December 2005 arXiv papers — page 35

F. Pellegrini

This paper concerns a super Poisson-Lie structure on the real Lie supergroup $SU(m \ve n)$. In fact, it turns out that the realification of the complex Lie supergroup $SL(m \ve n, \C)$ is a double of $SU(m \ve n)$ i.e. it is endowed with a structure of super Poisson-Lie which brings down on the supergroup $SU(m \ve n)$. We show that the dual Poisson-Lie supe

Maria Joita

The crossed products of locally C*-algebras are defined and a Takai duality theorem for inverse limit actions of a locally compact group on a locally C*-algebra is proved.

Joseph Coffey

Let M and N be closed n-dimensional manifolds, and equip N with a volume form σ. Let μbe an exact n-form on M. Arnold then asked the question: When can one find a map f:;N such that f*σ=μ. In 1973 Eliashberg and Gromov showed that this problem is, in a deep sense, trivial: It satisfies an h-principle, and whenever one can find a bundle map f_bdl:T M to T N w

Thorsten Holm, Radha Kessar, Markus Linckelmann

Except for blocks with a cyclic or Klein four defect group, it is not known in general whether the Morita equivalence class of a block algebra over a field of prime characteristic determines that of the corresponding block algebra over a p-adic ring. We prove this to be the case when the defect group is quaternion of order 8 and the block algebra over an alg

V. Laptev

We consider non-homogeneous media with properties which can be characterized by rapidly oscillated coefficients. For such coefficients we define a notion of two-scale extension, present several ways to construct two-scale extensions, discuss their properties and relation to homogenization

Enrico De Micheli, Giovanni Alberto Viano

In this article we prove that if the coefficients of a Fourier-Legendre expansion satisfy a suitable Hausdorff-type condition, then the series converges to a function which admits a holomorphic extension to a cut-plane. Furthermore, we prove that a Laplace-type (Laplace composed with Radon) transform of the function describing the jump across the cut is the

Bhalchandra D. Thatte

A modified $k$-deck of a graph $G$ is obtained by removing $k$ edges of $G$ in all possible ways, and adding $k$ (not necessarily new) edges in all possible ways. Krasikov and Roditty asked if it was possible to construct the usual $k$-edge deck of a graph from its modified $k$-deck. Earlier I solved this problem for the case when $k=1$. In this paper, the p

Hiroshi Goda, Chuichiro Hayashi, Hyun-Jong Song

We determine the Dehn surgeries on 2-bridge links, which yield reducible 3-manifolds. Further, we show the conditions that we obtain a torus or cable knot from one component of a 2-bridge link by a surgery on another component.

David Ginzburg, Joseph Hundley

In this paper we construct a Rankin-Selberg integral which represents the Spin_10 x St L-function attached to the group GSO_10 x PGL_2. We use this integral representation to give some equivalent conditions for a generic cuspidal representation on GSO_10 to be a functorial lift from the group G_2 x PGL_2.

Laurent Hauswirth, Ricardo Sa Earp, Eric Toubiana

We consider minimal immersions in MxR. We study existence and uniqueness of associate and conjugate isometric immersions to a given minimal surface. We use the theory of univalent harmonic map between surfaces. Then we study the geometry of associate minimal vertical graphs. We prove that an associate surface of a vertical graph on a convex domain is a graph

Louis H. Kauffman, R. Bruce Richter

This paper gives a polynomial invariant for flat virtual links. In the case of one component, the polynomial specializes to Turaev's virtual string polynomial. We show that Turaev's polynomial has the property that it is non-zero precisely when there is no filamentation of the knot, as described by Hrencecin and Kauffman. Schellhorn has provided a ve

F. Klebaner, R. Liptser

We give an explicit formula for the most likely path to extinction for the Galton-Watson processes with large initial population. We establish this result with the help of the large deviation principle (LDP) which also recovers the asymptotics of extinction probability. Due to the nonnegativity of the Galton-Watson processes, the proof of LDP verification at

Dmitry N. Kozlov

Combinatorics, in particular graph theory, has a rich history of being a domain of successful applications of tools from other areas of mathematics, including topological methods. Here, we survey the study of the Hom-complexes, and the ways these can be used to obtain lower bounds for the chromatic numbers of graphs, presented in a recent series of papers \c

Anton Deitmar

A general Lefschetz formula for the geodesic action on locally symmetric spaces is proven.

Raphael Ponge

In this paper we define an intrinsic notion of principal for the Hypoelliptic calculus on Heisenberg manifolds. More precisely, the principal symbol of a \psivdo appears as a homogeneous section over the linear dual of the tangent Lie algebra bundle of the manifold. This definition is an important step towards using global $K$-theoretic tools in the Heisenbe

Raphael Ponge

This paper is part of a series papers devoted to geometric and spectral theoretic applications of the hypoelliptic calculus on Heisenberg manifolds. More specifically, in this paper we make use of the Heisenberg calculus of Beals-Greiner and Taylor to analyze the spectral theory of hypoelliptic operators on Heisenberg manifolds. The main results of this pape

R. Balasubramanian, Gyan Prakash

Let A be a subset of a finite abelian group G. We say that A is sum-free if there is no solution of the equation x + y = z, with x, y, z belonging to the set A. In this paper we shall characterise the largest possible sum-free subsets of G in case the order of G is only divisible by primes which are congruent to 1 modulo 3. The result is based on a recent re

Mark Braverman, Michael Yampolsky

We show that under the definition of computability which is natural from the point of view of applications, there exist non-computable quadratic Julia sets.

T. E. Clark, S. T. Love, Muneto Nitta, T. ter Veldhuis

Coset methods are used to construct the action describing the dynamics associated with the spontaneous breaking of the local supersymmetries. The resulting action is an invariant form of the Einstein-Hilbert action, which in addition to the gravitational vierbein, also includes a massive gravitino field. Invariant interactions with matter and gauge fields ar

Hassan Firouzjahi, S. -H. Henry Tye

We study the spectrum of the gravitational modes in Minkowski spacetime due to a 6-dimensional warped deformed conifold, i.e., a warped throat, in superstring theory. After identifying the zero mode as the usual 4D graviton, we present the KK spectrum as well as other excitation modes. Gluing the throat to the bulk (a realistic scenario), we see that the gra

Andrei Parnachev, David A. Sahakyan

An interesting case of string/black hole transition occurs in two-dimensional non-critical string theory dressed with a compact CFT. In these models the high energy densities of states of perturbative strings and black holes have the same leading behavior when the Hawking temperature of the black hole is equal to the Hagedorn temperature of perturbative stri

Luis Gonzalez-Diaz, Victor M. Villalba

We show that the energy spectrum of the one-dimensional Dirac equation in the presence of a spatial confining point interaction exhibits a resonant behavior when one includes a weak electric field. After solving the Dirac equation in terms of parabolic cylinder functions and showing explicitly how the resonant behavior depends on the sign and strength of the

V. Elias, S. Homayouni, D. J. Jeffrey

We consider dominant 3-, 4-, and 5-loop contributions to $λ$, the quartic scalar coupling-constant's $β$-function in the Standard Model. We find that these terms accelerate the evolution of $λ$ to nonperturbative values, thereby lowering the unification bound for which scalar-couplings are still perturbative. We also find that these higher order contribu

Richard J. Szabo

A survey of the interrelationships between matrix models and field theories on the noncommutative torus is presented. The discretization of noncommutative gauge theory by twisted reduced models is described along with a rigorous definition of the large N continuum limit. The regularization of arbitrary noncommutative field theories by means of matrix quantum

V. Bozza

Bouncing cosmologies, suggested by String/M-theory, may provide an alternative to standard inflation to account for the origin of inhomogeneities in our universe. The fundamental question regards the correct way to evolve the scalar perturbations through the bounce. In this work, we determine the evolution of perturbations and the final spectrum for an arbit

Duoje Jia

It has long argued that confinement in non-Abelian gauge theories, such as QCD, can be account for by analogy with typed II superconductivity. In this paper, we show that it is possible to arrive at an effective dual Abelian-Higgs model, the dual and relativistic version of Ginzburg-Landau model for superconductor, from SU(2) Yang-Mills theory based on the F

S. Benvenuti, M. Mahato, L. A. Pando Zayas, Y. Tachikawa

We present an explicit supersymmetric deformation of supergravity backgrounds describing D3-branes on Calabi-Yau cones. From the geometrical point of view, it corresponds to blowing up a 4-cycle in the Calabi-Yau and can be done universally. In the field theory, we identify this deformation with motion on non-mesonic directions in the full moduli space of va

Shu-Pian Tang

This paper was removed by arXiv admin due to 94% plagiarism from uncited reference hep-th/0507153.

L. Bergamin

2D dilaton (super-)gravity contains a special class of solutions with constant dilaton, a kink-like solution connecting two of them was recently found in a specific model that corresponds to the KK reduced 3D Chern-Simons term. Here we develop the systematics of such solutions in generalized 2D dilaton gravity and supergravity. The existence and characterist

N. Evans, F. Sannino

We consider a minimal technicolour theory with two techniflavours in the adjoint representation of an SU(2) technicolour gauge group which has been argued to feature walking dynamics. We show how to naturally embed this theory in an extended technicolour model capable of generating the top quark mass. We investigate the precision constraints and conclude tha

Francois Gelis, Yacine Mehtar-Tani

We show that, in the light-cone gauge, it is possible to derive in a very simple way the solution of the classical Yang-Mills equations for the collision between a nucleus and a proton. One important step of the calculation is the derivation of a formula that describes the propagation of a gluon in the background color field of the nucleus. This allows us to

Pei-Hong Gu, Xiao-Jun Bi, Bo Feng, Bing-Lin Young

In this paper, we discuss a possibility of studying properties of dark energy in long baseline neutrino oscillation experiments. We consider two types of models of neutrino dark energy. For one type of models the scalar field is taken to be quintessence-like and for the other phantom-like. In these models the scalar fields couple to the neutrinos to give ris

Ekaterina Christova, Elliot Leader

We show that non-singlets in semi-inclusive DIS with pi^\pm determine without assumptions Delta u_V, Delta d_V and D_u^{π+ - pi-}. Non-singlets in SIDIS and inclusive e+e- -annihilation with K^\pm determine (s-bar s) and (Delta s-Delta bar s), but an assumption is necessary -- we choose as most natural D_d^{K+ - K-}=0. Measurements with charged K^\pm and neu

Ezequiel Alvarez, Jose Bernabeu, Miguel Nebot

In this work we discuss how the loss of particle-antiparticle identity due to CPT violation affects the observables in the decay of two neutral EPR-correlated $B$-mesons. We study this possible new effect in the context of equal-sign flavour specific decays and we find a considerable modification in the $Δt$-dependence of the equal-sign dilepton charge asymm

A. M. Teixeira

We analyse the phenomenological viability of heterotic $Z_3$ orbifold models with two Wilson lines, which naturally predict three families of matter and Higgs fields. We study the orbifold parameter space, and discuss the compatibility of the predicted Yukawa couplings with current experimental data, thus evaluating the viability of the orbifold configuratio

The DELPHI Collaboration, J. Abdallah

This paper presents DELPHI measurements and interpretations of cross-sections, forward-backward asymmetries, and angular distributions, for the e+e- -> ffbar process for centre-of-mass energies above the Z resonance, from sqrt(s) ~ 130 - 207 GeV at the LEP collider. The measurements are consistent with the predictions of the Standard Model and are used to st

K. E. Shestermanov, A. N. Vasiliev, J. Butler, A. A. Derevschikov

A precise measurement of the angle $α$ in the CKM triangle is very important for a complete test of Standard Model. A theoretically clean method to extract $α$ is provided by B$^0 \to ρπ$ decays. Monte Carlo simulations to obtain the BTeV reconstruction efficiency and to estimate the signal to background ratio for these decays were performed. Finally the tim

Zhenyu Ye

Measurements of deeply virtual Compton scattering (DVCS) made at HERMES using 27.6 GeV $e^\pm$ beams and various internal polarized or unpolarized gaseous targets are discussed. Results are reported on the transverse target-spin asymmetry (TTSA) associated with DVCS, extracted from data accumulated in 2002-2004 with the $e^+$ beam on a transversely polarized

Piotr T. Chrusciel, Daniel Maerten

We show that the borderline cases in the proof of the positive energy theorem for initial data sets, on spin manifolds, in dimensions $n\ge 3$, are only possible for initial data arising from embeddings in Minkowski space-time.

Piotr T. Chrusciel, Harvey S. Reall, Paul Tod

We present a simple proof of the non-existence of degenerate components of the event horizon in static, vacuum, regular, four-dimensional black hole spacetimes. We discuss the generalisation to higher dimensions and the inclusion of a cosmological constant.

Arkady Kheyfets, Warner A. Miller, Ruslan Vaulin

The canonical quantum theory of gravity -- Quantum Geometrodynamics (QG) is applied to the homogeneous Bianchi type IX cosmological model. As a result, the framework for the quantum theory of homogeneous cosmologies is developed. We show that the theory is internally consistent, and prove that it possesses the correct classical limit (the theory of general r

Vincent Corbin, Neil J. Cornish

The detection of the Cosmic Microwave Background Radiation (CMB) was one of the most important cosmological discoveries of the last century. With the development of interferometric gravitational wave detectors, we may be in a position to detect the gravitational equivalent of the CMB in this century. The Cosmic Gravitational Background (CGB) is likely to be

Alexander A. Andrianov, Francesco Cannata, Alexander Y. Kamenshchik

Inspired by the generalization of quantum theory for the case of non-Hermitian Hamiltonians with CPT symmetry, we construct a simple classical cosmological scalar field based model describing a smooth transition from ordinary dark energy to the phantom one.

Narayan Banerjee, Sudipta Das

In this paper, it is shown completely analytically that a spintessence model can very well serve the purpose of providing an early deceleration and the present day acceleration.

Jianyong Shen, Rong-Gen Cai, Bin Wang, Ru-Keng Su

Based on the observations that there exists an analogy between the Reissner-Nordström-anti-de Sitter (RN-AdS) black holes and the van der Waals-Maxwell liquid-gas system, in which a correspondence of variables is $(ϕ, q) \leftrightarrow (V,P)$, we study the Ruppeiner geometry, defined as Hessian matrix of black hole entropy with respect to the internal energ

Sascha Husa, Carsten Schneemann, Tilman Vogel, Anil Zenginoglu

We discuss the hyperboloidal evolution problem in general relativity from a numerical perspective, and present some new results. Families of initial data which are the hyperboloidal analogue of Brill waves are constructed numerically, and a systematic search for apparent horizons is performed. Schwarzschild-Kruskal spacetime is discussed as a first applicati

Petros Elia, B. A. Sethuraman, P. Vijay Kumar

Perfect space-time codes were first introduced by Oggier et. al. to be the space-time codes that have full rate, full diversity-gain, non-vanishing determinant for increasing spectral efficiency, uniform average transmitted energy per antenna and good shaping of the constellation. These defining conditions jointly correspond to optimality with respect to the

Louis Mello

This paper discusses the use of fat-tailed distributions in catastrophe prediction as opposed to the more common use of the Normal Distribution.

Rajesh M. Pampapathi, Boris Mirkin, Mark Levene

We present an approach to email filtering based on the suffix tree data structure. A method for the scoring of emails using the suffix tree is developed and a number of scoring and score normalisation functions are tested. Our results show that the character level representation of emails and classes facilitated by the suffix tree can significantly improve c

Josiah Carlson, David Eppstein

We consider problems in which we are given a rooted tree as input, and must find a subtree with the same root, optimizing some objective function of the nodes in the subtree. When this function is the sum of constant node weights, the problem is trivially solved in linear time. When the objective is the sum of weights that are linear functions of a parameter

Michael A. Bender, David P. Bunde, Erik D. Demaine, Sandor P. Fekete

This paper gives processor-allocation algorithms for minimizing the average number of communication hops between the assigned processors for grid architectures, in the presence of occupied cells. The simpler problem of assigning processors on a free grid has been studied by Karp, McKellar, and Wong who show that the solutions have nontrivial structure; they

C. A. Marlow, R. P. Taylor, M. Fairbanks, H. Linke

Magnetoconductance fluctuations are used to study the effect of an applied bias on an electron billiard. At lower bias, nonlinear effects can be well described by electron heating alone, while at higher bias (V > 2mV, ~5% of the electron Fermi energy) non-equilibrium effects become significant. At high bias, we also observe that the spectral content of the M

A. M. Bobkov

The Josephson current between d-wave superconductors is investigated in the framework of tight-binding lattice model. The junction is modelled by a small number of connecting bonds. It is obtained that the Josephson current through one bond vanishes when at least one of the superconductors has $(110)$ interface-to-crystal orientation. Interference between th

Michael D. Fischbein, Marija Drndic

We report a method for fabricating nanogaps directly with electron beam lithography (EBL). The primary resolution-limit of EBL, electron back-scattering, is reduced dramatically by using a thin-film as a substrate. We show that this resolution enhancement allows one to fabricate metal electrodes with separation from arbitrarily large to under one nanometer.

Jeetain Mittal, Jeffrey R. Errington, Thomas M. Truskett

We study how confining the equilibrium hard-sphere fluid to restrictive one- and two-dimensional channels with smooth interacting walls modifies its structure, dynamics, and entropy using molecular dynamics and transition-matrix Monte Carlo simulations. Although confinement strongly affects local structuring, the relationships between self-diffusivity, exces

C. F. Sanchez Valdes, C. Perez-Penichet, C. Noda, M. Aronte

The determination of inter- and intra-filament transport characteristics in superconducting composites such as BSCCO-Ag tapes is of great importance for material evaluation towards applications. Most attempts to separate the two contributions have relied on indirect methods based on magnetic measurements such as SQUID or magneto-optic imaging techniques. Her

M. Tasinkevych, J. M. Tavares, F. de los Santos

Computer simulations are used to generate two-dimensional diffusion-limited deposits of dipoles. The structure of these deposits is analyzed by measuring some global quantities: the density of the deposit and the lateral correlation function at a given height, the mean height of the upper surface for a given number of deposited particles and the interfacial

Yu. A. Kolesnichenko, S. N. Shevchenko

A stationary Josephson effect is analyzed theoretically for a weak link between borocarbide superconductors. It is shown that different models of the order parameter result in qualitatively different current-phase relations.

Almut Beige

Quantum computing tries to exploit entanglement and interference to process information more efficiently than the best known classical solutions. Experiments demonstrating the feasibility of this approach have already been performed. However, finding a really scalable and robust quantum computing architecture remains a challenge for both, experimentalists an

A. F. Koenderink, M. Kafesaki, C. M. Soukoulis, V. Sandoghdar

We show theoretically that finite two-dimensional (2D) photonic crystals in thin semiconductor membranes strongly modify the spontaneous emission rate of embedded dipole emitters. Three-dimensional Finite-Difference Time-Domain calculations show over 7 times inhibition and 15 times enhancement of the emission rate compared to the vacuum emission rate for jud

Stefan Klumpp, Melanie J. I. Müller, Reinhard Lipowsky

Molecular motors perform active movements along cytoskeletal filaments and drive the traffic of organelles and other cargo particles in cells. In contrast to the macroscopic traffic of cars, however, the traffic of molecular motors is characterized by a finite walking distance (or run length) after which a motor unbinds from the filament along which it moves

K. Tanaka, D. F. Agterberg, J. Kopu, M. Eschrig

Motivated by the recent results on impurity effects in MgB2, we present a theoretical model for a two-band superconductor in which the character of quasiparticle motion is ballistic in one band and diffusive in the other. We apply our model to calculate the electronic structure in the vicinity of an isolated vortex. We assume that superconductivity in the di

John M. Tranquada

Neutron scattering studies have provided important information about the momentum and energy dependence of magnetic excitations in cuprate superconductors. Of particular interest are the recent indications of a universal magnetic excitation spectrum in hole-doped cuprates. That starting point provides motivation for reviewing the antiferromagnetic state of t

Nicolas Emery, Claire Herold, Jean-Francois Mareche, Christine Bellouard

In this letter, we report the discovery of superconductivity in Li3Ca2C6. Several graphite intercalation compounds (GICs) with electron donors, are well known as superconductors. It is probably not astonishing, since it is generally admitted that low dimensionality promotes high superconducting transition temperatures. Superconductivity is lacking in pristin

Aveek Bid, Achyut Bora, A. K. Raychaudhuri

We have measured the low-frequency resistance fluctuations (1 mHz<f<10 Hz) in Ag nanowires of diameter 15 nm<d<200 nm at room temperatures. The power spectral density (PSD) of the fluctuations has a 1/f^α character as seen in metallic films and wires of larger dimension. Additionally, the PSD has a significant low-frequency component and the value of αincrea

M. N. Chernodub, E. -M. Ilgenfritz, A. Schiller

We study the phase structure of a three dimensional Abelian Higgs model with singly- and doubly-charged scalar fields coupled to a compact Abelian gauge field. The model is pretending to describe systems of strongly correlated electrons such as high-Tc superconductivity in overdoped regime and exotic phases supporting excitations with fractionalized quantum

S. N. Shevchenko, Yu. A. Kolesnichenko

The conductance of a ballistic elliptically shaped quantum wire is investigated theoretically. It is shown that the effect of the curvature results in strong oscillating dependence of the conductance on the applied bias.

Jure Demsar, Verner K. Thorsmolle, John L. Sarrao, Antoinette J. Taylor

We have studied the photoexcited carrier relaxation dynamics in the Kondo insulator SmB6 and the heavy fermion metal YbAgCu4 as a function of temperature and excitation level. The dynamic response is found to be both strongly temperature dependent and nonlinear. The data are analyzed with a Rothwarf-Taylor bottleneck model, where the dynamics are governed by

S. B. Santra, B. Sapoval

Ballistic particles interacting with irregular surfaces are representative of many physical problems in the Knudsen diffusion regime. In this paper, the collisions of ballistic particles interacting with an irregular surface modeled by a quadratic Koch curve, are studied numerically. The $q$ moments of the source spatial distribution of collision numbers $μ(

P. Udomsamuthirun, A. Changjan, C. Kumvongsa, S. Yoksan

The purpose of this research is to study the upper critical field (Hc2) of two-band superconductors by two-band Ginzburg - Landau approach. The analytical formula of Hc2 included anisotropy of order parameter and anisotropy of effective-mass are found . The parameters of the upper critical field in ab-plane and c-axis can be found by fitting to the experimen

Rong Yang, Haiqiang Yang, Arthur R. Smith

We have investigated the growth of antiferromagnetic Mn3N2(001) on MgO (001) by molecular beam epitaxy and scanning tunneling microscopy . The images show smooth terraces and atomic steps. On some of the terraces a unique and new reconstruction is seen, resolved as square Mn tetramers in a c(4x2) structural arrangement. Two domains of the tetramer reconstruc

C. A. Sackett

It is shown that when a magnetic field is used to support neutral atoms against the gravitational force mg, the total curvature of the field magnitude B must be larger than m^2 g^2/(2 μ^2 B), where mu is the magnetic moment of the atoms. This limits the minimum confinement strength obtainable for a trapped atomic gas. It is also conjectured that the curvatur

Aveek Bid, Achyut Bora, A. K. Raychaudhuri, D. Chakravortya

We have measured the low frequency (1mHz<f<10Hz) resistance fluctuations in metallic nanowires (diameter 15nm to 200nm) in the temperature range 77K to 400K. The nanowires were grown electrochemically in polycarbonate membranes and the measurements were carried out in arrays of nanowires by retaining them in the membrane. A large fluctuation in excess of con

M. C. Fleenor, J. A. Rose, W. A. Christiansen, M. Johnston-Hollitt

We present 118 new optical redshifts for galaxies in 12 clusters in the Horologium-Reticulum supercluster (HRS) of galaxies. For 76 galaxies, the data were obtained with the Dual Beam Spectrograph on the 2.3m telescope of the Australian National University at Siding Spring Observatory. After combining 42 previously unpublished redshifts with our new sample,

Morad Masjedi, David W. Hogg, Richard J. Cool, Daniel J. Eisenstein

We present the small-scale (0.01<r<8 h^{-1} Mpc) projected correlation function w_p(r_p) and real space correlation function xi(r) of 24520 luminous early-type galaxies from the Sloan Digital Sky Survey Luminous Red Galaxy (LRG) sample (0.16<z<0.36). ``Fiber collision&#39;&#39; incompleteness of the SDSS spectroscopic sample at scales smaller than 55 arcseco

Charles D. Dermer

Gamma-ray bursts are known to be sources of high-energy gamma rays, and are likely to be sources of high-energy cosmic rays and neutrinos. Following a short review of observations of GRBs at multi-MeV energies and above, the physics of leptonic and hadronic models of GRBs is summarized. Evidence for two components in BATSE and EGRET/TASC data suggest that GR

J. S. Kalirai, P. Guhathakurta, K. M. Gilbert, D. B. Reitzel

We present spectroscopic observations of red giant branch (RGB) stars in the Andromeda spiral galaxy (M31), acquired with the DEIMOS instrument on the Keck II 10-m telescope. The three fields targeted in this study are in the M31 spheroid, outer disk, and giant southern stream. In this paper, we focus on the kinematics and chemical composition of RGB stars i

Noam Soker

I propose that some of the most luminous planetary nebulae (PNs) are actually proto-PNs, where a companion white dwarf (WD) accretes mass at a relatively high rate from the post-asymptotic giant branch star that blew the nebula. The WD sustains a continuous nuclear burning and ionizes the nebula. The WD is luminous enough to make the dense nebula luminous in

M. J. Freyberg, B. Altieri, D. Bermejo, M. P. Esquej

The scientific data collected during slews of the XMM-Newton satellite are used to construct a slew survey catalogue. This comprises of the order of 4000 sources detected in the EPIC-pn 0.2-12 keV band with exposures of less than 15s and a sky coverage of about 6300 square degrees (source density ~0.65 per square degree). Below 2 keV the sensitivity limit is

N. Przybilla, M. F. Nieva, U. Heber, C. S. Jeffery

Two evolutionary scenarios are proposed for the formation of extreme helium stars: a post-AGB star suffering from a late thermal pulse, or the merger of two white dwarfs. An identification of the evolutionary channel for individual objects has to rely on surface abundances. We present preliminary results from a non-LTE analysis of CNO, Mg and S for two uniqu

N. Przybilla, K. Butler, U. Heber, C. S. Jeffery

Quantitative analyses of extreme helium stars to date face the difficulty that theory fails to reproduce the observed helium lines in their entirety, wings and line cores. Here, we demonstrate how the issues can be resolved using state-of-the-art non-LTE line formation for these chemically peculiar objects. Two unique B-type objects are discussed in detail,

N. Przybilla, M. F. Nieva, H. Edelmann

We report on preliminary results of a hybrid non-LTE analysis of high-resolution, high-S/N spectra of the helium-rich subdwarf B star Feige49 and the helium-poor sdB HD205805. Non-LTE effects are found to have a notable impact on the stellar parameter and abundance determination. In particular the HeI lines show significant deviations from detailed balance,

P. B. Ivanov, J. C. B. Papaloizou

(abbreviated) We consider the problem of the tidal capture or circularisation from large eccentricity of a uniformly rotating object. We extend the self-adjoint formalism introduced in Papaloizou \& Ivanov 2005 (PI) to derive general expressions for the energy and angular momentum transfered when the planet or a star passes through periastron in a parabolic

T. Sakamoto, L. Barbier, S. D. Barthelmy, J. R. Cummings

We report Swift Burst Alert Telescope (BAT) observations of the X-ray Flash (XRF) XRF 050416A. The fluence ratio between the 15-25 keV and 25-50 keV energy bands of this event is 1.5, thus making it the softest gamma-ray burst (GRB) observed by BAT so far. The spectrum is well fitted by the Band function with E^{\rm obs}_{\rm peak} of 15.0_{-2.7}^{+2.3} keV.

M. Brüggen, M. Ruszkowski

The physics of the intracluster medium, in particular the values for the thermal conductivity and the viscosity are largely unknown and subject to an ongoing debate. Here, we study the effect of viscosity on the thermal state of the intracluster medium using three-dimensional cosmological simulations of structure formation. It is shown that viscosity, provid

Norbert Przybilla, Keith Butler

We evaluate the effect of variations in the electron-impact excitation cross sections on the non-LTE line formation for hydrogen in early-type stars. While the Balmer lines are basically unaffected by the choice of atomic data, the Brackett and Pfund series members allow us to discriminate between the different models. Non-LTE calculations based on the widel

A. J. Norton, J. D. Tanner

We present the first optical photometry of the counterpart to the candidate intermediate polar RX J0153.3+7446. This reveals an optical pulse period of 2333s +/- 5s. Reanalysis of the previously published ROSAT X-ray data reveals that the true X-ray pulse period is probably 1974s +/- 30s, rather than the 1414 s previously reported. Given that the previously

Morten Stejner, Jes Madsen

The gap caused by a strong electric field between the quark surface and nuclear crust of a strange star is studied in an improved model including gravity and pressure as well as electrostatic forces. The transition from gap to crust is followed in detail. The properties of the gap are investigated for a wide range of parameters assuming both color-flavor loc

M. Bureau, A. Chung

We have identified two new galaxies with gas counter-rotation (NGC1596 and NGC3203) and have confirmed similar behaviour in another one (NGC128), this using results from separate studies of the ionized-gas and stellar kinematics of a well-defined sample of 30 edge-on disc galaxies. Gas counter-rotators thus represent 10+/-5% of our sample, but the fraction c

Yakiv V. Pavlenko

We determine the carbon isotopic ratios in the atmospheres of some evolved stars in both globular clusters and the disk of our Galaxy. Analysis of 12CO and 13CO bands at 2.3 micron was carried out using fits to observed spectra of red giants and Sakurai&#39;s object (V4334 Sgr). The dependence of theoretical spectra on the various input parameters was studie

S. V. Zharikov, G. H. Tovmassian, R. Napiwotzki, R. Michel

We observed a new and poorly studied cataclysmic variable (CV) SDSS J123813.73-033933.0 to determine its classification and binary parameters. Simultaneous time-resolved photometric and spectroscopic observations were carried out to conduct period analysis and Doppler tomography mapping. From radial velocity measurements of the Ha line we determined its orbi

S. A. Petrova

Propagation of radio waves in the ultrarelativistic magnetized electron-positron plasma of pulsar magnetosphere is considered. Polarization state of the original natural waves is found to vary markedly on account of the wave mode coupling and cyclotron absorption. The change is most pronounced when the regions of mode coupling and cyclotron resonance approxi

B. W. Holwerda

Source Extractor for Dummies is a user manual for the SEXtractor (Bertin and Arnouts 1996) software package for the detection of astronomical sources in fits-files of fields. It has seen much use as a quick tool and is constantly updated with new features. This fifth installment of the user manual is to catch up with these updates and improve explanations an

A. Georgakakis, A. M. Hopkins, J. Afonso, M. Sullivan

We estimate the star-formation rates and the stellar masses of the Extremely Red objects (EROs) detected in a 180arcmin2 Ks-band survey (Ks~20mag). This sample is complemented by sensitive 1.4GHz radio observations (12micro-Jy; 1sigma rms) and multiwaveband photometric data (UBVRIJ) as part of the Phoenix Deep Survey. For bright K<19.5mag EROs in this sample

Mario C. R. D&#39;Souza, Patrick M. Motl, Joel E. Tohline, Juhan Frank

Hydrodynamical simulations of semi-detached, polytropic binary stars are presented in an effort to study the onset and stability of dynamical mass transfer events. Initial, synchronously rotating equilibrium models are constructed using a self-consistent-field technique and then evolved with an Eulerian hydrodynamics code in a fully self-consistent manner. W

Sasa Ratkovic, Madappa Prakash, James M. Lattimer

Binary mergers involving black holes and neutron stars have been proposed as major sources of gravitational waves, r--process nucleosynthesis, and gamma ray bursters. In addition, they represent an important, and possibly unique, observable that could distinguish between normal and self--bound neutron stars. These two families of stars have distinctly differ

P. D. Mininni

Planetary and stellar dynamos likely result from turbulent motions in magnetofluids with kinematic viscosities that are small compared to their magnetic diffusivities. Laboratory experiments are in progress to produce similar dynamos in liquid metals. This work reviews recent computations of thresholds in critical magnetic Reynolds number above which dynamo

Ansgar Reiners, Gibor Basri

We present the first high-resolution (R ~ 31,000) spectra of the cool sdL 2MASS0532, and what was originally identified as an early-type L subdwarf (sdL) LSR1610-0040. Our work, in combination with contemporaneous work by Cushing and Vacca, makes it clear that the latter object is more probably a mid-M dwarf with an unusual composition that gives it some sub

V. V. Tikhomirov, Y. A. Tsalkou

It is shown that, contrary to the widespread opinion, particle collisions considerably increase accretion rate from the cosmological background onto 5D primordial black holes formed during the high-energy phase of the Randall-Sundrum Type II braneworld scenario. Increase of accretion rate leads to much tighter constraints on initial primordial black hole mas

N. Laskin, G. Zaslavsky

A unified approach has been developed to study nonlinear dynamics of a 1D lattice of particles with long-range power-law interaction. A classical case is treated in the framework of the generalization of the well-known Frenkel-Kontorova chain model for the non-nearest interactions. Quantum dynamics is considered following Davydov&#39;s approach for molecular