73 research outputs found
43 â CaractĂ©ristiques et prise en charge des cancers du sein pT1a,bN0M0 en France : la cohorte ODISSEE
Planck 2015 results. XXVII. The Second Planck Catalogue of Sunyaev-Zeldovich Sources
We present the all-sky Planck catalogue of Sunyaev-Zeldovich (SZ) sources detected from the 29 month full-mission data. The catalogue (PSZ2) is the largest SZ-selected sample of galaxy clusters yet produced and the deepest all-sky catalogue of galaxy clusters. It contains 1653 detections, of which 1203 are confirmed clusters with identified counterparts in external data-sets, and is the first SZ-selected cluster survey containing > confirmed clusters. We present a detailed analysis of the survey selection function in terms of its completeness and statistical reliability, placing a lower limit of 83% on the purity. Using simulations, we find that the Y5R500 estimates are robust to pressure-profile variation and beam systematics, but accurate conversion to Y500 requires. the use of prior information on the cluster extent. We describe the multi-wavelength search for counterparts in ancillary data, which makes use of radio, microwave, infra-red, optical and X-ray data-sets, and which places emphasis on the robustness of the counterpart match. We discuss the physical properties of the new sample and identify a population of low-redshift X-ray under- luminous clusters revealed by SZ selection. These objects appear in optical and SZ surveys with consistent properties for their mass, but are almost absent from ROSAT X-ray selected samples
Planck intermediate results. VIII. Filaments between interacting clusters
About half of the baryons of the Universe are expected to be in the form of
filaments of hot and low density intergalactic medium. Most of these baryons
remain undetected even by the most advanced X-ray observatories which are
limited in sensitivity to the diffuse low density medium. The Planck satellite
has provided hundreds of detections of the hot gas in clusters of galaxies via
the thermal Sunyaev-Zel'dovich (tSZ) effect and is an ideal instrument for
studying extended low density media through the tSZ effect. In this paper we
use the Planck data to search for signatures of a fraction of these missing
baryons between pairs of galaxy clusters. Cluster pairs are good candidates for
searching for the hotter and denser phase of the intergalactic medium (which is
more easily observed through the SZ effect). Using an X-ray catalogue of
clusters and the Planck data, we select physical pairs of clusters as
candidates. Using the Planck data we construct a local map of the tSZ effect
centered on each pair of galaxy clusters. ROSAT data is used to construct X-ray
maps of these pairs. After having modelled and subtracted the tSZ effect and
X-ray emission for each cluster in the pair we study the residuals on both the
SZ and X-ray maps. For the merging cluster pair A399-A401 we observe a
significant tSZ effect signal in the intercluster region beyond the virial
radii of the clusters. A joint X-ray SZ analysis allows us to constrain the
temperature and density of this intercluster medium. We obtain a temperature of
kT = 7.1 +- 0.9, keV (consistent with previous estimates) and a baryon density
of (3.7 +- 0.2)x10^-4, cm^-3. The Planck satellite mission has provided the
first SZ detection of the hot and diffuse intercluster gas.Comment: Accepted by A&
Planck intermediate results: IV. the XMM-Newton validation programme for new Planck galaxy clusters
Planck intermediate results: III. the relation between galaxy cluster mass and Sunyaev-Zeldovich signal
We examine the relation between the galaxy cluster mass M and Sunyaev-Zeldovich (SZ) effect signal DA2 Y500 for a sample of 19 objects for which weak lensing (WL) mass measurements obtained from Subaru Telescope data are available in the literature. Hydrostatic X-ray masses are derived from XMM-Newton archive data, and the SZ effect signal is measured from Planck all-sky survey data. We find an MWL-D A2 Y500 relation that is consistent in slope and normalisation with previous determinations using weak lensing masses; however, there is a normalisation offset with respect to previous measures based on hydrostatic X-ray mass-proxy relations. We verify that our SZ effect measurements are in excellent agreement with previous determinations from Planck data. For the present sample, the hydrostatic X-ray masses at R500 are on average ~ 20 percent larger than the corresponding weak lensing masses, which is contrary to expectations. We show that the mass discrepancy is driven by a difference in mass concentration as measured by the two methods and, for the present sample, that the mass discrepancy and difference in mass concentration are especially large for disturbed systems. The mass discrepancy is also linked to the offset in centres used by the X-ray and weak lensing analyses, which again is most important in disturbed systems. We outline several approaches that are needed to help achieve convergence in cluster mass measurement with X-ray and weak lensing observations. © ESO, 2013
Planck early results. IX. XMM-Newton follow-up for validation of Planck cluster candidates
We present the XMM-Newton follow-up for confirmation of Planck cluster candidates. Twenty-five candidates have been observed to date using
snapshot (âŒ10 ks) exposures, ten as part of a pilot programme to sample a low range of signal-to-noise ratios (4 < S/N < 6), and a further 15 in a
programme to observe a sample of S/N > 5 candidates. The sensitivity and spatial resolution of XMM-Newton allows unambiguous discrimination
between clusters and false candidates. The 4 false candidates have S/N †4.1. A total of 21 candidates are confirmed as extended X-ray sources.
Seventeen are single clusters, the majority of which are found to have highly irregular and disturbed morphologies (about âŒ70%). The remaining
four sources are multiple systems, including the unexpected discovery of a supercluster at z = 0.45. For 20 sources we are able to derive a redshift
estimate from the X-ray Fe K line (albeit of variable quality). The new clusters span the redshift range 0.09 <⌠z <⌠0.54, with a median redshift
of z ⌠0.37. A first determination is made of their X-ray properties including the characteristic size, which is used to improve the estimate of
the SZ Compton parameter, Y500. The follow-up validation programme has helped to optimise the Planck candidate selection process. It has also
provided a preview of the X-ray properties of these newly-discovered clusters, allowing comparison with their SZ properties, and to the X-ray
and SZ properties of known clusters observed in the Planck survey. Our results suggest that Planck may have started to reveal a non-negligible
population of massive dynamically perturbed objects that is under-represented in X-ray surveys. However, despite their particular properties, these
new clusters appear to follow the Y500âYX relation established for X-ray selected objects, where YX is the product of the gas mass and temperature
Planck intermediate results V : Pressure profiles of galaxy clusters from the Sunyaev-Zeldovich effect
This article has an erratum: http://dx.doi.org/10.1051/0004-6361/201220040ePeer reviewe
Planck Early Results. VII. The Early Release Compact Source Catalogue
A brief description of the methodology of construction, contents and usage of the Planck Early Release Compact Source Catalogue (ERCSC),
including the Early Cold Cores (ECC) and the Early Sunyaev-Zeldovich (ESZ) cluster catalogue is provided. The catalogue is based on data that
consist of mapping the entire sky once and 60% of the sky a second time by Planck, thereby comprising the first high sensitivity radio/submillimetre
observations of the entire sky. Four source detection algorithms were run as part of the ERCSC pipeline. A Monte-Carlo algorithm based on the
injection and extraction of artificial sources into the Planck maps was implemented to select reliable sources among all extracted candidates such
that the cumulative reliability of the catalogue is â„90%. There is no requirement on completeness for the ERCSC. As a result of the Monte-Carlo
assessment of reliability of sources from the different techniques, an implementation of the PowellSnakes source extraction technique was used
at the five frequencies between 30 and 143 GHz while the SExtractor technique was used between 217 and 857GHz. The 10Ï photometric flux
density limit of the catalogue at |b| > 30⊠is 0.49, 1.0, 0.67, 0.5, 0.33, 0.28, 0.25, 0.47 and 0.82 Jy at each of the nine frequencies between 30
and 857 GHz. Sources which are up to a factor of âŒ2 fainter than this limit, and which are present in âcleanâ regions of the Galaxy where the sky
background due to emission from the interstellar medium is low, are included in the ERCSC if they meet the high reliability criterion. The Planck
ERCSC sources have known associations to stars with dust shells, stellar cores, radio galaxies, blazars, infrared luminous galaxies and Galactic
interstellar medium features. A significant fraction of unclassified sources are also present in the catalogs. In addition, two early release catalogs
that contain 915 cold molecular cloud core candidates and 189 SZ cluster candidates that have been generated using multifrequency algorithms are
presented. The entire source list, with more than 15000 unique sources, is ripe for follow-up characterisation with Herschel, ATCA, VLA, SOFIA,
ALMA and other ground-based observing facilities
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