13,099 research outputs found

    Reflexivity of the automorphism and isometry groups of the suspension of B(H)B(H)

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    The aim of this paper is to show that the automorphism and isometry groups of the suspension of B(H)B(H), HH being a separable infinite dimensional Hilbert space, are algebraically reflexive. This means that every local automorphism, respectively local surjective isometry of C0(R)⊗B(H)C_0(\mathbb R)\otimes B(H) is an automorphism, respectively a surjective isometry

    Linear maps on the space of all bounded observables preserving maximal deviation

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    In this paper we determine all the bijective linear maps on the space of bounded observables which preserve a fixed moment or the variance. Nonlinear versions of the corresponding results are also presented.Comment: 27 pages. To appear in J. Funct. Ana

    Metal line blanketing and opacity in the ultraviolet of alpha 2 Canum Venaticorum

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    Ultraviolet photometry by OAO-2 was made of alpha 2 CVn covering the entire 5.5d period of this magnetic Ap variable. The light curves ranging from 1330 A to 3320 A indicate the dominant role of rare-earth line-blanketing in redistributing flux. In a broad depression of the continuum covering 2300-2600 A, scanner observations possibly identify strong lines of Eu III as major contributors to this feature. At maximum intensity of the rare-earth lines, the ultraviolet continuum shortward of 2900 A is greatly diminished while the longer wavelength regions into the visual become brighter. In addition, there is evidence that the hydrogen line opacity is variable and the photoionization edge of Si I at 1680 A is identified

    Shocks and Tides Quantified in the "Sausage" Cluster, CIZA J2242.8+5301, using N-body/hydro-dynamical Simulations

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    The colliding cluster, CIZA J2242.8+5301, displays a spectacular, almost 2 Mpc long shock front with a radio based Mach number M ~ 5, that is puzzlingly large compared with the X-ray estimate of M ~ 2.5. The extent to which the X-ray temperature jump is diluted by cooler unshocked gas projected through the cluster currently lacks quantification. Thus, here we apply our self-consistent N-body/hydro-dynamical code (based on FLASH) to model this binary cluster encounter. We can account for the location of the shock front and also the elongated X-ray emission by tidal stretching of the gas and dark matter between the two cluster centers. The required total mass is 8.9×10148.9 \times 10^{14} Msun with a 1.3:1 mass ratio favoring the southern cluster component. The relative velocity we derive is ≃2500\simeq 2500 km/s initially between the two main cluster components, with an impact parameter of 120 kpc. This solution implies that the shock temperature jump derived from the low angular resolution X-ray satellite SUZAKU is underestimated by a factor of two, due to cool gas in projection, bringing the observed X-ray and radio estimates into agreement. We propose that the complex southern relics in CIZA J2242.8+5301, have been broken up as the southerly moving "back" shocked gas impacts the gas still falling in along the collision axis. Finally, we use our model to generate Compton-y maps to estimate the reduction in radio flux caused by the thermal Sunyaev-Zel'dovich (SZ) effect. At 30 GHz, this amounts to ΔSn=−0.072\Delta S_n = -0.072 mJy/arcmin2^2 and ΔSs=−0.075\Delta S_s = -0.075 mJy/arcmin2^2 at the locations of the northern and southern shock fronts respectively. Our model estimate agrees with previous empirical estimates that have inferred the measured radio spectra can be significantly affected by the SZ effect, with implications for charged particle acceleration models of the radio relics.Comment: 8 pages, 7 figures and 1 table, submitted to the Astrophysical Journal for publication on March

    Multi-Phenomena Modeling of the New Bullet Cluster, ZwCl008.8+52, using N-body/hydrodynamical Simulations

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    We use hydrodynamical/N-body simulations to interpret the newly discovered Bullet-cluster-like merging cluster, ZwCl 0008.8+5215 (ZwCl 0008 hereafter), where a dramatic collision is apparent from multi-wavelength observations. We have been able to find a self-consistent solution for the radio, X-ray, and lensing phenomena by projecting an off-axis, binary cluster encounter viewed just after first core passage. A pair radio relics traces well the leading and trailing shock fronts that our simulation predict, providing constraints on the collision parameters. We can also account for the observed distinctive comet-like X-ray morphology and the positions of the X-ray peaks relative to the two lensing mass centroids and the two shock front locations. Relative to the Bullet cluster, the total mass is about 70% lower, (1.2±0.1)×10151.2\pm0.1) \times 10^{15} Msun, with a correspondingly lower infall velocity, 1800±3001800\pm300 km/s, and an impact parameter of 400±100400\pm100 kpc. As a result, the gas component of the infalling cluster is not trailing significantly behind the associated dark matter as in the case of the Bullet cluster. The degree of agreement we find between all the observables provides strong evidence that dark matter is effectively collisionless on large scales calling into question other claims and theories that advocate modified gravity.Comment: 9 pages, 3 figures, and 1 table, submitted to the Astrophysical Journal for publicationon on December 18. Coments are welcom

    A Hydrodynamical Solution for the "Twin-Tailed" Colliding Galaxy Cluster "El Gordo"

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    The distinctive cometary X-ray morphology of the recently discovered massive galaxy cluster "El Gordo" (ACT-CT J0102-4915; z=0.87) indicates that an unusually high-speed collision is ongoing between two massive galaxy clusters. A bright X-ray "bullet" leads a "twin-tailed" wake, with the SZ centroid at the end of the Northern tail. We show how the physical properties of this system can be determined using our FLASH-based, N-body/hydrodynamic model, constrained by detailed X-ray, Sunyaev-Zel'dovich (SZ), and Hubble lensing and dynamical data. The X-ray morphology and the location of the two Dark Matter components and the SZ peak are accurately described by a simple binary collision viewed about 480 million years after the first core passage. We derive an impact parameter of ~300 kpc, and a relative initial infall velocity of ~2250 km/sec when separated by the sum of the two virial radii assuming an initial total mass of 2.15x10^(15) Msun and a mass ratio of 1.9. Our model demonstrates that tidally stretched gas accounts for the Northern X-ray tail along the collision axis between the mass peaks, and that the Southern tail lies off axis, comprising compressed and shock heated gas generated as the massive component plunges through the main cluster. The challenge for LCDM will be to find out if this physically extreme event can be plausibly accommodated when combined with the similarly massive, high infall velocity case of the "Bullet cluster" and other such cases being uncovered in the new SZ based surveys.Comment: 9 pages, 5 Figures and 1 Table, accepted for publication in the Astrophysical Journa

    Flavor ordering of elliptic flows at high transverse momentum

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    Based on the quark coalescence model for the parton-to-hadron phase transition in ultra-relativistic heavy ion collisions, we relate the elliptic flow (v2v_2) of high \pt hadrons to that of high \pt quarks. For high \pt hadrons produced from an isospin symmetric and quark-antiquark symmetric partonic matter, magnitudes of their elliptic flows follow a flavor ordering as (v2,π=v2,N)>(v2,Λ=v2,Σ)>v2,K>v2,Ξ>(v2,ϕ=v2,Ω)(v_{2,\pi}=v_{2,N}) > (v_{2,\Lambda}=v_{2,\Sigma}) > v_{2,K} > v_{2,\Xi} > (v_{2,\phi}=v_{2,\Omega}) if strange quarks have a smaller elliptic flow than light quarks. The elliptic flows of high \pt hadrons further follow a simple quark counting rule if strange quarks and light quarks have same high \pt spectrum and coalescence probability.Comment: 4 pages, 1 figure, revte

    Geophysical study of the structure and processes of the continental convergence zones: Alpine-Himalayan belt

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    Studies of the structure of the continental collision zones using seismic and body waves, theoretical modelling of the thermal regime of the convergence processes, and studies of earthquake mechanisms and deformation aspects of the model are covered
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