The Variation of Gas Mass Distribution in Galaxy Clusters: Effects of Preheating and Shocks

We investigate the origin of the variation of the gas mass fraction in the core of galaxy clusters, which was indicated by our work on the X-ray fundamental plane. The adopted model supposes that the gas distribution characterized by the slope parameter is related to the preheated temperature. Comparison with observations of relatively hot (~> 3 keV) and low redshift clusters suggests that the preheated temperature is about 0.5-2 keV, which is higher than expected from the conventional galactic wind model and possibly suggests the need for additional heating such as quasars or gravitational heating on the largest scales at high redshift. The dispersion of the preheated temperature may be attributed to the gravitational heating in subclusters. We calculate the central gas fraction of a cluster from the gas distribution, assuming that the global gas mass fraction is constant within a virial radius at the time of the cluster collapse. We find that the central gas density thus calculated is in good agreement with the observed one, which suggests that the variation of gas mass fraction in cluster cores appears to be explained by breaking the self-similarity in clusters due to preheated gas. We also find that this model does not change major conclusions on the fundamental plane and its cosmological implications obtained in previous papers, which strongly suggests that not only for the dark halo but also for the intracluster gas the core structure preserves information about the cluster formation.Comment: 17 pages, to be published in Ap

Quantum Optics with Surface Plasmons

We describe a technique that enables strong, coherent coupling between individual optical emitters and guided plasmon excitations in conducting nano-structures at optical frequencies. We show that under realistic conditions, optical emission can be almost entirely directed into the plasmon modes. As an example, we describe an application of this technique involving efficient generation of single photons on demand, in which the plasmon is efficiently out-coupled to a dielectric waveguide.Comment: 11 pages, 3 figure

Improved microscopic-macroscopic approach incorporating the effects of continuum states

The Woods-Saxon-Strutinsky method (the microscopic-macroscopic method) combined with Kruppa's prescription for positive energy levels, which is necessary to treat neutron rich nuclei, is studied to clarify the reason for its success and to propose improvements for its shortcomings. The reason why the plateau condition is met for the Nilsson model but not for the Woods-Saxon model is understood in a new interpretation of the Strutinsky smoothing procedure as a low-pass filter. Essential features of Kruppa's level density is extracted in terms of the Thomas-Fermi approximation modified to describe spectra obtained from diagonalization in truncated oscillator bases. A method is proposed which weakens the dependence on the smoothing width by applying the Strutinsky smoothing only to the deviations from a reference level density. The BCS equations are modified for the Kruppa's spectrum, which is necessary to treat the pairing correlation properly in the presence of continuum. The potential depth is adjusted for the consistency between the microscopic and macroscopic Fermi energies. It is shown, with these improvements, that the microscopic-macroscopic method is now capable to reliably calculate binding energies of nuclei far from stability.Comment: 66 pages, 29 figures, 1 tabl

High-hole mobility Si1-xGex (0.1 ≤ x ≤ 1) on an insulator formed by advanced solid-phase crystallization

The grain size and hole mobility of polycrystalline Si1-xGex thin films formed on glass by solid-phase crystallization were significantly improved after preparing the amorphous precursors by heating the substrate. By just controlling the deposition temperature of the precursors (50–350 °C) for each SiGe composition, the grain size reached over 2 μm across the whole composition range. Reflecting the enlargement of the grain size, the hole mobility values were improved by approximately one order of magnitude. These values are comparable to those of single-crystal SiGe formed by Ge condensation and are the highest among SiGe on insulators synthesized at low temperature (<900 °C). The SiGe on insulator technology obtained in this study will greatly contribute to the development of SiGe-based electronic and optical devices

Graph-Controlled Insertion-Deletion Systems

In this article, we consider the operations of insertion and deletion working in a graph-controlled manner. We show that like in the case of context-free productions, the computational power is strictly increased when using a control graph: computational completeness can be obtained by systems with insertion or deletion rules involving at most two symbols in a contextual or in a context-free manner and with the control graph having only four nodes.Comment: In Proceedings DCFS 2010, arXiv:1008.127

Coherent Curvature Radiation and Proton Counterflow in the Pulsar Magnetosphere

In the proton counterflow model of a pulsar magnetosphere that we have recently proposed, non-relativistic protons are supplied from the magnetosphere to flow toward the pulsar surface and screen an electric field above the polar cap region. In this Letter, we show that the proton counterflow is also suitable for the bunching of pair plasma. The two-stream instability is easily excited and can produce bunches of pairs with a relevant length scale to emit coherent curvature radiation.Comment: 11pages, 1 figur

Density-matrix formalism with three-body ground-state correlations

A density-matrix formalism which includes the effects of three-body ground- state correlations is applied to the standard Lipkin model. The reason to consider the complicated three-body correlations is that the truncation scheme of reduced density matrices up to the two-body level does not give satisfactory results to the standard Lipkin model. It is shown that inclusion of the three-body correlations drastically improves the properties of the ground states and excited states. It is pointed out that lack of mean-field effects in the standard Lipkin model enhances the relative importance of the three-body ground-state correlations. Formal aspects of the density-matrix formalism such as a relation to the variational principle and the stability condition of the ground state are also discussed. It is pointed out that the three-body ground-state correlations are necessary to satisfy the stability condition

On the Origin of the Highest Energy Cosmic Rays

We present the results of a new estimation of the photodisintegration and propagation of ultrahigh energy cosmic ray (UHCR) nuclei in intergalactic space. The critical interactions for photodisintegration and energy loss of UHCR nuclei occur with photons of the infrared background radiation (IBR). We have reexamined this problem making use of a new determination of the IBR based on empirical data, primarily from IRAS galaxies, and also collateral information from TeV gamma-ray observations of two nearby BL Lac objects. Our results indicate that a 200 EeV Fe nucleus can propagate apx. 100 Mpc through the IBR. We argue that it is possible that the highest energy cosmic rays observed may be heavy nuclei.Comment: 2 pages revtex with one figure, submitted to Physical Review Letter

Quantum Statistics of Surface Plasmon Polaritons in Metallic Stripe Waveguides

Single surface plasmon polaritons are excited using photons generated via spontaneous parametric down-conversion. The mean excitation rates, intensity correlations and Fock state populations are studied. The observed dependence of the second order coherence in our experiment is consistent with a linear uncorrelated Markovian environment in the quantum regime. Our results provide important information about the effect of loss for assessing the potential of plasmonic waveguides for future nanophotonic circuitry in the quantum regime.Comment: 21 pages, 6 figures, published in Nano Letters, publication date (web): March 27 (2012

Robust plasmon waveguides in strongly-interacting nanowire arrays

Arrays of parallel metallic nanowires are shown to provide a tunable, robust, and versatile platform for plasmon interconnects, including high-curvature turns with minimum signal loss. The proposed guiding mechanism relies on gap plasmons existing in the region between adjacent nanowires of dimers and multi-wire arrays. We focus on square and circular silver nanowires in silica, for which excellent agreement between both boundary element method and multiple multipolar expansion calculations is obtained. Our work provides the tools for designing plasmon-based interconnects and achieving high degree of integration with minimum cross talk between adjacent plasmon guides.Comment: 4 pages, 5 figure