
Results: 73, 63 and 62 participating centres had access to c-peptide, antibody and genetic testing, respectively. Access to antibody testing was associated with higher proportion of patients with rare forms of diabetes identified with monogenic diabetes (54 % versus 17 %, p = 0.01), lower average whole clinic HbA1c (7.7[Q1,Q2: 7.3-8.0]%/61[56-64]mmol/mol versus 9.2[8.6-10.0]%/77[70-86]mmol/mol, p < 0.001) and younger age at onset (8.3 [7.3-8.8] versus 9.7 [8.6-12.7] years p < 0.001). Additional access to c-peptide or genetic testing was not related to differences in age at onset or HbA1c outcome.
Conclusions: Clinical suspicion and antibody testing are related to identification of different types of diabetes. Implementing access to comprehensive antibody screening may provide important information for selecting individuals for further genetic evaluation. In addition, worse overall clinical outcomes in centers with limited diagnostic capabilities indicate they may also need support for individualized diabetes management.info:eu-repo/semantics/publishedVersio
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