59 research outputs found
Planck Intermediate Results II: Comparison of SunyaevâZeldovich measurements from Planck and from the Arcminute Microkelvin Imager for 11 galaxy clusters
A comparison is presented of SunyaevâZeldovich measurements for 11 galaxy clusters as obtained by Planck and by the ground-based interferom- eter, the Arcminute Microkelvin Imager. Assuming a universal spherically-symmetric Generalised Navarro, Frenk & White (GNFW) model for the cluster gas pressure profile, we jointly constrain the integrated Compton-Y parameter (Y500) and the scale radius (Ξ500) of each cluster. Our resulting constraints in the Y500 â Ξ500 2D parameter space derived from the two instruments overlap significantly for eight of the clusters, although, overall, there is a tendency for AMI to find the SunyaevâZeldovich signal to be smaller in angular size and fainter than Planck. Significant discrepancies exist for the three remaining clusters in the sample, namely A1413, A1914, and the newly-discovered Planck cluster PLCKESZ G139.59+24.18. The robustness of the analysis of both the Planck and AMI data is demonstrated through the use of detailed simulations, which also discount confusion from residual point (radio) sources and from diffuse astrophysical foregrounds as possible explanations for the discrepancies found. For a subset of our cluster sample, we have investigated the dependence of our results on the assumed pressure profile by repeating the analysis adopting the best-fitting GNFW profile shape which best matches X-ray observations. Adopting the best-fitting profile shape from the X-ray data does not, in general, resolve the discrepancies found in this subset of five clusters. Though based on a small sample, our results suggest that the adopted GNFW model may not be sufficiently flexible to describe clusters universally
Urinary, Circulating, and Tissue Biomonitoring Studies Indicate Widespread Exposure to Bisphenol A
Gamma-ray astronomy with ARGO-YBJ
ARGO-YBJ is a full coverage air shower array located at the YangBaJing Cosmic
Ray Laboratory (Tibet, P.R. China, 4300 m a.s.l., 606 g/cm2) recording data with a duty
cycle â„85% and an energy threshold of a few hundred GeV. In this paper the latest results
in Gamma-Ray Astronomy are summarized
Gamma-ray astronomy and cosmic-ray physics with ARGO-YBJ
The ARGO-YBJ detector, located 4300 m a.s.l. on the Tibet plateau, is a ground-based, full-
coverage array of Resistive Plate Chambers (RPCs) covering a surface of 78Ă74 m2, surrounded
by a guard ring of RPCs enclosing a total surface of about 11000 m2. ARGO-YBJ was designed
to detect extensive air showers generated by cosmic rays and gamma rays with primary energy
greater than few hundred GeV, in order to study the region of the cosmic-ray spectrum out of the
reach of both satellite-based experiments and traditional ground-based arrays. The experiment has
been running with its complete layout since November 2007, collecting over 2:5Ă1011 events.
The main results obtained by ARGO-YBJ will be presented here, and specifically: the monitoring
of astronomical gamma-ray sources, such as the Crab nebula and the MRK 421 AGN, the moon
shadow, the medium-scale anisotropy map, the proton-proton inelastic cross section at center-of-
mass energy between 70 and 500 GeV where no accelerator data are available
A Fault-Tolerant Method for Enhancing Reliability of Services Composition Application in WSNs Based on BPEL
Mechanical behavior and analysis of composite bridges with corrugated steel webs: State-of-the-art
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