15,490 research outputs found

    Axisymmetric stability criterion for two gravitationally coupled singular isothermal discs

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    Using the two-fluid formalism with the polytropic approximation, we examine the axisymmetric stability criterion for a composite system of gravitationally coupled stellar and gaseous singular isothermal discs (SIDs).Comment: 12 pages, 11 figures, accepted by MNRA

    An Imaging and Spectral Study of Ten X-Ray Filaments around the Galactic Center

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    We report the detection of 10 new X-ray filaments using the data from the {\sl Chandra} X-ray satellite for the inner 66^{\prime} (15\sim 15 parsec) around the Galactic center (GC). All these X-ray filaments are characterized by non-thermal energy spectra, and most of them have point-like features at their heads that point inward. Fitted with the simple absorbed power-law model, the measured X-ray flux from an individual filament in the 2-10 keV band is 2.8×1014\sim 2.8\times10^{-14} to 101310^{-13} ergs cm2^{-2} s1^{-1} and the absorption-corrected X-ray luminosity is 10321033\sim 10^{32}-10^{33} ergs s1^{-1} at a presumed distance of 8 kpc to the GC. We speculate the origin(s) of these filaments by morphologies and by comparing their X-ray images with the corresponding radio and infrared images. On the basis of combined information available, we suspect that these X-ray filaments might be pulsar wind nebulae (PWNe) associated with pulsars of age 1033×10510^3 \sim 3\times 10^5 yr. The fact that most of the filament tails point outward may further suggest a high velocity wind blowing away form the GC.Comment: 29 pages with 7 figures and 3 pages included. Accepted to Ap

    Periodic and Localized Solutions of the Long Wave-Short Wave Resonance Interaction Equation

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    In this paper, we investigate the (2+1) dimensional long wave-short wave resonance interaction (LSRI) equation and show that it possess the Painlev\'e property. We then solve the LSRI equation using Painlev\'e truncation approach through which we are able to construct solution in terms of three arbitrary functions. Utilizing the arbitrary functions present in the solution, we have generated a wide class of elliptic function periodic wave solutions and exponentially localized solutions such as dromions, multidromions, instantons, multi-instantons and bounded solitary wave solutions.Comment: 13 pages, 6 figure
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