October 2006 arXiv papers — page 5

R. Campoamor-Stursberg

After classifying indecomposable quasi-classical Lie algebras in low dimension, and showing the existence of non-reductive stable quasi-classical Lie algebras, we focus on the problem of obtaining sufficient conditions for a quasi-classical Lie algebras to be the contraction of another quasi-classical algebra. It is illustrated how this allows to recover the

A. de Souza Dutra, A. C. Amaro de Faria

In this work we extend the range of applicability of a method recently introduced where coupled first-order nonlinear equations can be put into a linear form, and consequently be solved completely. Some general consequences of the present extension are then commented.

L. V. Belvedere

The main objective of this paper was to obtain the two-dimensional order and disorder thermal operators using the Thermofield Bosonization formalism. We show that the general property of the two-dimensional world according with the bosonized Fermi field at zero temperature can be constructed as a product of an order and a disorder variables which satisfy a d

Manuela Kulaxizi

We elucidate the connection between the N=1 beta-deformed SYM theory and noncommutativity. Our starting point is the T-duality generating transformation involved in constructing the gravity duals of both beta-deformed and noncommutative gauge theories. We show that the two methods can be identified provided that a particular submatrix of the O(3,3,R) group e

Bernard L. G. Bakker, Jorn K. Boomsma, Chueng-Ryong Ji

We present a light-front calculation of the box diagram in Yukawa theory. The covariant box diagram is finite for the case of spin-1/2 constituents exchanging spin-0 particles. In light-front dynamics, however, individual time-ordered diagrams are divergent. We analyze the corresponding light-front singularities and show the equivalence between the light-fro

Matthias R Gaberdiel, Terry Gannon

The charges of the twisted branes for strings on the group manifold SU(n)/Z_d are determined. To this end we derive explicit (and remarkably simple) formulae for the relevant NIM-rep coefficients. The charge groups of the twisted and untwisted branes are compared and found to agree for the cases we consider.

Theodore N. Tomaras

The assumption that our Universe is close to a late time fixed point of the equations of cosmology, leads to a modification of the latter to include energy exchange between the matter and the "dark energy". The brane-world scenario provides a natural set-up for such energy exchange and is analyzed in detail. The role of brane-bulk energy exchange and

Ben Gripaios, Stephen M. West

We present a supersymmetric model of electroweak symmetry-breaking exhibiting improved naturalness, wherein the stop mass can be pushed beyond the reach of the Large Hadron Collider without unnatural fine tuning. This implies that supersymmetry may still solve the hierarchy problem, even if it eludes detection at the LHC.

B. I. Ermolaev, M. Greco, S. I. Troyan

Total resummation of leading logarithms of x contributing to the spin-dependent structure function g_1 ensures its steep rise at small x. DGLAP lacks such a resummation. Instead, the DGLAP expressions for g_1 are complemented with special phenomenological fits for the initial parton densities. The singular factors x^{-α} in the fits mimic the resummation and

Pierre van Baal

We review the recent progress made in understanding instantons at finite temperature (calorons) with non-trivial holonomy, and their monopole constituents as relevant degrees of freedom for the confined phase.

J. P. Lansberg, B. Pire, L. Szymanowski

We use general relations between the Transition Distribution Amplitudes (TDAs), entering the description of the p -> pi0 transition, and the proton Distribution Amplitudes (DAs) in the soft-pion limit to estimate the size of the amplitude for backward electroproduction of pi0 at large Q2.

Steven Rimmer

A minimal particle content supersymmetric model with a discrete Z_3 symmetry, allowing lepton number violating terms, is studied. Within this model, the neutrino masses and mixing can be generated by lepton number violating couplings. Choosing parameters which correctly describe both the masses and mixing in the neutrino sector, we consider their repercussio

Thomas Konstandin

In this talk, electroweak baryogenesis in the nMSSM is discussed. We focus on differences compared to the MSSM. We conclude that electroweak baryogenesis in the nMSSM is rather generic. Still, sfermions of the first two generations are required to be heavy to evade constraints from electric dipole moments.

Roberto Anglani

Specific heat and neutrino emissivity due to direct URCA processes for quark matter in the color superconductive Larkin-Ovchinnikov-Fulde-Ferrell (LOFF) phase of Quantum-Chromodynamics have been evaluated. The cooling rate of simplified models of compact stars with a LOFF matter core is estimated.

R. Thomas, T. Hilger, S. Zschocke, B. Kampfer

Spectral properties of hadrons in nuclear matter are treated in the framework of QCD sum rules. The influence of the ambient strongly interacting medium is encoded in various condensates. Especially, the structure of different four-quark condensates and their density dependencies in light quark systems are exemplified for the omega meson and the nucleon.

J. R. Pelaez, G. Rios

By using unitarized two-loop Chiral Perturbation Theory partial waves to describe pion-pion scattering we find that the dominant component of the lightest scalar meson does not follow the q-qbar dependence on the number of colors that, in contrast, is obeyed by the lightest vectors. The method suggests that a subdominant q-qbar component of the f_0(600) poss

Tai-Fu Feng, Xue-Qian Li, Wen-Gan Ma, Jian-Xiong Wang

In this work, we present a new strategy to investigate the possibility of direct detection of the ambient neutralino matter at accelerator. We calculate the cross sections for both elastic and inelastic scattering processes of the dark matter particles with the beam particles at $e^+e^-$ and hadron colliders.

Johan Bijnens, Niclas Danielsson

We introduce photons in Partially Quenched Chiral Perturbation Theory and calculate the resulting electromagnetic loop-corrections at NLO for the charged meson masses and decay constants. We also present a numerical analysis to indicate the size of the different corrections. We show that several phenomenologically relevant quantities can be calculated consis

Tereza Mendes, Attilio Cucchieri

Three-dimensional N-vector spin models may define universality classes for such diverse phenomena as i) the superfluid transition in liquid helium (currently investigated in the micro-gravity environment of the Space Shuttle) and ii) the transition from hadronic matter to a quark-gluon plasma, studied in heavy-ion collisions at the laboratories of Brookhaven

A. Cucchieri, R. B. Frigori, T. Mendes, A. Mihara

We propose a new local algorithm for the thermalization of n-vector spin models, which can also be used in the numerical simulation of SU(N) lattice gauge theories. The algorithm combines heat-bath (HB) and micro-canonical updates in a single step -- as opposed to the hybrid overrelaxation method, which alternates between the two kinds of update steps -- whi

Jean-Francois Grivaz

Recent searches for physics beyond the standard model at the Tevatron are reported, with emphasis on supersymmetry.

Marc-Thierry Jaekel, Serge Reynaud

The study of post-Einsteinian metric extensions of general relativity (GR), which preserve the metric interpretation of gravity while considering metrics which may differ from that predicted by GR, is pushed one step further. We give a complete description of radar ranging and Doppler tracking in terms of the time delay affecting an electromagnetic signal tr

A. N. Alexandrov, I. B. Vavilova, V. I. Zhdanov

We discuss theoretical formalisms concerning with experimental verification of General Relativity (GR). Non-metric generalizations of GR are considered and a system of postulates is formulated for metric-affine and Finsler gravitational theories. We consider local observer reference frames to be a proper tool for comparing predictions of alternative theories

Chandrasekher Mukku, Swadesh M. Mahajan, Bindu A. Bambah

We generalize the Raychaudhuri equation for the evolution of a self gravitating fluid to include an Abelian and non-Abelian hybrid magneto fluid at a finite temperature. The aim is to utilize this equation for investigating the dynamics of astrophysical high temperature Abelian and non-Abelian plasmas.

Petarpa Boonserm

In this thesis four separate problems in general relativity are considered, divided into two separate themes: coordinate conditions and perfect fluid spheres. Regarding coordinate conditions we present a pedagogical discussion of how the appropriate use of coordinate conditions can lead to simplifications in the form of the spacetime curvature -- such tricks

Istvan Szita, Andras Lorincz

In this paper we propose a method that learns to play Pac-Man. We define a set of high-level observation and action modules. Actions are temporally extended, and multiple action modules may be in effect concurrently. A decision of the agent is represented as a rule-based policy. For learning, we apply the cross-entropy method, a recent global optimization al

Alireza Bayesteh, Amir Keyvan Khandani

In this paper, a downlink communication system, in which a Base Station (BS) equipped with $M$ antennas communicates with $N$ users each equipped with $K$ receive antennas, is considered. An efficient suboptimum algorithm is proposed for selecting a set of users in order to maximize the sum-rate throughput of the system. For the asymptotic case when $N$ tend

Dele Oluwade

The notion of 'presentation', as used in combinatorial group theory, is applied to coded character sets(CCSs) - sets which facilitate the interchange of messages in a digital computer network(DCN) . By grouping each element of the set into two portions and using the idea of group presentation(whereby a group is specified by its set of generators and

Thierry Cachat

We give a new simple proof of the decidability of the First Order Theory of (omega^omega^i,+) and the Monadic Second Order Theory of (omega^i,<), improving the complexity in both cases. Our algorithm is based on tree automata and a new representation of (sets of) ordinals by (infinite) trees.

Fuchun Liu, Daowen Qiu, Hongyan Xing, Zhujun Fan

Recently, the diagnosability of {\it stochastic discrete event systems} (SDESs) was investigated in the literature, and, the failure diagnosis considered was {\it centralized}. In this paper, we propose an approach to {\it decentralized} failure diagnosis of SDESs, where the stochastic system uses multiple local diagnosers to detect failures and each local d

Rajiv Ranjan, Aaron Harwood, Rajkumar Buyya

Grid superscheduling requires support for efficient and scalable discovery of resources. Resource discovery activities involve searching for the appropriate resource types that match the user&#39;s job requirements. To accomplish this goal, a resource discovery system that supports the desired look-up operation is mandatory. Various kinds of solutions to thi

Gus Gutoski

This paper has been withdrawn by the author due to errors.

M. F. Calhoun, C. Hsieh, V. Podzorov

The photo-induced electron and hole transfer across the semiconductor-dielectric interface in trap dominated p-type organic field-effect transistors (OFETs) has been investigated. It has been observed that the transfer of electrons into the dielectric results in a decrease of the field-effect mobility of polarons, suggesting that additional shallow traps are

V. M. Loktev, V. M. Turkowski

The superconducting properties of a recently proposed phenomenological model for a weakly doped antiferromagnet are analyzed, taking into account fluctuations of the phase of the order parameter. In this model, we assume that the doped charge carriers can&#39;t move out of the antiferromagnetic sublattice they were introduced. This case corresponds to the fr

Javier von Stecher, Chris H. Greene

A method is introduced to renormalize the zero-range interaction for use in mean-field and many-body theory, starting from two-body calculations. The density-renormalized delta-function interaction is then applied using mean-field theory to a two-component fermion gas, and compared with diffusion Monte Carlo simulations and conventional mean-field calculatio

P. Roura-Bas, V. Vildosola, A. M. Llois

The unusual and interesting physical properties of rare earth intemetallic compounds have their origin in the combination of strongly correlated 4f states and their hybridization with the conduction electron sea, which gives rise to their complex low temperature Kondo behavior. In particular, Ce compounds are very sensitive to the crystalline and chemical en

Rolf Lortz, Christoph Meingast, Alexandre I. Rykov, Setsuko Tajima

Of the many different kinds of glassy states found in nature, spin glasses and structural glasses (e.g. normal window glass) have probably received the most attention. One of the central questions concerning the glassy state is whether the &#34;glass&#34; is a distinct thermodynamic phase from the &#34;liquid&#34; phase. It is believed that this may actually

Francesc Malet, Martí Pi, Manuel Barranco, Enrico Lipparini

We have investigated the dipole charge- and spin-density response of few-electron two-dimensional concentric nanorings as a function of the intensity of a perpendicularly applied magnetic field. We show that the dipole response displays signatures associated with the localization of electron states in the inner and outer ring favored by the perpendicularly a

M. D. Shattuck

We present experimental evidence for a first-order freezing/melting phase transition in a nonequilibrium system -- an oscillated two-dimensional isobaric granular fluid. The steady-state transition occurs between a gas and a crystal and is characterized by a discontinuous change in both density and temperature. It is suppressed if the number of particles is

F. Rullier-Albenque, H. Alloul, Cyril Proust, P. Lejay

We have studied in fields up to 60T the variation of the transverse magnetoresistance (MR) of underdoped YBCO6.6 crystals either pure or with Tc reduced down to 3.5K by electron irradiation. We evidence that the normal state MR is restored above a threshold field H&#39;c(T), which is found to vanish at T&#39;c>>Tc. In the pure YBCO6.6 sample a 50 Tesla field

L. P. Gor&#39;kov, P. D. Grigoriev

The unusual phase has been recently observed in the organic material (TMTSF)$_{2}$PF$_{6}$, where superconductivity (SC) coexists with spin-density wave (SDW) in the pressure interval $p_{c1}<p<p_{c}$ below the first order transition into SC or normal metal phase. Assuming that the coexistence takes place on the microscopic scale, we consider the properties

V. R. Misko, F. M. Peeters

In mesoscopic superconducting disks vortices form shell structures as recently observed in Nb disks. We study the dynamics of such vortices, driven by an external current I_0, in a Corbino setup. At very low I_0, the system exhibits rigid body rotation while at some critical current I_c,i vortex shells rotate separately with angular velocities omega_i. This

R. C. Rai, J. Cao, S. Brown, J. L. Musfeldt

We use a combination of optical spectra, first principles calculations, and energy dependent magneto-optical measurements to elucidate the electronic structure and to study the phase diagram of Ni$_3$V$_2$O$_8$. We find a remarkable interplay of magnetic field and optical properties that reveals additional high magnetic field phases and an unexpected electro

M. M. Mahmoodian, M. V. Entin

A one-dimensional system with two $δ$-like barriers or wells bi-chromaticaly oscillating at frequencies $ω$ and $2ω$ is considered. The alternating signal leads to the direct current across the structure (even in a symmetric system). The properties of this quantum pump are studied in a wide range of the system parameters.

V. A. Vdovenkov

Physical foundations of adiabatic and nonadiabatic electronics of materials are considered in this article. It is shown the limitation of adiabatic approach to electronics of materials. It is shown that nonadiabatic physical properties of solid materials (hyperconductivity, superconductivity, thermal superconductivity and phonon drag of electrons at Debye&#3

I. Galanakis, Ph. Mavropoulos

Half-metallic Heusler alloys are amongst the most promising materials for future magnetoelectronic applications. We review some recent results on the electronic properties of these compounds. The origin of the gap in these half-metallic alloys and its connection to the magnetic properties are well understood. Changing the lattice parameter shifts slightly th

Ewa Gudowska-Nowak, Bartlomiej Dybiec, Henrik Flyvbjerg

The non-selective voltage activated cation channel from the human red cells, which is activated at depolarizing potentials, has been shown to exhibit counter-clockwise gating hysteresis. We have analyzed the phenomenon with the simplest possible phenomenological models by assuming $2\times 2$ discrete states, i.e. two normal open/closed states with two diffe

Bartlomiej Dybiec, Ewa Gudowska-Nowak

The constructive role of non-Gaussian random fluctuations is studied in the context of the passage over the dichotomously switching potential barrier. Our attention focuses on the interplay of the effects of independent sources of fluctuations: an additive stable noise representing non-equilibrium external random force acting on the system and a fluctuating

A. I. Olemskoi

Within the framework of generalized combinatorial approach, the complexity is determined for infinite set of self-similar hierarchical ensembles. This complexity is shown to increase with strengthening of the hierarchy coupling to the value, which decreases with growth of both scattering of this coupling and non-extensivity parameter.

Y. L. Loh, E. W. Carlson

We present an efficient algorithm for calculating the properties of Ising models in two dimensions, directly in the spin basis, without the need for mapping to fermion or dimer models. The algorithm gives numerically exact results for the partition function and correlation functions at a single temperature on any planar network of N Ising spins in O(N^{3/2})

Alberto Rosso, Pierre Le Doussal, Kay Joerg Wiese

We compute numerically the sequence of successive pinned configurations of an elastic line pulled quasi-statically by a spring in a random bond (RB) and random field (RF) potential. Measuring the fluctuations of the center of mass of the line allows to obtain the functional renormalization group (FRG) functions at the depinning transition. The universal form

P. Roura-Bas V. Vildosola A. M. Llois

Among the Cerium compounds, the heavier monochalcogenides CeY (Y=S,Se,Te) of cerium provide a class of compounds which together with the heavier monopnictides CeX (X=N,P,As,Sb,Bi) exhibit extremely interesting physical properties. The hybridization of the partially delocalized f-electrons seems to be responsible for the unusual properties, in particular the

M. Eckstein, M. Kollar, M. Potthoff, D. Vollhardt

The paramagnetic phase diagram of the Hubbard model with nearest-neighbor (NN) and next-nearest-neighbor (NNN) hopping on the Bethe lattice is computed at half-filling and in the weakly doped regime using the self-energy functional approach for dynamical mean-field theory. NNN hopping breaks the particle-hole symmetry and leads to a strong asymmetry of the e

Herbert Vinck-Posada, Boris A. Rodriguez, P. S. S. Guimaraes, Alejandro Cabo

We show that the combined effect of photon emission and Coulomb interactions may drive an exciton-polariton system towards a dynamical coherent state, even without phonon thermalization or any other relaxation mechanism. Exact diagonalization results for a finite system (a multilevel quantum dot interacting with the lowest energy photon mode of a microcavity

Sergey V. Lotkhov, Vladimir A. Krupenin, Alexander B. Zorin

The dc transport properties of long arrays of small Al Josephson junctions, biased through on-chip Cr resistors, are studied. The IV-characteristics show a large Coulomb threshold for current as well as negative-slope regions indicating the regime of autonomous Bloch oscillations up to rather high frequencies of f = I/2e ~1 GHz, comparable to those reported

Vayujeet Gokhale, Xiao Meng Peng, Juhan Frank

We describe the evolution of double degenerate binary systems, consisting of components obeying the zero temperature mass radius relationship for white dwarf stars, from the onset of mass transfer to one of several possible outcomes including merger, tidal disruption of the donor, or survival as a semi-detached AM CVn system. We use a combination of analytic

Olga Mena, Irina Mocioiu, Chris Quigg

The black hole at the center of the galaxy is a powerful lens for supernova neutrinos. In the very special circumstance of a supernova near the extended line of sight from Earth to the galactic center, lensing could dramatically enhance the neutrino flux at Earth and stretch the neutrino pulse.

Philippe Amram, Chantal Balkowski, Claudia Mendes de Oliveira, Henri Plana

Nearby Compact Groups of Galaxies (CGs) are very complex systems, tracing their history is a challenge (e.g. Stephan&#39;s Quintet). The presence of a diffuse X-rays emission that often peaks in the center of CGs shows that CGs are bound structures, they show numerous signs of interaction but their lifetime in much longer than their crossing times. Hickson C

R. Colistete, R. Giostri

The type Ia supernovae observational data is one of the most important in observational cosmology nowadays. Here we present the first public version of BETOCS (BayEsian Tools for Observational Cosmology using SNe Ia), which is a powerful and high productivity tool aimed to help the theoretical physicist community investigate cosmological models using type Ia

Caroline D&#39;Angelo, Roman R. Rafikov

Precision timing is the key ingredient of ongoing pulsar-based gravitational wave searches and tests of general relativity using binary pulsars. The conventional approach to timing explicitly assumes that the radio emitting region is located at the center of the pulsar, while polarimetric observations suggest that radio emission is in fact produced at altitu

W. H. T. Vlemmings, H. E. Bignall, P. J. Diamond

We present observations of the 22 GHz water megamasers in the circumnuclear disk of NGC 3079 obtained with the Green Bank Telescope. The data are analyzed for circular polarization due to the Zeeman-induced splitting of the water maser lines. No circular polarization is detected and we derive a 1 sigma upper limit of 11 mG for the toroidal magnetic field at

Roderik A. Overzier, George K. Miley, Holland C. Ford

We present deep observations taken with the HST Advanced Camera for Surveys of the central massive galaxy in a forming cluster at z=2.2. The galaxy hosting the powerful radio source MRC 1138-262 is associated with one of the most extensive merger systems known in the early universe. Our HST/ACS image shows many star-forming galaxies merging within a ~200 kpc

G. K. Miley, R. A. Overzier, A. W. Zirm, H. C. Ford

We present a deep image of the radio galaxy MRC 1138-262 taken with the Hubble Space Telescope (HST) at a redshift of z = 2.2. The galaxy is known to have properties of a cD galaxy progenitor and be surrounded by a 3 Mpc-sized structure, identified with a protocluster. The morphology shown on the new deep HST/ACS image is reminiscent of a spider&#39;s web. M

Yutaka Fujita, Tsunehiko N. Kato, Nobuhiro Okabe

The Weibel instability could be responsible for the generation of magnetic fields in various objects such as gamma-ray bursts, jets from active galactic nuclei, and clusters of galaxies. Using numerical simulations, the development of the Weibel instability at a temperature gradient is studied. It is found that current sheets are first generated at the gradi

Debora Sijacki, Volker Springel

We study the imprints of AGN feedback and physical viscosity on the properties of galaxy clusters using hydrodynamical simulation models carried out with the TreeSPH code GADGET-2. Besides self-gravity of dark matter and baryons, our approach includes radiative cooling and heating processes of the gas component and a multiphase model for star formation and S

John A. Peacock, Peter Schneider, George Efstathiou, Jonathan R. Ellis

ESO and ESA agreed to establish a number of Working Groups to explore possible synergies between these two major European astronomical institutions. This Working Group's mandate was to concentrate on fundamental questions in cosmology, and the scope for tackling these in Europe over the next ~15 years. One major resulting recommendation concerns the provisio

J. E. Chambers

In the core-accretion model, gas-giant planets form solid cores which then accrete gaseous envelopes. Tidal interactions with disk gas cause a core to undergo inward type-I migration in 10^4 to 10^5 years. Cores must form faster than this to survive. Giant planets clear a gap in the disk and undergo inward type-II migration in <10^6 years if observed disk ac

J. Garcia-Rojas, C. Esteban

The origin of the abundance discrepancy in nebulae is one of the key problems in the physics of photoionized nebulae. In this work we have analized a sample of Galactic and extragalactic H II regions where the abundance discrepancy have been measured, and we discuss the two main scenarios proposed to explain such discrepancy: temperature fluctuations over th

Manuel Linares, Michiel van der Klis, Rudy Wijnands

We report on the X-ray aperiodic timing analysis of two accreting millisecond pulsars: XTE J1807-294 and IGR J00291+5934. On the one hand, we discovered in XTE J1807-294 seven pairs of simultaneous kilohertz quasi-periodic oscillations (kHz QPOs) separated in frequency by nearly the spin frequency of the neutron star. This confirms the suspected dichotomy in

L. Prisinzano, F. Damiani, G. Micela, I. Pillitteri

Mechanisms regulating the evolution of pre-main sequence stars can be understood by studying stellar properties such as rotation, disk accretion, internal mixing and binarity. To investigate such properties, we studied a sample of 332 candidate members of the massive and populous star forming region NGC 6530. We want to select cluster members by using differ

Pierre Chanial, Hector Flores, Bruno Guiderdoni, David Elbaz

IRAS observations show the existence of a correlation between the infrared luminosity Lir and dust temperature Td in star-forming galaxies, in which larger Lir leads to higher dust temperature. The Lir-Td relation is commonly seen as reflecting the increase in dust temperature in galaxies with higher star formation rate. Even though the correlation shows a s

E. D. Grundstrom, J. L. Blair, D. R. Gies, W. Huang

We report on a three year spectroscopic monitoring program of the H-alpha emission in the massive X-ray binary LS I +65 010 = 2S 0114+650, which consists of a B-supergiant and a slowly rotating X-ray pulsar. We present revised orbital elements that yield a period of P=11.5983 +/- 0.0006 d and confirm that the orbit has a non-zero eccentricity e=0.18 +/- 0.05

A. Franceschini, M. Vaccari, S. Berta, G. Rodighiero

The Spitzer Space Telescope is devoting a significant fraction of the observing time to multi-wavelength cosmological surveys of different depths in various low-background sky regions. Several tens of thousand mid-IR galaxies have been detected over a wide interval of redshifts. A progressively clearer picture of galaxy evolution is emerging, which emphasize

N. R. Ikhsanov

Accretion of interstellar material by an isolated neutron star is discussed. The point I address here is the interaction between the accretion flow and the stellar magnetosphere. I show that the interchange instabilities of the magnetospheric boundary under the conditions of interest are basically suppressed. The entry of the material into the magnetosphere

G. Worseck, L. Wisotzki

We report on our recent detection of the transverse proximity effect of 4 foreground quasars near Q0302-003 (z=3.285) as a local hardness fluctuation in the spectral shape of the intergalactic UV radiation field, found by correlating the HI Lyαabsorption with the corresponding HeII Lyαabsorption. We argue that the spectral hardness is a sensitive physical me

Yurii Pidopryhora, Felix J. Lockman, Joseph C. Shields

While studying extraplanar neutral hydrogen in the disk-halo transition of the inner Galaxy we have discovered what appears to be a huge superbubble centered around l ~ 30 deg, whose top extends to latitudes > 25 deg at a distance of about 7 kpc. It is detected in both HI and Halpha. Using the Green Bank Telescope of the NRAO, we have measured more than 220,

Jesper Rasmussen, Jesper Sommer-Larsen, Kristian Pedersen, Sune Toft

Models of disk galaxy formation commonly predict the existence of an extended reservoir of hot gas surrounding massive spirals at low redshift. As a test of these models, we have obtained X-ray and optical data of the two massive edge-on spirals NGC 5746 and NGC 5170, in order to investigate the amount and origin of hot gas in their disks and halos. Chandra

Lara Sidoli, Ada Paizis, Angela Bazzano, Sandro Mereghetti

The X-ray burster 4U1850-087, located in the globular cluster NGC6712, is an ultracompact binary likely harbouring a degenerate companion.The source has been observed with INTEGRAL several times, during the monitoring of the Galactic plane, with an unprecedented exposure time. The broad-band spectrum (2-100 keV; INTEGRAL together with a quasi-simultaneous XM

C. Sanchez Contreras, D. Le Mignant, R. Sahai, A. Gil de Paz

We present high-angular resolution images of the post-AGB nebula IRAS18276-1431 (also known as OH17.7-2.0) obtained with the Keck II Adaptive Optics (AO) system in its Natural Guide Star (NGS) mode in the Kp, Lp, and Ms near-infrared bands. We also present supporting optical F606W and F814W HST images as well as interferometric observations of the 12CO(J=1-0

Lara Sidoli, Ada Paizis, Sandro Mereghetti

The hard X-ray source IGRJ11215-5952, discovered with INTEGRAL during a brief outburst in 2005, has been proposed as a new member of the class of Supergiant Fast X-ray Transients. Analysing archival INTEGRAL observations of the source field,we have discovered two previously unnoticed outbursts (in July 2003 and in May 2004),spaced by intervals of ~330 days,

J. H. Croston, R. P. Kraft, M. J. Hardcastle

Shock heating by radio jets is potentially an important process in a range of environments, as it will increase the entropy of the heated gas. Although this process is expected to occur in the most powerful radio-loud AGN, strong shocks have so far only been detected in nearby low-power radio galaxies. Here we discuss X-ray detections of strong shocks in nea

A. Tarchi, P. Castangia, C. Henkel, K. M. Menten

We present preliminary results of an interferometric study of the water megamaser in the merger system Arp299. This system is composed of two main sources: IC694 and NGC3690. There is clear evidence that most of the water maser emission is associated with the nucleus of the latter, confirming the presence of an optically obscured AGN as previously suggested

M. I. Kudryavtsev, S. I. Svertilov, V. V. Bogomolov

The long-term observations of the Galactic Centre as well as the Galactic anti-Centre regions in hard X-rays (10-300 keV) were made in experiments on board Prognoz-9 satellite and &#34;Mir&#34; orbital station (GRIF experiment). Some transient pulsars including A0535+262, GS1722-36, 4U1145-619, A1118-615, EXO2030+37, Sct X-1, SAX J2103.5+4545, IGR 16320-4751

Jose Gaite, Alvaro Dominguez

There is evidence of a scale-invariant matter distribution up to scales over 10 Megaparsecs. We review scaling (fractal or multifractal) models of large scale structure and their observational evidence. We conclude that the dynamics of cosmological structure formation seems to be driven to a multifractal attractor. This supports previous studies, which we re

S. I. Stepanov

Non-uniformities of plasma and magnetic field are known to cause electric currents in plasma. Electron density gradient causes diffusion current, electron temperature gradient - thermocurrent, gradient of magnetic field module - gradient current, curvature of magnetic field lines - centrifugal current. Being independent of electric field, the currents of non

A. -L. Melchior, F. Combes, A. Gould

We present a new determination of the surface brightness of our Galaxy at the Solar Neighbourhood as observed from outside the Galaxy. We rely on various existing optical and infra-red surveys to obtain a multiwavelength estimate. On the one hand, scattered light does not contribute significantly to the surface brightness. On the other hand, optical and infr

B. De Marco, M. Cappi, M. Dadina, G. G. C. Palumbo

We present the analysis of X-ray spectral varability made on a sample of 7 Seyfert 1 bright galaxies, using XMM-Newton data. From the &#34;XMM-Newton Science Archive&#34; we selected those bright Seyfert 1 showing one or more prominent flares in their 2-10 keV light curves. For each of them we extracted spectra in 3 different time intervals: before, during a

S. Jordan, R. Aznar Cuadrado, R. Napiwotzki, H. M. Schmid

Current estimates for white dwarfs with fields in excess of 1MG are about 10%; according to our first high-precision circular-polarimetric study of 12 bright white dwarfs with the VLT (Aznar Cuadrado et al. 2004) this number increases up to about 25% in the kG regime. With our new sample of 10 white dwarf observations (plus one sdO star) we wanted to improve

Stefan Jordan

The Gaia data will help to improve the construction of a luminosity function for the disk and the halo and will provide a more accurate determination of the age of our solar neighborhood. Moreover, reliable stellar dynamical investigations of the disk and halo components will be possible. For the first time it will be possible to test the mass-radius relatio

P. Vaisanen, M. Juvela, K. Mattila, J. K. Kotilainen

We present results from an on-going follow-up campaign of far-infrared sources detected as part of our ISOPHOT Cosmic IR Background project. Fields have been imaged in the optical and near-infrared, and we find at least a third of the FIR targets areas to contain a bright and nearby star-forming galaxy. We also explore the largely neglected possibility that

Gian Luigi Granato

In this invited contribution I review the justifications for the attempts, currently very popular, to include in semi-analytic models of galaxy formation prescriptions to describe the mutual link between the star formation and nuclear activity in galaxies, which has been for surprisingly long time neglected.

M. Diaz Trigo, A. N. Parmar, J. Miller, E. Kuulkers

We report on two simultaneous XMM-Newton and INTEGRAL observations of the microquasar GRO J1655-40 during the 2005 outburst when the source was in its high-soft state. The 0.3-200 keV spectra are complex with an overall continuum which may be modeled using an absorbed blackbody together with a weak, steep, power-law component. In addition, there is evidence

D. J. Price, J. J. Monaghan

In this paper we describe an adaptive softening length formalism for collisionless N-body and self-gravitating Smoothed Particle Hydrodynamics (SPH) calculations which conserves momentum and energy exactly. This means that spatially variable softening lengths can be used in N-body calculations without secular increases in energy. The formalism requires the c

Alexander V. Krivov, Martina Queck, Torsten Löhne, Miodrag Srem{č}evi{ć}

The azimuthal substructure observed in some debris disks, as exemplified by epsilon Eridani, is usually attributed to resonances with embedded planets. In a standard scenario, the Poynting-Robertson force, possibly enhanced by the stellar wind drag, is responsible for the delivery of dust from outer regions of the disk to locations of external mean-motion pl

L. F. Xing, J. R. Shi, J. Y. Wei

Surface lithium abundance and rotation velocity can serve as powerful and mutually complementary diagnostics of interior structure of stars. So far, the processes responsible for the lithium depletion during pre-main sequence evolution are still poorly understood. We investigate whether a correlation exists between equivalent widths of Li (EW(Li)) and rotati

Ing-Guey Jiang, M. Duncan, D. N. C. Lin

More than 100 extrasolar planets have been discovered since 1990s. Different from the solar system, these planets&#39; orbital eccentricities cover a huge range from 0 to 0.7. Incidently, the first Kuiper Belt Object was discovered in 1992. Thus, an interesting and important question will be whether extrasolar planetary systems could have structures like Kui

Vikram V. Dwarkadas

We review the effects of winds from massive O and B stars on the surrounding medium over the various stages of stellar evolution. Furthermore we discuss some of the implications for SNe and GRB evolution within this wind-blown medium.

J. D. Hague, B. R. Becker, M. S. Gold, J. A. J. Matthews

Two separate statistical tests are applied to the AGASA and preliminary Auger Cosmic Ray Energy spectra in an attempt to find deviation from a pure power-law. The first test is constructed from the probability distribution for the maximum event of a sample drawn from a power-law. The second employs the TP-statistic, a function defined to deviate from zero wh

Valeri N. Kotov, Oleg P. Sushkov, M. B. Silva Neto, L. Benfatto

We show that, due to the weak ferromagnetism of La$_{2-x}$Sr$_x$CuO$_4$, an external magnetic field leads to a dimensional crossover 2D $\to$ 3D for the in-plane transport. The crossover results in an increase of the hole&#39;s localization length and hence in a dramatic negative magnetoresistance in the variable range hopping regime. This mechanism quantita

Daniel G. Davis, Ben Wieland

When G is a profinite group and H and K are closed subgroups, with H normal in K, it is not known, in general, how to form the iterated homotopy fixed point spectrum (Z^{hH})^{hK/H}, where Z is a continuous G-spectrum and all group actions are to be continuous. However, we show that, if G=G_n, the extended Morava stabilizer group, and Z=L_{K(n)}(E_n \wedge X