Supermodel Analysis of the Hard X-Ray Excess in the Coma Cluster

The Supermodel provides an accurate description of the thermal contribution by the hot intracluster plasma which is crucial for the analysis of the hard excess. In this paper the thermal emissivity in the Coma cluster is derived starting from the intracluster gas temperature and density profiles obtained by the Supermodel analysis of X-ray observables: the XMM-Newton temperature profile and the Rosat brightness distribution. The Supermodel analysis of the BeppoSAX/PDS hard X-ray spectrum confirms our previous results, namely an excess at the c.l. of ~4.8sigma and a nonthermal flux of 1.30+-0.40x 10^-11 erg cm^-2 s^-1 in the energy range 20-80 keV. A recent joint XMM-Newton/Suzaku analysis reports an upper limit of ~6x10^-12 erg cm^-2 s^-1 in the energy range 20-80 keV for the nonthermal flux with an average gas temperature of 8.45+-0.06 keV, and an excess of nonthermal radiation at a confidence level above 4sigma, without including systematic effects, for an average XMM-Newton temperature of 8.2 keV in the Suzaku/HXD-PIN FOV, in agreement with our earlier PDS analysis. Here we present a further evidence of the compatibility between the Suzaku and BeppoSAX spectra, obtained by our Supermodel analysis of the PDS data, when the smaller size of the HXD-PIN FOV and the two different average temperatures derived by XMM-Newton and by the joint XMM-Newton/Suzaku analysis are taken into account. The consistency of the PDS and HXD-PIN spectra reaffirms the presence of a nonthermal component in the hard X-ray spectrum of the Coma cluster. The Supermodel analysis of the PDS data reports an excess at c.l. above 4sigma also for the higher average temperature of 8.45 keV thanks to the PDS FOV considerably greater than the HXD-PIN FOV.Comment: 18 pages, 7 figures, accepted for publication in Ap

The giant radio halo in Abell 2163

New radio data is presented for the rich cluster Abell 2163. The cluster radio emission is characterized by the presence of a radio halo, which is one of the most powerful and extended halos known so far. In the NE peripheral cluster region, we also detect diffuse elongated emission, which we classify as a cluster relic. The cluster A2163 is very hot and luminous in X-ray. Its central region is probably in a highly non relaxed state, suggesting that this cluster is likely to be a recent merger. The existence of a radio halo in this cluster confirms that halos are associated with hot massive clusters, and confirms the connection between radio halos and cluster merger processes. The comparison between the radio emission of the halo and the cluster X-ray emission shows a close structural similarity. A power law correlation is found between the radio and X-ray brightness, with index = 0.64. We also report the upper limit to the hard X-ray emission, obtained from a BeppoSAX observation. We discuss the implications of our results.Comment: 7 pages, 8 figures (5 in ps and 3 in gif), Accepted for publication in Astron. Astrop

A new combined protocol to treat the dentin hypersensitivity associated with non-carious cervical lesions: A randomized controlled trial

The goal of this research is to assess the desensitizing effect of a diode laser on noncarious cervical lesions (NCCLs) responsible for dentin hypersensitivity (DH) in two separate output forces implemented both independently and in sequential combination modalities. A randomized controlled trial for this study was applied. Sixty-nine NCCLs responsible for DH pain with severity between 6 and 9 on the VAS scale were considered. Three study groups were developed using just one lesion from three different quadrants of the oral cavity of each patient. All treatment procedures were conducted using a laser diode (810 nm, 5 W) with varying power outputs used separately or in combination. The pain by DH was evaluated at baseline, at treatment completion, and at 15 days and 3 months after each laser procedure. Data analysis was performed using a Wilcoxon test for paired samples, a one-way ANOVA test, and an unpaired t-test. The significant reduction of the mean VAS score was estimated in each study group immediately and at 15 days and 3 months after the end of treatment and compared with the baseline mean VAS score (p-value < 0.0001). The best result concerning the improvement of DH symptomatology was assessed when a combined protocol of two different output powers of the diode laser was used. The authors conclude that the diode laser (810 nm) therapy procedure combining two separate output forces (low and high power) can improve the painful symptoms of DH from NCCLs

Enamel Erosion Reduction through Coupled Sodium Fluoride and Laser Treatments before Exposition in an Acid Environment: An In Vitro Randomized Control SEM Morphometric Analysis

(1) Background: Erosive lesions of dental enamel are steadily increasing owing to both the availability of exogenous acid and the production of endogenous acid. The aim of this study was to investigate the erosion-inhibiting potential of a diode laser irradiation and topical application of fluoride used alone or in combination on the enamel surface of extracted teeth before exposure to an acidic solution. (2) Methods: The four axial enamel surfaces of 40 healthy molars were used for four study groups: (A) no treatment; (B) application of fluoride gel for 120 s; (O) a diode laser application for 120 s; and (X) a combined laser/fluoride for 120 s. Each enamel surface was examined by SEM (scanning electron microscopy). (3) Results: At 700× magnification, it was possible to detect the enamel prisms of the test area of groups A, B, and O, while no structures such as enamel prisms were highlighted for group X because they were covered by an amorphous layer. The mean number of prisms ×1000 µm2 was 7.2 units with an SD of 0.72 for group A, 8 units with an SD of 0.96 for group B, and 4.8 units with a SD of 0.4 for group O. Student’s t-test showed no significant difference between group A and B with a p = 0.054. Group O showed a significant reduction of prims ×1000 µm2 compared with group A (p = 0.0027) and group B (p = 0.0009). Student’s t-test showed no significant difference between groups A and B with a p = 0.054. Group O showed a significant reduction of prims density with respect to group A (p = 0.0027) and group B (p = 0.0009). (4) Conclusions: This amorphous layer might be correlated with the effect of laser on enamel, which reduces both water and carbonate ion; increases the crystallinity of hydroxyapatite, and improves the mechanical properties of enamel; which is responsible for greater protection expressed by the enamel of group X against acid attacks

Entropy Flattening, Gas Clumping and Turbulence in Galaxy Clusters

Several physical processes and formation events are expected in cluster outskirts, a vast region up to now essentially not covered by observations. The recent \textsl{Suzaku} (X-ray) and \textsl{Planck} (Sunayev-Zeldovich effect) observations out to the virial radius have highlighted in these peripheral regions a rather sharp decline of the intracluster gas temperature, an entropy flattening in contrast with the theoretically expected power law increase, the break of the hydrostatic equilibrium even in some relaxed clusters, a derived gas mass fraction above the cosmic value measured from several CMB experiments, and a total X-ray mass lower than the weak lensing mass determinations. Here we present the analysis of four clusters (A1795, A2029, A2204 and A133) with the SuperModel that includes a nonthermal pressure component due to turbulence to sustain the hydrostatic equilibrium also in the cluster outskirts. In such way we obtain a correct determination of the total X-ray mass and of the gas mass fraction; this in turn allows to determine the level of the gas clumping that can affect the shape of the entropy profiles reported by the \textsl{Suzaku} observations. Our conclusion is that the role of the gas clumping is very marginal and that the observed entropy flattening is due to the rapid decrement of the temperature in the cluster outskirts caused by non gravitational effects. Moreover, we show that the X-ray/SZ joint analysis from \textsl{ROSAT} and \textsl{Planck} data, as performed in some recent investigations, is inadequate to discriminate between a power law increase and a flattening of the entropy

SuperModel Analysis of A1246 and J255: On the Evolution of Galaxy Clusters from High to Low Entropy States

We present an analysis of high-quality X-ray data out to the virial radius for the two galaxy clusters A1246 and GMBCG J255.34805+64.23661 (J255) by means of our entropy-based SuperModel. For A1246 we find that the spherically averaged entropy profile of the intracluster medium (ICM) progressively flattens outward, and that a nonthermal pressure component amounting to 4820% of the total is required to support hydrostatic equilibrium in the outskirts; there we also estimate a modest value C 48 1.6 of the ICM clumping factor. These findings agree with previous analyses on other cool-core, relaxed clusters, and lend further support to the picture by Lapi et al. that relates the entropy flattening, the development of the nonthermal pressure component, and the azimuthal variation of ICM properties to weakening boundary shocks. In this scenario clusters are born in a high-entropy state throughout, and are expected to develop on similar timescales a low-entropy state both at the center due to cooling, and in the outskirts due to weakening shocks. However, the analysis of J255 testifies how such a typical evolutionary course can be interrupted or even reversed by merging especially at intermediate redshift, as predicted by Cavaliere et al. In fact, a merger has rejuvenated the ICM of this cluster at z 48 0.45 by reestablishing a high-entropy state in the outskirts, while leaving intact or erasing only partially the low-entropy, cool core at the center

A Grand Design for Galaxy Clusters: Connections and Predictions

We take up from a library of 12 galaxy clusters featuring extended X-ray observations of their Intra Cluster Plasma (ICP), analyzed with our entropy-based Supermodel. Its few intrinsic parameters - basically, the central level and the outer slope of the entropy profile - enable us to uniformly derive not only robust snapshots of the ICP thermal state, but also the 'concentration' parameter marking the age of the host dark matter halo. We test these profiles for consistency with numerical simulations and observations. We find the central and the outer entropy to correlate, so that these clusters split into two main classes defined on the basis of low (LE) or high (HE) entropy conditions prevailing throughout the ICP. We also find inverse correlations between the central/outer entropy and the halo concentration. We interpret these in terms of mapping the ICP progress on timescales around 5 Gyr toward higher concentrations, under the drive of the dark matter halo development. The progress proceeds from HEs to LEs, toward states of deeper entropy erosion by radiative cooling in the inner regions, and of decreasing outer entropy production as the accretion peters out. We propose these radial and time features to constitute a cluster Grand Design, that we use here to derive a number of predictions. For HE clusters we predict sustained outer temperature profiles. For LEs we expect the outer entropy ramp to bend over, hence the temperature decline to steepen at low z; this feature goes together with an increasing turbulent support, a condition that can be directly probed with the SZ effect.Comment: 23 pages, 8 figures, 1 table. Typos corrected. Accepted by Ap