December 2006 arXiv papers — page 12

M. J. Soto, J. L. Vicente

We show that the roots of a Weierstrass polynomial on several variables are power series with rational exponents of bounded denominators, whose Newton diagrams are contained in an S-cone. As an application, in Section 4 we deal with some topics of integral dependence of Puiseux power series.

Jean-Baptiste Butruille

We classify six-dimensional homogeneous nearly K\"{a}hler manifolds and give a positive answer to Gray and Wolf's conjecture: every homogeneous nearly K\"{a}hler manifold is a Riemannian 3-symmetric space equipped with its canonical almost Hermitian structure. The only four examples in dimension 6 are $S^3 \times S^3$, the complex projective space $\CM P^3$,

S. Baldwin, J. C. Eilbeck, J. Gibbons, Y. Ônishi

We discuss the theory of generalized Weierstrass $σ$ and $\wp$ functions defined on a trigonal curve of genus four, following earlier work on the genus three case. The specific example of the "purely trigonal" (or "cyclic trigonal") curve $y^3=x^5+λ_4 x^4 +λ_3 x^3+λ_2 x^2 +λ_1 x+λ_0$ is discussed in detail, including a list of some of the ass

Christian Pierre

The seven non euclidean geometries of the Thurston's geometrization program are proved to originate naturally from singularization morphisms and versal deformations on euclidean 3-manifolds generated in the frame of the Langlands global program. The Poincare conjecture for a 3-manifold appears as a particular case of this new approach of the Thurston&#39

Aurélien Alfonsi, Benjamin Jourdain

In this paper, we investigate the generalization of the Call-Put duality equality obtained in [1] for perpetual American options when the Call-Put payoff $(y-x)^+$ is replaced by $ϕ(x,y)$. It turns out that the duality still holds under monotonicity and concavity assumptions on $ϕ$. The specific analytical form of the Call-Put payoff only makes calculations

Aurélien Alfonsi, Benjamin Jourdain

It is well known that in models with time-homogeneous local volatility functions and constant interest and dividend rates, the European Put prices are transformed into European Call prices by the simultaneous exchanges of the interest and dividend rates and of the strike and spot price of the underlying. This paper investigates such a Call Put duality for pe

Hans Vernaeve

We show that for smooth manifolds X and Y, any isomorphism between the special algebra of Colombeau generalized functions on X, resp. Y is given by composition with a unique Colombeau generalized function from Y to X. We also identify the multiplicative linear functionals from the special algebra of Colombeau generalized functions on X to the ring of Colombe

Tatyana S. Turova, Thomas Vallier

We study a random graph model which is a superposition of the bond percolation model on $Z^d$ with probability $p$ of an edge, and a classical random graph $G(n, c/n)$. We show that this model, being a {\it homogeneous} random graph, has a natural relation to the so-called "rank 1 case" of {\it inhomogeneous} random graphs. This allows us to use the

Tolga Etgü

As an application of the construction of open books on plumbed 3-manifolds, we construct elliptic open books on torus bundles over the circle. In certain cases these open books are compatible with Stein fillable contact structures and have minimal genus.

Ludwik Dabrowski

The local index formula of Connes--Moscovici for the isospectral noncommutative geometry recently constructed on quantum SU(2) is discussed. The cosphere bundle and the dimension spectrum as well as the local cyclic cocycles yielding the index formula, are presented.

Hans Van de Vyver

Two-step hybrid methods specially adapted to the numerical integration of perturbed oscillators are obtained. The formulation of the methods is based on a refinement of classical Taylor expansions due to Scheifele [{\em Z. Angew. Math. Phys.}, {\bf 22}, 186--210 (1971)]. The key property is that those algorithms are able to integrate exactly harmonic oscilla

Denis I. Saveliev

In set theory without the axiom of regularity, we consider a game in which two players choose in turn an element of a given set, an element of this element, etc.; a player wins if its adversary cannot make any next move. Sets that are winning, i.e. have a winning strategy for a player, form a natural hierarchy with levels indexed by ordinals. We show that th

Maria Bras-Amorós, Anna de Mier

We introduce square diagrams that represent numerical semigroups and we obtain an injection from the set of numerical semigroups into the set of Dyck paths.

Ivan Marin

Motivated by examples in infinite group theory, we classify the finite groups whose subgroups can never be decomposed as direct products.

A. R. Gover

In these expository notes we draw together and develop the ideas behind some recent progress in two directions: the treatment of finite type partial differential operators by prolongation, and a class of differential complexes known as detour complexes. This elaborates on a lecture given at the IMA Summer Programme ``Symmetries and overdetermined systems of

Goldtwe Anihc, Baishi Wang

In the paper, there are new found methods to determine the range of every exceptional element in exceptional set, we can solve Twin primes problem and Goldbach Conjecture problem basically.

Kenneth S. Alexander

We consider a polymer, with monomer locations modeled by the trajectory of an underlying Markov chain, in the presence of a potential thatinteracts with the polymer when it visits a particular site 0. Disorder is introduced by having the interaction vary from one monomer to another, as a constant $u$ plus i.i.d. mean-0 randomness. There is a critical value o

Jaume Garriga, Alan H. Guth, Alexander Vilenkin

A ``bubble universe'' nucleating in an eternally inflating false vacuum will experience, in the course of its expansion, collisions with an infinite number of other bubbles. In an idealized model, we calculate the rate of collisions around an observer inside a given reference bubble. We show that the collision rate violates both the homogeneity and t

C. Bastos, O. Bertolami, N. C. Dias, J. N. Prata

We review the main features of the Weyl-Wigner formulation of noncommutative quantum mechanics. In particular, we present a $\star$-product and a Moyal bracket suitable for this theory as well as the concept of noncommutative Wigner function. The properties of these quasi-distributions are discussed as well as their relation to the sets of ordinary Wigner fu

Olaf Hohm

In this thesis we investigate the effective actions for massive Kaluza-Klein states, focusing on the massive modes of spin-3/2 and spin-2 fields. To this end we determine the spontaneously broken gauge symmetries associated to these `higher spin' states and construct the unbroken phase of the Kaluza-Klein theory. We show that for the particular backgroun

V. K. Oikonomou

The temperature inversion symmetry, for a non interacting supersymmetric ensemble, at finite volume, is studied. It is found that, the scaled free energy, $f(ξ)$, is antisymmetric under temperature inversion transformation, i.e. $f(ξ)=-ξ^{d}f(\frac{1}ξ)$. This occurs for antiperiodic bosons and periodic fermions, in the compact dimension. On the contrary, fo

Brett Altschul

Some of the best bounds on possible Lorentz violation in the electron sector come from observations of high-energy astrophysical phenomena. Using measurements of TeV inverse Compton radiation from a number of sources, we place the first bounds--at the 10^(-15) level--on seven of the electron d coefficients.

Gordon L. Kane, Piyush Kumar, David E. Morrissey, Manuel Toharia

If supersymmetry is discovered at the LHC, the measured spectrum of superpartner masses and couplings will allow us to probe the origins of supersymmetry breaking. However, to connect the collider-scale Lagrangian soft parameters to the more fundamental theory from which they arise, it is usually necessary to evolve them to higher scales. The apparent unific

Andrea Banfi, Gennaro Corcella, Mrinal Dasgupta

We study the mismatch between a full calculation of non-global single-logarithms in the large-N_c limit and an approximation based on free azimuthal averaging, and the consequent angular-ordered pattern of soft gluon radiation in QCD. We compare the results obtained in either case to those obtained from the parton showers in the Monte Carlo event generators

F. Bazzocchi, M. Fabbrichesi, P. Ullio

We discuss a minimal extension to the standard model in which there are two Higgs bosons and, in addition to the usual fermion content, two fermion doublets and one fermion singlet. The little hierachy problem is solved by the vanishing of the one-loop corrections to the quadratic terms of the scalar potential. The electro-weak ground state is therefore stab

Irinel Caprini, Jan Fischer

The renormalization-group improved finite order expansions of the QCD observables have an unphysical singularity in the Euclidean region, due to the Landau pole of the running coupling. Recently it was claimed that, by using a modified Borel representation, the leading one-chain term in a skeleton expansion of the Euclidean QCD observables is finite and cont

S. Frixione, B. R. Webber

This is the user's manual of MC@NLO 3.3. This package is a practical implementation, based upon the HERWIG event generator, of the MC@NLO formalism, which allows one to incorporate NLO QCD matrix elements consistently into a parton shower framework. Processes available in this version include the hadroproduction of single vector and Higgs bosons, vector

A. Psaker, W. Melnitchouk, A. V. Radyushkin

We extend the analysis of the deeply virtual Compton scattering process to the weak interaction sector in the generalized Bjorken limit. The virtual Compton scattering amplitudes for the weak neutral and charged currents are calculated at the leading twist within the framework of the nonlocal light-cone expansion via coordinate space QCD string operators. Us

Jiunn-Wei Chen, William Detmold, Brian Smigielski

We consider the pion matrix elements of the isoscalar and isovector combinations of the vector and tensor twist-two operators that determine the moments of the various pion generalised parton distributions. Our analysis is performed using partially-quenched chiral perturbation theory. We work in the SU(2) and SU(4|2) theories and present our results at infin

Silas R. Beane, Paulo F. Bedaque, Thomas C. Luu, Kostas Orginos

We present results of the first fully-dynamical lattice QCD determination of hyperon-nucleon scattering. One s-wave phase shift was determined for n Lambda scattering in both spin-channels at pion masses of 350, 490, and 590 MeV, and for n Sigma- scattering in both spin channels at pion masses of 490, and 590 MeV. The calculations were performed with domain-

TWQCD Collaboration, Ting-Wai Chiu, Tung-Han Hsieh

We present the first lattice results of the spectrum of exotic vector mesons extracted from the molecular and diquark-antidiquark operators, with quark fields c-q-cbar-qbar, and c-s-cbar-qbar (c-q-cbar-sbar) respectively, in lattice QCD with exact chiral symmetry. Our results suggest that X(3872) and Y(4260) are in the spectrum of QCD, with J^{PC} = 1^{++} a

Stefano Lami

The current large uncertainty on the extrapolation of the proton-proton total cross section at the LHC energy will be resolved by the precise measurement by the TOTEM experiment. Its accurate studies on the basic properties of proton-proton collisions at the maximum accelerator energy could provide a significant contribution to the understanding of cosmic ra

Tim Koslowski

This paper serves as a preparation of work that focuses on extracting cosmological sectors from Loop Quantum Gravity. We start with studying the extraction of subsystems from classical systems. A classical Hamiltonian system can be reduced to a subsystem of ''relevant observables'' using the pull-back under the Poisson-embedding of the '&

Sante Carloni, Peter K. S. Dunsby

The evolution equations for tensor perturbations in a generic scalar tensor theory of gravity are presented. Exact solution are given for a specific class of theories and Friedmann-Lemaître-Robertson-Walker backgrounds. In these cases it is shown that, although the evolution of tensor models depends on the choice of parameters of the theory, no amplification

G. Venturi

The cosmological consequences of a simple scalar field model for the generation of Newton's constant through the spontaneous breaking of scale invariance in a curved space-time are again presented and discussed. Such a model leads to a consistent description wherein the introduction of matter introduces a small perturbation on a de Sitter universe and a

Roger S. Barga, Jonathan Goldstein, Mohamed Ali, Mingsheng Hong

Event processing will play an increasingly important role in constructing enterprise applications that can immediately react to business critical events. Various technologies have been proposed in recent years, such as event processing, data streams and asynchronous messaging (e.g. pub/sub). We believe these technologies share a common processing model and d

Alexander Böhm, Carl-Christian Kanne, Guido Moerkotte

This paper gives an overview of Demaq, an XML message processing system operating on the foundation of transactional XML message queues. We focus on the syntax and semantics of its fully declarative, rule-based application language and demonstrate our message-based programming paradigm in the context of a case study. Further, we discuss optimization opportun

Paul Greenfield, Alan Fekete, Julian Jang, Dean Kuo

In this paper, we propose an approach to providing the benefits of isolation in service-oriented applications where it is not feasible to hold traditional locks for ACID transactions. Our technique, called "Promises", provides an uniform view for clients which covers a wide range of implementation techniques on the service side, all allowing the client to ch

Boris Baryshnikov, Cipri Clinciu, Conor Cunningham, Leo Giakoumakis

While there are known performance trade-offs between database page buffer pool and query execution memory allocation policies, little has been written on the impact of query compilation memory use on overall throughput of the database management system (DBMS). We present a new aspect of the query optimization problem and offer a solution implemented in Micro

Russell Sears, Catharine van Ingen

Fragmentation leads to unpredictable and degraded application performance. While these problems have been studied in detail for desktop filesystem workloads, this study examines newer systems such as scalable object stores and multimedia repositories. Such systems use a get/put interface to store objects. In principle, databases and filesystems can support s

James Hamilton

Several factors are driving high-scale deployments of large data centers built upon commodity components. These commodity clusters are far cheaper than mainframe systems of the past but they bring serious heat and power density issues. Also the high failure rate of the individual components drives significant administrative costs. This proposal outlines an a

Dmitry Lebedev, Fabien Mathieu, Laurent Viennot, Anh-Tuan Gai

This paper aims to provide insight into stability of collaboration choices in P2P networks. We study networks where exchanges between nodes are driven by the desire to receive the best service available. This is the case for most existing P2P networks. We explore an evolution model derived from stable roommates theory that accounts for heterogeneity between

Friedhelm R. Drepper

Voiced segments of speech are assumed to be composed of non-stationary acoustic objects which can be described as stationary response of a non-stationary fundamental drive (FD) process and which are furthermore suited to reconstruct the hidden FD by using a voice adapted (self-consistent) part-tone decomposition of the speech signal. The universality and rob

Slawomir Lasota, David Nowak, Yu Zhang

Software security can be ensured by specifying and verifying security properties of software using formal methods with strong theoretical bases. In particular, programs can be modeled in the framework of lambda-calculi, and interesting properties can be expressed formally by contextual equivalence (a.k.a. observational equivalence). Furthermore, imperative f

Vibhor Rastogi, Dan Suciu, Sungho Hong

We consider the privacy problem in data publishing: given a relation I containing sensitive information 'anonymize' it to obtain a view V such that, on one hand attackers cannot learn any sensitive information from V, and on the other hand legitimate users can use V to compute useful statistics on I. These are conflicting goals. We use a definition o

Vladimir A. Belyi, D. Kaya, M. Muthukumar

Solute deposits from evaporating drops with pinned contact line are usually concentrated near the contact line. The stain, or pattern, left on the substrate then consists of a single ring, commonly known as a coffee ring. Here we report on a variation of this phenomenon when periodic patterns emerge. We attribute these to phase transitions in certain solutes

R. Wehn, P. Lunkenheimer, A. Loidl

We present the results of aging experiments on a variety of glass formers, including xylitol, glycerol, propylene carbonate, and [Ca(NO3)2]0.4[KNO3]0.6 (CKN). In addition, broadband dielectric spectra of xylitol and CKN are provided. We demonstrate that, irrespective of which dielectric quantities (dielectric constant, loss and modulus) are analyzed, and irr

S. Schwieger, J. Kienert, K. Lenz, J. Lindner

Quantum mechanical calculations based on an extended Heisenberg model are compared with ferromagnetic resonance (FMR) experiments on prototype trilayer systems Ni_7/Cu_n/Co_2/Cu(001) in order to determine and separate for the first time quantitatively the sources of the temperature dependence of interlayer exchange coupling. Magnon excitations are responsibl

J. Joseph, B. Clancy, L. Luo, J. Kinast

Sound waves are observed and studied in an optically trapped degenerate Fermi gas of spin-up and spin-down atoms with magnetically tunable interactions. Measurements are made throughout the crossover region, from a weakly-interacting Fermi gas through the resonant Fermi superfluid regime to a Bose condensate of dimer molecules. The measured sound velocities

Aiqin Jiang, Neha Awasthi, Aleksey N. Kolmogorov, Wahyu Setyawan

The thermal behavior of free and alumina-supported iron-carbon nanoparticles is investigated via molecular dynamics simulations, in which the effect of the substrate is treated with a simple Morse potential fitted to ab initio data. We observe that the presence of the substrate raises the melting temperature of medium and large $Fe_{1-x}C_x$ nanoparticles ($

R. Citro, F. Romeo, M. Marinaro

We investigate the effect of Rashba spin-orbit coupling and of a tunnel barrier on the zero conduc- tance resonances appearing in a one-dimensional conducting Aharonov-Bohm (AB) ring symmet- rically coupled to two leads. The transmission function of the corresponding one-electron problem is derived within the scattering matrix approach and analyzed in the co

L. Meier, G. Salis, C. Ellenberger, E. Gini

Time-resolved Faraday rotation is used to measure the coherent electron spin precession in a GaAs/InGaAs quantum well below an interdigitated magnetized Fe grating. We show that the electron spin precession frequency can be modified by applying a gate voltage of opposite polarity to neighboring bars. A tunability of the precession frequency of 0.5 GHz/V has

Juha J. Vartiainen, Mikko Mottonen, Jukka Pekola, Antti Kemppinen

We have employed a tunable Cooper-pair transistor, the sluice, with radio frequency control to pump current over a resistive circuit. We find that the charge transferred per pumping cycle can be controlled with the resolution of a single Cooper-pair up to hundreds of pairs. The achieved nanoampere current features more than an order of magnitude improvement

A. Opitz, M. Bronner, W. Bruetting

Mixed layers of copper-phthalocyanine (p-conductive) and fullerene (n-conductive) are used for the fabrication of organic field-effect transistors (OFETs) and inverters. Regarding the electrical characteristics of these donor-acceptor blends they show ambipolar charge carrier transport, whereas devices made from only one of the materials show unipolar behavi

Bohdan Lev

A general description of elastic matter and the long-range elastic interaction is propose. The type of the far-field interaction is determined by the way of breaking in the continuum distribution of the elastic field produced by topological defects, which can present isolated inclusions. To provide an adequate description of the inter-inclusion interaction.

J. Y. Romanova, Y. A. Romanov

We consider the dynamics of electrons in semiconductor superlattices in intense multifrequency electric fields. We examine the conditions for dynamic localization and electromagnetic transparency. We investigate processes of formation, destruction and stabilization of electromagnetic transparency in biharmonic field. The stable dc fields are founded.

Ivan Naumov, Huaxiang Fu

Phase transformation in finite-size ferroelectrics is of fundamental relevance for understanding collective behaviors and balance of competing interactions in low-dimensional systems. We report a first-principles effective Hamiltonian study of vortex-to-polarization transformation in Pb(Zr$_{0.5}$Ti$_{0.5}$)O$_3$ nanoparticles, caused by homogeneous electric

M. V. Fistul, A. V. Ustinov

We report a theoretical study of the macroscopic quantum dynamics in spatially extended Josephson systems. We focus on a Josephson tunnel junction of finite length placed in an externally applied magnetic field. In such a system, electromagnetic waves in the junction are excited in the form of cavity modes manifested by Fiske resonances, which are easily obs

B. Dietz, T. Friedrich, J. Metz, M. Miski-Oglu

We experimentally investigated the decay behavior with time t of resonances near and at exceptional points, where two complex eigenvalues and also the associated eigenfunctions coalesce. The measurements were performed with a dissipative microwave billiard, whose shape depends on two parameters. The t^2-dependence predicted at the exceptional point on the ba

Bin Zhou, Shun-Qing Shen

We study the spin photogalvanic effect in two-dimensional electron system with structure inversion asymmetry by means of the solution of semiconductor optical Bloch equations. It is shown that a linearly polarized light may inject a pure spin current in spin-splitting conduction bands due to Rashba spin-orbit coupling, while a circularly polarized light may

W. Meevasana, X. J. Zhou, S. Sahrakorpi, W. S. Lee

To date, angle-resolved photoemission spectroscopy has been successful in identifying energy scales of the many-body interactions in correlated materials, focused on binding energies of up to a few hundred meV below the Fermi energy. Here, at higher energy scale, we present improved experimental data from four families of high-Tc superconductors over a wide

Hiroaki Matsueda, Sumio Ishihara

Motivated by photoinduced phase transition in manganese oxides, charge and spin dynamics induced by photoirradiation are examined. We calculate the transient optical absorption spectra of the extended double-exchange model by the density matrix renormalization group (DMRG) method. A charge-ordered insulating (COI) state becomes metallic just after photoirrad

A. Liebsch, H. Ishida

A new concept is proposed for the paramagnetic metal insulator transition in the layer perovskite Ca_{2-x}Sr_xRuO_4. Whereas the pure Sr compound is metallic up to very large Coulomb energies due to strong orbital fluctuations, structural changes induced by doping with Ca give rise to a interorbital charge transfer which makes the material extremely sensitiv

Bernhard Schulz, Ralf Siebenmorgen, Martin Haas, Endrik Kruegel

We have observed seven powerful FR2 radiogalaxies and seven quasars with the Spitzer IRS. Both samples are comparable in both, redshift range and isotropic 178 Hz luminosity. Both samples are found to have similar distributions in the luminosity ratios of Mid-IR high- and low-excitation lines ([NeV]/[NeII]), and of Mid-IR high-excitation line to radio power

Daniel Cordier, Adriano Pietrinferni, Santi Cassisi, Maurizio Salaris

Stellar evolution tracks and isochrones are key inputs for a wide range of astrophysical studies; in particular, they are essential to the interpretation of photometric and spectroscopic observations of resolved and unresolved stellar populations. We have made available to the astrophysical community a large, homogenous database of up-to-date stellar tracks

Ian S. McLean, L. Prato, Mark R. McGovern, Adam J. Burgasser

We present a sequence of high resolution (R~20,000 or 15 km/s) infrared spectra of stars and brown dwarfs spanning spectral types M2.5 to T6. Observations of 16 objects were obtained using eight echelle orders to cover part of the J-band from 1.165-1.323 micron with NIRSPEC on the Keck II telescope. By comparing opacity plots and line lists, over 200 weak fe

D. Munshi, P. Valageas, L. Van Waerbeke, A. Heavens

Weak gravitational lensing is responsible for the shearing and magnification of the images of high-redshift sources due to the presence of intervening matter. The distortions are due to fluctuations in the gravitational potential, and are directly related to the distribution of matter and to the geometry and dynamics of the Universe. As a consequence, weak g

Saurabh Jha, Adam G. Riess, Robert P. Kirshner

We present an updated version of the Multicolor Light Curve Shape method to measure distances to type Ia supernovae (SN Ia), incorporating new procedures for K-correction and extinction corrections. We also develop a simple model to disentangle intrinsic color variations and reddening by dust, and expand the method to incorporate U-band light curves and to m

Vikram V. Dwarkadas

Massive stars can significantly modify the surrounding medium during their lifetime. When the stars explode as supernovae, the resulting shock wave expands within this modified medium and not within the interstellar medium. We explore the evolution of the medium around massive stars, and the expansion of the shock wave within this medium. We then apply these

Edgar Bugaev, Peter Klimai

We calculate neutrino and photon energy spectra in extragalactic space from evaporation of primordial black holes, assuming that the power spectrum of primordial density fluctuations has a strong bump in the region of small scales. The constraints on the parameters of this bump based on neutrino and photon cosmic background data are obtained.

T. Bensby, M. S. Oey, S. Feltzing, B. Gustafsson

Using high-resolution spectra of nearby F and G dwarf stars, we have investigated the detailed abundance and age structure of the Hercules stream. We find that the stars in the stream have a wide range of stellar ages, metallicities, and element abundances. By comparing to existing samples of stars in the solar neighbourhood with kinematics typical of the Ga

R. J. Blackwell-Whitehead, H. Lundberg, G. Nave, J. C. Pickering

We report experimental oscillator strengths for 88 Ti I transitions covering the wavelength range 465 to 3892 nm, 67 of which had no previous experimental values. Radiative lifetimes for thirteen energy levels, including the low energy levels 3d2 (3F) 4s4p (3P) z5Dj, have been measured using time resolved laser induced fluorescence. Intensity calibrated Ti I

Hui-Chen Chen, Chung-Ming Ko

Star clusters are formed in molecular clouds which are believed to be the birth places of most stars. From recent observational data, Lada & Lada(2003) estimated that only 4 to 7% of the proto-clusters have survived. Many factors could cause this high infant mortality. Galactic tidal forces, close encounters with molecular clouds and shock heating are among

Francesca D'Antona, Paolo Ventura, Vittoria Caloi

The majority of the inhomogeneities in the chemical composition of Globular Cluster (GC) stars appear due to primordial enrichment. The most studied model today claims that the ejecta of Asymptotic Giant Branch (AGB) stars of high mass -those evolving during the first ~100Myr of the Clusters life- directly form a second generation of stars with abundance ano

C. Venter, O. C. de Jager

Radio, X-ray, and HESS gamma-ray observations of the Galactic Center (GC) composite supernova remnant SNR G0.9+0.1 are used to constrain a time-dependent injection model of the downstream electron spectrum responsible for the total multiwavelength spectrum. The effect of spindown power evolution aswell as nebular field evolution is employed to reproduce the

D. L. Clements, K. G. Isaak, S. C. Madden, C. Pearson

The cosmic infrared background (CIB) consists of emission from distant, dusty, star-forming galaxies. Energetically, the CIB is very important as it contains as much energy as the extragalactic optical background. The nature and evolutionary status of the objects making up the background are, however, unclear. The CIB peaks at ~150 microns, and as such is mo

Thomas Wiegelmann, Bernd Inhester, Bernhard Kliem, Gherardo Valori

CONTEXT: As the coronal magnetic field can usually not be measured directly, it has to be extrapolated from photospheric measurements into the corona. AIMS: We test the quality of a non-linear force-free coronal magnetic field extrapolation code with the help of a known analytical solution. METHODS: The non-linear force-free equations are numerically solved

Bernd Inhester

We discuss some basic principles of stereoscopy and their relevance to the reconstruction of coronal loops. The aim of the paper is to make the solar physicist familiar with basic stereoscopy principles and to give hints how they may apply to the analysis of data from the forthcoming STEREO mission. We disucss the geometry of the solar coronal stereo problem

P. Lira, M. Kishimoto, A. Robinson, S. Young

We present results from very high signal-to-noise spectropolarimetric observations of the Seyfert 1 galaxy NGC 3783. Position Angle (PA) changes across the Balmer lines show that the scatterer is resolving the Broad-Emission Line Region (BLR). A broad component seen in polarized light and located bluewards from the H$β$ line very likely corresponds to HeII$\

L. Videla, P. Lira, A. Alonso-Herrero, D. M. Alexander

We performed imaging on 49 type 2 Seyfert galaxies in 6 near- and mid-infrared bands (1-10$μ$m). We are separating the contribution of the torus from the host galaxy by radial profile fitting techniques and we will compare the observed spectral energy distributions with theoretical models of torus emission to constrain geometrical and physical parameters.

Francesca D'Antona, Anamaria Teodorescu, Paolo Ventura

We summarize the status of art of the secular evolution of low mass X-ray binaries (LMXBs) and take a close look at the orbital period distribution of LMXBs and of binary millisecond pulsars (MSP), in the hypothesis that this latter results from the LMXB evolution. The deficiency of systems below the period gap, which in cataclysmic binaries occurs between ~

P. D'Avanzo, D. Malesani, S. Campana, S. Covino

We present Chandra and VLT observations of the X-Ray Flash XRF 040812. The X-ray analysis reveals with high precision the position of a hard, fading source. A careful analysis of our I-band VLT images taken starting 17 hours after the burst led to the discovery of the optical afterglow superimposed to a bright (I=21.5) host galaxy. The optical afterglow is s

S. Covino, D. Malesani, G. Tagliaferri, S. D. Vergani

The availability of multi-wavelength high-quality data of gamma-ray burst afterglows in the Swift era, contrary to the expectations, did not allow us to fully confirm yet one of the most fundamental features of the standard afterglow picture: the presence of an achromatic break in the decaying light curve. We briefly review the most interesting cases identif

Thomas Wiegelmann, Bernd Inhester, Takashi Sakurai

Knowledge regarding the coronal magnetic field is important for the understanding of many phenomena, like flares and coronal mass ejections. Because of the low plasma beta in the solar corona the coronal magnetic field is often assumed to be force-free and we use photospheric vector magnetograph data to extrapolate the magnetic field into the corona with the

Hagai B. Perets, Clovis Hopman, Tal Alexander

We investigate the role of massive perturbers, such as giant molecular clouds or stellar clusters, in supplying low-angular momentum stars that pass very close to the central massive black hole (MBH) or fall into it. We show that massive pe rturbers can play an important role in supplying both binaries and single stars to the vicinity of the MBH. We discuss

Maxim Kramar, Bernd Inhester

Hanle-effect observations of forbidden coronal line transitions and recently also longitudinal Zeeman-effect measurements of coronal lines show quantitative signatures of the weak coronal magnetic field. The interpretation of these observations is, however, complicated by the fact that they are the result of line-of-sight integrations through the optically t

M. Razzano

We present here the current status of pulsar simulations for the Large Area Telescope, the main instrument on the GLAST mission. We present "PulsarSpectrum", a pulsar simulator that can reproduce with high detail gamma-ray emission from pulsars. "PulsarSpectrum" takes into account advanced timing effects, e.g. period changes with time, baryce

Thomas Wiegelmann, Bernd Inhester

The space mission STEREO will provide images from two viewpoints. An important aim of the STEREO mission is to get a 3D view of the solar corona. We develop a program for the stereoscopic reconstruction of 3D coronal loops from images taken with the two STEREO spacecraft. A pure geometric triangulation of coronal features leads to ambiguities because the dil

Ian McHardy, Anthony Lawson, Andrew Newsam, Alan Marscher

The X-ray emission from quasars such as 3C273 is generally agreed to arise from Compton scattering of low energy seed photons by relativistic electrons in a relativistic jet oriented close to the line of sight. However there are a number of possible models for the origin of the seed photons. In Paper I (McHardy et al 1999) we showed that the X-ray and IR var

Wei Wang

Observations of a strong and extended positron-electron annihilation line emission in the Galactic center (GC) region by the SPI/INTEGRAL are challenging to the existing models of positron sources in the Galaxy. In this paper, we study the possibility that pulsar winds from a millisecond pulsar population in the GC produce the 511 keV line. Our preliminary e

Nikos Prantzos

A few topics concerning the early chemical evolution of the Milky Way are critically discussed. In particular, it is argued that: 1) Observed abundance patterns of extremely metal poor stars (of Pop. II) do not constrain the mass range of the first generation (Pop. III) stars; the latter may well be normal massive stars (10-50 Msun) or very massive ones (140

A. Noutsos

The High Energy Stereoscopic System (H.E.S.S.) is a system of four, imaging, atmospheric Cherenkov telescopes in Namibia, designed to detect very-high-energy gamma rays above ~ 100 GeV. During 2002--2003, H.E.S.S. collected data from two, young and energetic radio pulsars: the Crab and PSR B1706-44. We searched for pulsations at the lowest energies that H.E.

Mallory S. E. Roberts, E. V. Gotthelf, Jules P. Halpern, Crystal L. Brogan

We present recent X-ray and radio observations of pulsar wind nebulae discovered in EGRET error boxes. Two XMM-Newton observations show the X-ray extent of the rapidly moving PWN associated with the variable gamma-ray source 3EG J1809-2328, and a trail coming from the new millisecond pulsar PSR J1614-2230 at high Galactic z. We also briefly discuss three PWN

Janusz Gil, George Melikidze, Bing Zhang

Thermal radiation from hot polar caps is examined in radio pulsars with drifting subpulses. It is argued that if these subpulses correspond to sparking discharges of the inner acceleration region right above the polar cap surface then a simple relationship between the observed subpulse drift rate in radio and thermal X-ray luminosity from the polar cap heate

C. Y. Hui, W. Becker

We report the discovery of an X-ray nebula associated with the nearby millisecond pulsar PSR J2124-3358. This is the first time that extended emission from a solitary millisecond pulsar is detected. The emission extends from the pulsar to the northwest by ~ 0.5 arcmin. The spectrum of the nebular emission can be modeled by a power law spectrum with photon in

S. Wedemeyer-Böhm, O. Steiner, J. Bruls, W. Rammacher

It is widely believed that the heating of the chromosphere in quiet-Sun internetwork regions is provided by dissipation of acoustic waves that are excited by the convective motions close to the top of the convection zone and in the photospheric overshoot layer. This view lately became challenged by observations suggesting that the acoustic energy flux into t

C. Y. Hui, W. Becker

Utilizing two Chandra High Resolution Camera (HRC-I) observations with an epoch separation of somewhat more than five years, we have measured the proper motion of the central compact object, RX J0822-4300, in the supernova remnant Puppis-A for the first time. The position of RX J0822-4300 is found to be different by 0.574 +/- 0.184 arcsec, implying a proper

Thomas Wiegelmann, Thomas Neukirch

AIMS: We develop an optimization principle for computing stationary MHD equilibria. METHODS: Our code for the self-consistent computation of the coronal magnetic fields and the coronal plasma uses non-force-free MHD equilibria. Previous versions of the code have been used to compute non-linear force-free coronal magnetic fields from photospheric measurements

D. R. Poelman, M. Spaans, A. G. G. M. Tielens

Context: Existing SWAS observations and future HIFI/Herschel data require a clear sense of the information content of water emission and absorption lines. Aims: Investigate wether the ground-state transition of ortho-H2O, 1_(10)-1_(01), at 557GHz can be used to measure the column density throughout an interstellar cloud. Methods: We make use of a multi-zone

Y. Urata, K. Y. Huang, Y. L. Qiu, J. Hu

Observations of the optical afterglow of GRB 041006 with the Kiso Observatory 1.05 m Schmidt telescope, the Lulin Observatory 1.0 m telescope and the Xinglong Observatory 0.6 m telescope. Three-bands (B, V and R) of photometric data points were obtained on 2004 October 6, 0.025-0.329 days after the burst. These very early multi band light curves imply the ex