December 2006 arXiv papers — page 22

Dirk Kussin, Hagen Meltzer

We describe a method for an explicit determination of indecomposable preprojective and preinjective representations for extended Dynkin quivers by vector spaces and matrices. This method uses tilting theory and the explicit knowledge of indecomposable modules over the corresponding canonical algebra of domestic type.

J. Colliander, J. Holmer, M. Visan, X. Zhang

We consider the Cauchy problem for a family of semilinear defocusing Schrödinger equations with monomial nonlinearities in one space dimension. We establish global well-posedness and scattering. Our analysis is based on a four-particle interaction Morawetz estimate giving \emph{a priori} $L^8_{t,x}$ spacetime control on solutions.

Hans-Joachim Baues, Fernando Muro

In this paper we prove the laws of Toda brackets on the homotopy groups of a connective ring spectrum and the laws of the cup-one square in the homotopy groups of a commutative connective ring spectrum.

Marco Abate, Filippo Bracci, Francesca Tovena

This paper is devoted to the study of the embeddings of a complex submanifold $S$ inside a larger complex manifold $M$; in particular, we are interested in comparing the embedding of $S$ in $M$ with the embedding of $S$ as the zero section in the total space of the normal bundle $N_S$ of $S$ in $M$. We explicitely describe some cohomological classes allowing

Grigory Garkusha, Mike Prest

Given a commutative ring R (respectively a positively graded commutative ring $A=\ps_{j\geq 0}A_j$ which is finitely generated as an A_0-algebra), a bijection between the torsion classes of finite type in Mod R (respectively tensor torsion classes of finite type in QGr A) and the set of all subsets Y\subset Spec R (respectively Y\subset Proj A) of the form Y

N. Bergeron

For abelian varieties $A$, in the most interesting cohomology theories $H^* (A)$ is the exterior algebra of $H^1(A)$. In this paper we study a weak generalization of this in the case of arithmetic manifolds associated to orthogonal or unitary groups. In this latter case recall that arithmetic manifolds associated to standard unitary groups $U(p,q)$ ($p\geq q

Gert Almkvist

Asymptotic formulas of the number of various partitions are studied, like 3-colored partitions, concave partitions, certain plane partitions, partitions without small parts, the number of p-rings.

Michael Oberguggenberger

This paper is a tutorial that demonstrates various methods from the Colombeau theory of generalized functions in the context of semilinear wave equations. The Colombeau generalized functions constitute differential algebras that contain the space of distributions. We solve the 1D-semilinear wave equation in these algebras, show how delta waves can be compute

Gert Almkvist

Sequences of traces of powers of integral matrices are characterized.The result can be used can be used in character tables of e.g. the symmetric group.

Yu. Kryakin

We find the order of Whitney's constants for oscillating functions

Tonia Ricciardi

We provide estimates for the Hölder exponent of solutions to the Beltrami equation $\dbar f=μ\de f+ν\bar{\de f}$, where the Beltrami coefficients $μ,ν$ satisfy $\||μ|+|ν|\|_\infty<1$ and $\Im(ν)=0$. Our estimates depend on the arguments of the Beltrami coefficients as well as on their moduli. Furthermore, we exhibit a class of mappings of the ``angular stret

Martin Hertweck

For finite nilpotent groups $G$ and $G^{\prime}$, and a $G$-adapted ring $S$ (the rational integers, for example), it is shown that any isomorphism between the centers of the group rings $SG$ and $SG^{\prime}$ is monomial, i.e., maps class sums in $SG$ to class sums in $SG^{\prime}$ up to multiplication with roots of unity. As a consequence, $G$ and $G^{\pri

Anders Kock

We study algebraic properties of matrices whose rows are mutual neighbours, and are also neigbours of 0 (&#34;neighbour&#34; in the sense of a certain nilpotency condition). The intended application is in synthetic differential geometry. For a square matrix of this kind, the product of the diagonal entries equals the determinant, modulo a factor n!

Martin Hertweck

Let $G$ be a finite group having a normal $p$-subgroup $N$ that contains its centralizer $\text{C}_{G}(N)$, and let $R$ be a $p$-adic ring. It is shown that any finite $p$-group of units of augmentation one in $RG$ which normalizes $N$ is conjugate to a subgroup of $G$ by a unit of $RG$, and if it centralizes $N$ it is even contained in $N$.

Milutin Dostanic, Kehe Zhu

We study the $L^p$ boundedness and find the norm of a class of integral operators induced by the reproducing kernel of Fock spaces over $C^n$.

Marcos Dajczer, Pedro A. Hinojosa, Jorge Herbert de Lira

It is proved the existence and uniqueness of Killing graphs with prescribed mean curvature in a large class of Riemannian manifolds.

Adrian Diaconu, Paul Garrett

This paper exposes the underlying mechanism for obtaining second integral moments of $GL_2$ automorphic $L$--functions over an arbitrary number field. Here, moments for $GL_2$ are presented in a form enabling application of the structure of adele groups and their representation theory. To the best of our knowledge, this is the first formulation of integral m

Shu-Yu Hsu

In this paper we will give a rigorous proof of the lower bound for the scalar curvature of the standard solution of the Ricci flow conjectured by G. Perelman. We will prove that the scalar curvature $R$ of the standard solution satisfies $R(x,t)\ge C_0/(1-t)\quad\forall x\in\Bbb{R}^3,0\le t<1$, for some constant $C_0>0$.

James C Robinson, Witold Sadowski

We consider the behaviour of weak solutions of the unforced three-dimensional Navier-Stokes equations, under the assumption that the initial condition has finite energy ($\|u\|^2=\int|u|^2$) but infinite enstrophy ($\|Du\|^2=\int|{\rm curl} u|^2$). We show that this has to be reflected in the solution for small times, so that in particular $\|Du(t)\|\to+\inf

Laurent Freidel, Jerzy Kowalski-Glikman, Sebastian Nowak

We show that free $κ$-Minkowski space field theory is equivalent to a relativistically invariant, non local, free field theory on Minkowski space-time. The field theory we obtain has in spectrum a relativistic mode of arbitrary mass $m$ and a Planck mass tachyon. We show that while the energy momentum for the relativistic mode is essentially the standard one

A. J. Hariton, Ralf Lehnert

The spacetime symmetries of classical electrodynamics supplemented with a Chern-Simons term that contains a constant nondynamical 4-vector are investigated. In addition to translation invariance and the expected three remaining Lorentz symmetries characterized by the little group of the external vector, the model possesses an additional spacetime symmetry if

V. Bardek, S. Meljanac

We analyze soliton solutions in the duality-based matrix model. There are two types of solution, a one soliton-antisoliton solution (with the constant boundary condition at infinity) and a periodic solution with an infinite number of solitons. It is shown that there is no finite number $ (n > 1) $ of solitons at finite distances in the limit when the length

Vadim V. Asadov, Oleg V. Kechkin

We study classical limit for quantum mechanics with two times and temperature, which describes a generalized dynamics of relativistic point mass. In this theory, thermodynamic time means a parameter of evolution, whereas geometric time is one of space-time coordinates. We identify world lines in this theory with geodesic lines for the same point mass in stan

Sean A. Hartnoll

It is observed that strings in AdS_5 x S^5 and membranes in AdS_7 x S^4 exhibit long range phase interactions. Two well separated membranes dragged around one another in AdS acquire phases of 2π/N. The same phases are acquired by a well separated F and D string dragged around one another. The phases are shown to correspond to both the standard and a novel ty

Holger B. Nielsen, Masao Ninomiya

We consider a very complicated system of some latticized differential equations that is considered as equations of motion for a field theory. We define macro state restrictions for such a system analogous to thermodynamical states of a system in statistical mechanics. For the case in which we have assumed adiabaticity in a generalized way which is equivalent

Mahnaz Haseeb, Samina S. Masood

We investigate temperature behavior up to two loop level in QED in the background heat bath using real time formalism. The thermal correction to the coupling constant in QED at low temperature are presented up to the two loop level. It is observed that the removal of singularities at the two loop level is only possible if the integrations of loop momenta are

Alessandro Bacchetta

The cross section for semi-inclusive deep inelastic scattering can be decomposed in terms of 18 structure functions. At low transverse momentum of the detected hadron, the structure functions can be expressed in terms of transverse-momentum-dependent parton distribution and fragmentation functions. Here, a few selected examples are illustrated and discussed.

Nikolaos E. Mavromatos, Sarben Sarkar

In this review we first discuss the string theoretical motivations for induced decoherence and deviations from ordinary quantum-mechanical behaviour; this leads to intrinsic CPT violation in the context of an extended class of quantum-gravity models. We then proceed to a description ofprecision tests of CPT symmetry and quantum mechanics using mainly neutral

B. C. Liu, B. S. Zou

Here we give our reply to the comment by Sibirtsev et al on our paper ``Mass and K-Lambda Coupling of the N*(1535)&#34;.

Robert D. Pisarski

I start with an elementary observation about the pressure in the deconfined phase of a SU(3) gauge theory without quarks. This suggests a ``fuzzy&#39;&#39; bag model for the analogous pressure in QCD, with dynamical quarks. I then sketch how the deconfined phase might be described using an effective theory of Wilson lines. To leading order in weak coupling,

F. R. Klinkhamer

Neutrinos allow for a test of the hypothesis that the fermions of the Standard Model have Fermi-point splitting, analogous to the fermionic quasi-particles of certain condensed-matter systems. If present, the corresponding Lorentz-violating terms in the Hamiltonian may provide a new source of T and CP violation in the leptonic sector, which is not directly r

Hitoshi Murayama, Yasunori Nomura

Gauge mediation of supersymmetry breaking is drastically simplified using generic superpotentials without U(1)_R symmetry by allowing metastable vacua.

D0 Collaboration, V. Abazov

A measurement of the top quark pair production cross section in proton anti-proton collisions at an interaction energy of sqrt(s)=1.96 TeV is presented. This analysis uses 405 pb-1 of data collected with the D0 detector at the Fermilab Tevatron Collider. Fully hadronic ttbar decays with final states of six or more jets are separated from the multijet backgro

V. V. Mochalov, A. M. Davidenko, A. A. Derevschikov, Y. M. Goncharenko

We present recent results of single-spin asymmetry $A_N$ measurements in $π^0$ inclusive production. Asymmetry was measured in $π^-p$ and $pp$ interactions at 40 and 70 GeV correspondingly. Significant asymmetry was observed in the polarized target fragmentation region. The results are in agreement with &#34;universal threshold&#34; of single-spin asymmetry.

V. V. Mochalov, S. V. Ivanov, V. I. Garkusha, A. S. Gurevich

PROZA-M experiment results as well the proposal of a new spin program with the use of a polarized proton beam are presented. Significant asymmetries were observed in inclusive $π^0$ production. The new program proposes to study a wealth of single- and double-spin observables in various reactions using longitudinally and transversely polarized proton beams at

C. Pagliarone

In this paper we review a selection of recent results obtained, in the area of QCD physics, from the CDF-II experiment that studies $p\bar{p}$ collisions at $\sqrt{s}$=1.96 TeV provided by the Fermilab Tevatron Collider. All results shown correspond to analysis performed using the Tevatron Run II data samples. In particular we will illustrate the progress ac

Riccardo Benini, Giovanni Montani

Starting from the Hamiltonian formulation for the inhomogeneous Mixmaster dynam- ics, we approach its quantum features through the link of the quasi-classical limit. We fix the proper operator-ordering which ensures that the WKB continuity equation overlaps the Liouville theorem as restricted to the configuration space. We describe the full quantum dynamics

Walid Hachem, Oleksiy Khorunzhiy, Philippe Loubaton, Jamal Najim

This paper adresses the behaviour of the mutual information of correlated MIMO Rayleigh channels when the numbers of transmit and receive antennas converge to infinity at the same rate. Using a new and simple approach based on Poincaré-Nash inequality and on an integration by parts formula, it is rigorously established that the mutual information converges t

Sujay Sanghavi

Rateless/fountain codes are designed so that all input symbols can be recovered from a slightly larger number of coded symbols, with high probability using an iterative decoder. In this paper we investigate the number of input symbols that can be recovered by the same decoder, but when the number of coded symbols available is less than the total number of in

Petra Berenbrink, Colin Cooper, Zengjian Hu

This paper studies broadcasting and gossiping algorithms in random and general AdHoc networks. Our goal is not only to minimise the broadcasting and gossiping time, but also to minimise the energy consumption, which is measured in terms of the total number of messages (or transmissions) sent. We assume that the nodes of the network do not know the network, a

James P. Sethna

In the past two decades or so, we have learned how to understand crackling noise in a wide variety of systems. We review here the basic ideas and methods we use to understand crackling noise - critical phenomena, universality, the renormalization group, power laws, and universal scaling functions. These methods and tools were originally developed to understa

A. P. Vieira, E. P. de Moura, L. L. Goncalves, J. M. A. Rebello

In this work we apply tools developed for the study of fractal properties of time series to the problem of classifying defects in welding joints probed by ultrasonic tecniques. We employ the fractal tools in a preprocessing step, producing curves with a considerably smaller number of points than in the original signals. These curves are then used in the clas

Marcos Rigol, Alejandro Muramatsu, Maxim Olshanii

We study the ground-state properties and nonequilibrium dynamics of hard-core bosons confined in one-dimensional lattices in the presence of an additional periodic potential (superlattice) and a harmonic trap. The dynamics is analyzed after a sudden switch-on or switch-off of the superlattice potential, which can bring the system into insulating or superflui

H. Lin, E. S. Bozin, S. J. L. Billinge, J. Androulakis

The average and local structures of the (PbTe)1-x(PbS)x system of thermoelectric materials has been studied using the Rietveld and atomic pair distribution function (PDF) methods. Samples with 0:25 < x are macroscopically phase separated. Phase separation was suppressed in a quenched x = 0:5 sample which, nonetheless, exhibited a partial spinodal decompositi

Levente J. Klein, Donald E. Savage, Mark A. Eriksson

Transport measurements at cryogenic temperatures through a few electron top gated quantum dot fabricated in a silicon/silicon-germanium heterostructure are reported. Variations in gate voltage induce a transition from an isolated dot toward a dot strongly coupled to the leads. In addition to Coulomb blockade, when the dot is strongly coupled to the leads, we

J. L. Xu, M. van Schilfgaarde

We use the ab initio local-density approximation (LDA) to study of exchange interactions and Tc of Ga1&#8722;xMnxAs grown in digitally doped structures. We analyze the crystallographic dependence of exchange interactions predicted by the LDA in terms of the Mn t2 and e levels, and explain the origin of the antiferromagnetic contribution to the total exchange

Aparna Baskaran, James W. Dufty, J. Javier Brey

In the preceding paper, linear response methods have been applied to obtain formally exact expressions for the parameters of Navier-Stokes order hydrodynamics. The analysis there is general, applying to both normal and granular fluids with a wide range of collision rules. Those results are specialized here to the case of smooth, inelastic hard spheres with c

Amir Aghamohammadi, Mohammad Khorrami

The most general local Markovian stochastic model is investigated, for which it is known that the evolution equation is the Fokker-Planck equation. Special cases are investigated where uncorrelated initial states remain uncorrelated. Finally, stochastic one-dimensional fields with local interactions are studied that have kink-solutions.

A. Serquis, G. Serrano, S. Moreno, ; L. Civale

The use of MgB2 in superconducting applications still awaits for the development of a MgB2-based material where both current-carrying performance and critical magnetic field are optimized simultaneously. We achieved this by doping MgB2 with double-wall carbon nanotubes (DWCNT) as a source of carbon in polycrystalline samples. The optimum nominal DWCNT conten

David Parker, Peter Thalmeier

There is still significant debate about the symmetry of the order parameter in the heavy-fermion superconductor UPd$_{2}$Al$_{3}$, with proposals for cos(k3), cos(2k3), sin(k3),and exp(iϕ) sin(k3). Here we analyze the tunneling spectroscopy of this compound and demonstrate that the experimental results by Jourdan et al are inconsistent with the last two orde

Christoph Sohrmann, Rudolf A. Roemer

We numerically investigate the interplay of disorder and electron-electron interactions in the integer quantum Hall effect. In particular, we focus on the behaviour of the electronic compressibility as a function of magnetic field and electron density. We find manifestations of non-linear screening and charging effects around integer filling factors, consist

D. A. Knyazev, O. E. Omelyanovskii, V. M. Pudalov, I. S. Burmistrov

We report on studies of the magnetoresistance in strongly correlated 2D electron system in Si in the critical regime, in the close vicinity of the 2D metal-insulator transition. We performed self-consistent comparison of our data with solutions of two equations of the cross-over renormalization group (CRG) theory which describes temperature evolutions of the

Rok Zitko, Janez Bonca

We study the spin-charge separation in a Kondo-like model for an impurity with a spin and a charge (isospin) degree of freedom coupled to a single conduction channel (the ``spin-charge&#39;&#39; Kondo model). We show that the spin and charge Kondo effects can occur simultaneously at any coupling strength. In the continuum (wide-band or weak coupling) limit,

Jorge Kurchan

The Fluctuation Relation for a stationary state, kept at constant energy by a deterministic thermostat - the Gallavotti-Cohen Theorem -- relies on the ergodic properties of the system considered. We show that when perturbed by an energy-conserving random noise, the relation follows trivially for any system at finite noise amplitude. The time needed to achiev

I. S. Burmistrov, N. M. Chtchelkatchev

We present analysis of the cross-over behavior of disordered interacting two-dimensional electron systems in the parallel magnetic field. Using the so-called cross-over one-loop renormalization group equations for the resistance and electron-electron interaction amplitudes we qualitatively explain experimentally observed transformation of the temperature dep

C. Vignat, A. Plastino

We advance scale-invariance arguments for systems that are governed (or approximated) by a $q-$Gaussian distribution, i.e., a power law distribution with exponent $Q=1/(1-q); q \in \mathbb{R}$. The ensuing line of reasoning is then compared with that applying for Gaussian distributions, with emphasis on dimensional considerations. In particular, a Gaussian s

Rene Windiks, Erich Wimmer, Leonid Pourovskii, Silke Biermann

Structural and electronic properties of the alpha- and gamma-phases of cerium sesquisulfide, Ce2S3, are examined by first-principles calculations using the GGA+U extension of density functional theory. The strongly correlated f-electrons of Ce are described by a Hubbard-type on-site Coulomb repulsion parameter. A single parameter of $U^/prime$=4 eV yields ex

Verónica I. Marconi

A detailed numerical study on the directed motion of ac-driven vortices and antivortices in 2D Josephson junction arrays (JJA) with an asymmetric periodic pinning potential is reported. Dc-voltage rectification shows a strong dependence on vortex density as well as an inversion of the vortex flow direction with ac amplitude for a wide range of vortex density

A. J. Zaleski, M. Nyk, W. Strek

The synthesis, morphology and magnetization measurements of GaN nanoceramics obtained under high pressure are reported. In particular the effect of grain size on magnetic properties of GaN nanopowders and nanoceramics was investigated. It was found that for the GaN nanoceramic characterized by the stronger deformation of nanocrystalline grains the diamagneti

F. P. Mancini, P. Sodano, A. Trombettoni

We investigate the properties of free bosons hopping on a star-comb network, discussing the single-particle spectrum and the main thermodynamic equilibrium properties: Bose-Einstein critical temperature, fraction of condensate, and spatial boson distribution. We find an enhancement of the critical temperature with respect to other inhomogeneous networks.

Jean-Noël Fuchs, Pascal Lederer

We suggest that a magnetic-field-induced Peierls instability accounts for the recent experiment of Zhang et al. in which unexpected quantum Hall plateaus were observed at high magnetic fields in graphene on a substrate. This Peierls instability leads to an out-of-plane lattice distortion resulting in a charge density wave (CDW) on sublattices A and B of the

Yukio Saito, Takeshi Sugimori, Hiroyuki Hyuga

Stochastic aspects of chemical reaction models related to the Soai reactions as well as to the homochirality in life are studied analytically and numerically by the use of the master equation and random walk model. For systems with a recycling process, a unique final probability distribution is obtained by means of detailed balance conditions. With a nonline

Uma Divakaran, Amit Dutta

We study a random fiber bundle model with tips of the fibers placed on a graph having co-ordination number 3. These fibers follow local load sharing with uniformly distributed threshold strengths of the fibers. We have studied the critical behaviour of the model numerically using a finite size scaling method and the mean field critical behaviour is establish

Yukio Saito, Hiroyuki Hyuga

Theoretical models and rate equations relevant to the Soai reaction are reviewed. It is found that in a production of chiral molecules from an achiral substrate autocatalytic processes can induce either enantiomeric excess (ee) amplification or chiral symmetry breaking. Former terminology means that the final ee value is larger than the initial value but dep

Moshe Elitzur

Observations give strong support for the unification scheme of active galactic nuclei. Clumpiness of the toroidal obscuration is crucial for explaining the IR observations and has significance consequences for AGN classification: type 1 and type 2 viewing is an angle-dependent probability, not an absolute property. The broad line region (BLR) and the dusty t

P. Kharb, C. O&#39;Dea, S. Baum, R. Daly

We have observed a sample of 13 large, powerful Fanaroff-Riley type II radio galaxies with the Very Large Array in multiple configurations and at multiple frequencies. We have combined our measurements of spectral indices, rotation measures and structural parameters such as arm-length ratios, axial ratios and misalignment angles, with similar data from the l

Hai Fu, Alan Stockton

Luminous extended emission-line regions (EELRs) on kpc scales surround a substantial fraction of steep-spectrum radio-loud QSOs. Although their existence has been known for over three decades, there are still major uncertainties on the physical processes responsible for their complex morphology and kinematics. We are obtaining deep integral field spectroscop

Anca Constantin, Michael S. Vogeley

We discuss here the spatial clustering of Seyferts and LINERs and consequences for their central engines. We show that Seyferts are less clustered than LINERs, and that this difference is not driven by the morphology-density relation, but it is related to the difference in clustering as a function of level of activity in these systems and the amount of fuel

J. E. Kessler-Silacci, C. P. Dullemond, J. -C. Augereau, B. Merin

Recent results indicate that the grain size and crystallinity inferred from observations of silicate features may be correlated with spectral type of the central star and/or disk geometry. In this paper, we show that grain size, as probed by the 10 um silicate feature peak-to-continuum and 11.3-to-9.8 um flux ratios, is inversely proportional to log L_star.

A. Frankowski, S. Jancart, A. Jorissen

The comparison of the proper motions constructed from positions spanning a short (Hipparcos) or long time (Tycho-2) makes it possible to uncover binaries with periods of the order of or somewhat larger than the short time span, since the unrecognised orbital motion will then add to the proper motion. A list of candidate proper motion binaries is constructed

W. M. Liu, P. M. Hinz, M. R. Meyer, E. E. Mamajek

We present the results of 10 micron nulling interferometric observations of 13 Herbig Ae stars using the Magellan I (Baade) and the MMT 6.5 m telescopes. A portion of the observations was completed with the adaptive secondary at the MMT. We have conclusively spatially resolved 3 of the 13 stars, HD 100546, AB Aur, and HD 179218, the latter two recently resol

A. Kashlinsky, R. G. Arendt, J. Mather, S. H. Moseley

We discuss interpretation of the cosmic infrared background (CIB) anisotropies detected by us recently in the Spitzer IRAC based measurements. The fluctuations are approximately isotropic on the sky consistent with their cosmological origin. They remain after removal of fairly faint intervening sources and must arise from a population which has a strong CIB

D. M. Crenshaw, S. B. Kraemer

We present an analysis of UV and optical spectra of NGC 4151 obtained at high spectral and angular resolutions with the Hubble Space Telescope&#39;s (HST&#39;s) Space Telescope Imaging Spectrograph (STIS). We identify a kinematic component of the emission lines that has a width of 1170 km/s (FWHM), intermediate between those from the broad and narrow (emissi

A. Kashlinsky, R. G. Arendt, J. Mather, S. H. Moseley

Cosmic infrared background fluctuations may contain measurable contribution from objects inaccessible to current telescopic studies, such as the first stars and other luminous objects in the first Gyr of the Universe&#39;s evolution. In an attempt to uncover this contribution we have analyzed the GOODS data obtained with the Spitzer IRAC instrument, which ar

P. P. Avelino, C. J. A. P. Martins, J. Menezes, R. Menezes

We describe the results of the largest and most accurate three-dimensional field theory simulations of domain wall networks with junctions. We consider a previously introduced class of models which, in the limit of large number $N$ of coupled scalar fields, approaches the so-called `ideal&#39; model (in terms of its potential to lead to network frustration).

P. M. Ogle, R. R. J. Antonucci, D. Whysong

Spitzer Infrared Spectrograph (IRS) observations of 3C radio galaxies and quasars shed new light on the nature of the central engines of AGN. Emission from silicate dust obscuring the central engine can be used to estimate the bolometric luminosity of an AGN. Emission lines from ions such as O IV and Ne V give another indication of the presence or lack of a

Jason H. Steffen, Eric Agol

In a transiting planetary system, the presence of a second planet will cause the time interval between transits to vary. These transit timing variations (TTV) are particularly large near mean-motion resonances and can be used to infer the orbital elements of planets with masses that are too small to detect by any other means. I present the results of a study

A. M. S. Smith, A. Collier Cameron, D. J. Christian, W. I. Clarkson

A recent study demonstrated that there is significant covariance structure in the noise on data from ground-based photometric surveys designed to detect transiting extrasolar planets. Such correlation in the noise has often been overlooked, especially when predicting the number of planets a particular survey is likely to find. Indeed, the shortfall in the nu

James M. Lattimer, Maddapa Prakash

We investigate how current and proposed observations of neutron stars can lead to an understanding of the state of their interiors and the key unknowns: the typical neutron star radius and the neutron star maximum mass. A theoretical analysis of neutron star structure, including general relativistic limits to mass, compactness, and spin rates is made. We con

Zdenek Stuchlik, Petr Slany, Gabriel Torok

Change of sign of the LNRF-velocity gradient has been found for accretion discs orbiting rapidly rotating Kerr black holes with spin a > 0.9953 for Keplerian discs and a > 0.99979 for marginally stable thick discs. Aschenbach (2004) has identified the maximal rate of change of the orbital velocity within the &#34;humpy&#34; profile with a locally defined cri

A. Frankowski, A. Jorissen

A unified evolutionary scheme that includes post-AGB systems, barium stars, symbiotics, and related systems, explaining their similarites as well as differences. Can we construct it? We compare these various classes of objects in order to construct a consistent picture. Special attention is given to the comparison of the barium pollution and symbiotic phenom

D. Gotz, M. Falanga, F. Senziani, A. De Luca

The supergiant fast X-ray transient IGR J08408-4503 was discovered by INTEGRAL on May 15, 2006, during a bright flare. The source shows sporadic recurrent short bright flares, reaching a peak luminosity of 10^36 erg s^-1 within less than one hour. The companion star is HD 74194, an Ob5Ib(f) supergiant star located at 3 kpc in the Vela region. We report the l

M. I. Stodilka, S. Z. Malynych

In this paper, the physical conditions within the inhomogeneous solar atmosphere have been reconstructed by means of solving the inverse problem of Non Local Thermodynamic Equilibrium (NLTE) radiative transfer. The profiles of $λ=523.42$ nm FeI spectral line of high spatial and time resolution were used as observational data. The velocity field has been stud

A. C. Fabian

Accreting black holes often show iron line emission in their X-ray spectra. When this line emission is very broad or variable then it is likely to originate from close to the black hole. The theory and observations of such broad and variable iron lines are briefly reviewed here. In order for a clear broad line to be found, one or more of the following have t

Irina A. Yegorova, Paolo Salucci

We find a new Tully-Fisher-like relation for spiral galaxies holding at different galactocentric radii. This Radial Tully-Fisher (RTF) relation allows us to investigate the distribution of matter in the optical regions of spiral galaxies. This relation, applied to three different samples of rotation curves of spiral galaxies, directly proves that: 1) the rot

M. M. Dworetsky, Rosemary Willatt

The binary nature of the bright (V = 4.2 mag) Mercury-Manganese star Phi Her has been known since 1976 and it was considered a low-amplitude single-lined SB. In a recent study we found evidence for lines of the secondary star. Other recent results from interferometry provide a good measure of the light ratio. It is very plausible that the secondary is a late

R. Cornelisse, J. Casares, D. Steeghs, A. D. Barnes

Phase-resolved high resolution optical spectroscopy has revealed narrow N III and He II emission lines from the soft X-ray transient Aquila X-1 during its 2004 outburst that move as a function of the orbit consistent with the phasing of the donor star. Under the assumption that these lines come from the irradiated side of the donor star, we can constrain its

S. Pilling, R. Neves, A. C. F. Santos, H. M. Boechat-Roberty

The presence of methyl alcohol or methanol (CH$_3$OH) in several astrophysical environments has been characterized by its high abundance that depends on both the production rate and the destruction rate. In the present work, the photoionization and photodissociation processes of methanol have been experimentally studied, employing soft X-ray photons (100-310

I. Strateva, W. N. Brandt, M. Eracleous, G. Garmire

We summarize the optical, UV, and X-ray properties of double-peaked emitters -- AGN with double-peaked Balmer emission lines believed to originate in the AGN accretion disk. We focus on the X-ray spectroscopic results obtained from a new sample of the 16 broadest Balmer line AGN observed with Chandra and Swift.

P. Mohr, F. Kaeppeler, R. Gallino

The nucleosynthesis of nature&#39;s rarest isotope 180Ta depends sensitively on the temperature of the astrophysical environment because of depopulation of the long-living isomeric state via intermediate states to the short-living ground state by thermal photons. Reaction rates for this transition have been measured in the laboratory. These ground state rate

A. C. Fabian, J. S. Sanders

It is well known that the radiative cooling time of the hot X-ray emitting gas in the cores of most clusters of galaxies is less than 10^10 yr. In many clusters the gas temperature also drops towards the centre. If we draw a causal connection between these two properties then we infer the presence of a cooling flow onto the central galaxy. High spectral reso

K. Werner, T. Nagel, T. Rauch, V. Suleimanov

We describe our recent progress in modeling supernova-fallback disks and neutron star (NS) atmospheres. We present a first detailed spectrum synthesis calculation of a SN-fallback disk composed of iron. We assume a thin disk with a radial structure described by the alpha-disk model. The vertical structure and emission spectrum are computed self-consistently

Pasquale Blasi, Elena Amato, Damiano Caprioli

Particle acceleration at non-relativistic shocks can be very efficient, leading to the appearance of non-linear effects due to the dynamical reaction of the accelerated particles on the shock structure and to the non-linear amplification of the magnetic field in the shock vicinity. The value of the maximum momentum $p_{max}$ in these circumstances cannot be

A. D. Romeo, N. R. Napolitano, G. Covone, J. Sommer-Larsen

N--body + hydrodynamical simulations of formation and evolution of galaxy groups in a LambdaCDM cosmology have been performed. The properties of the galaxy populations in 12 groups are here discussed, with focus on the colour-magnitude relation in both normal and fossil groups.

Dominik J. Schwarz

The size and time of formation of the first gravitationally bound objects in the Universe is set by the microphysical properties of the dark matter. It is argued that observations seem to favour cold and thermal candidates for the main contribution to the dark matter. For that type of dark matter, the size and time of formation of the first halos is determin

K. É. Gabányi, S. Britzen, T. P. Krichbaum, U. Bach

In radio bands, the study of compact radio sources can be affected by propagation effects through the Interstellar Medium. These are usually attributed to the presence of turbulent intervening plasma along the line of sight. Here, two of such effects are presented. The line of sight of B 2005+403 passes through the heavily scattered region of Cygnus, which c

P. Mucciarelli, L. Zampieri, A. Treves, R. Turolla

We present an analysis of recent XMM-Newton and HST archive data of the ultraluminous X-ray source NGC 1313 X-2. Quasi-simultaneous observations taken with XMM-Newton, HST and VLT allow us to study both the X-ray light curve and its correlation with the optical emission of the two proposed ULX counterparts. At the end of December 2003 the source experienced

Tsevi Mazeh, Omer Tamuz, Shay Zucker

Sys-Rem (Tamuz, Mazeh & Zucker 2005) is a detrending algorithm designed to remove systematic effects in a large set of lightcurves obtained by a photometric survey. The algorithm works without any prior knowledge of the effects, as long as they appear in many stars of the sample. This paper presents the basic principles of Sys-Rem and discusses a parameteriz

T. D. Kinman, C. Cacciari, A. Bragaglia, A. Buzzoni

Space motions are given for 38 RR Lyrae (RRL) stars and 79 blue horizontal branch (BHB) stars in a ~200 deg2 area around the North Galactic Pole (NGP) using a homogeneous distance scale consistent with (m-M)0=18.52 for the LMC. The kinematics of the 26 RRL and 52 BHB stars in the 10.4 cubic kpc volume that have Z<8 kpc are not homogeneous. Our BHB sample (li

Duncan A. Forbes, Robert Proctor, Jay Strader, Jean P. Brodie

Here we test the idea that new globular clusters (GCs) are formed in the same gaseous (&#34;wet&#34;) mergers or interactions that give rise to the young stellar populations seen in the central regions of many early-type galaxies. We compare mean GC colors with the age of the central galaxy starburst. The red GC subpopulation reveals remarkably constant mean