The soft X-ray excess AGN RE J2248-511

We model the spectral energy distribution of the ultrasoft broad-line AGN RE J2248-511 with Comptonised accretion disc models. These are able to reproduce the steep optical and ultrasoft X-ray slopes, and the derived black hole mass is consistent with independent mass estimates. This AGN displays properties of both broad and narrow line Seyfert 1 galaxies, but we conclude that it is intrinsically a `normal' Seyfert 1 viewed at high inclination angle.Comment: 4 pages, 1 figure. MG10 Proceeding

Integral relations and the adiabatic expansion method for 1+2 reactions above the breakup threshold: Helium trimers with soft-core potentials

The integral relations formalism introduced in \cite{bar09,rom11}, and designed to describe 1+$N$ reactions, is extended here to collision energies above the threshold for the target breakup. These two relations are completely general, and in this work they are used together with the adiabatic expansion method for the description of 1+2 reactions. The neutron-deuteron breakup, for which benchmark calculations are available, is taken as a test of the method. The s-wave collision between the $^4$He atom and $^4$He$_2$ dimer above the breakup threshold and the possibility of using soft-core two-body potentials plus a short-range three-body force will be investigated. Comparisons to previous calculations for the three-body recombination and collision dissociation rates will be shown.Comment: To be published in Physical Review

Molecular gas associated with IRAS 10361-5830

We analyze the distribution of the molecular gas and the dust in the molecular clump linked to IRAS 10361-5830, located in the environs of the bubble-shaped HII region Gum 31 in the Carina region, with the aim of determining the main parameters of the associated material and investigating the evolutionary state of the young stellar objects identified there. Using the APEX telescope, we mapped the molecular emission in the J=3-2 transition of three CO isotopologues, 12CO, 13CO and C18O, over a 1.5' x 1.5' region around the IRAS position. We also observed the high density tracers CS and HCO+ toward the source. The cold dust distribution was analyzed using submillimeter continuum data at 870 \mu\ obtained with the APEX telescope. Complementary IR and radio data at different wavelengths were used to complete the study of the ISM. The molecular gas distribution reveals a cavity and a shell-like structure of ~ 0.32 pc in radius centered at the position of the IRAS source, with some young stellar objects (YSOs) projected onto the cavity. The total molecular mass in the shell and the mean H$_2$ volume density are ~ 40 solar masses and ~(1-2) x 10$^3$ cm$^{-3}$, respectively. The cold dust counterpart of the molecular shell has been detected in the far-IR at 870 \mu\ and in Herschel data at 350 \mu. Weak extended emission at 24 \mu\ from warm dust is projected onto the cavity, as well as weak radio continuum emission. A comparison of the distribution of cold and warm dust, and molecular and ionized gas allows us to conclude that a compact HII region has developed in the molecular clump, indicating that this is an area of recent massive star formation. Probable exciting sources capable of creating the compact HII region are investigated. The 2MASS source 10380461-5846233 (MSX G286.3773-00.2563) seems to be responsible for the formation of the HII region.Comment: Accepted in A&A. 11 pages, 10 Postscript figure

The formation of spiral arms and rings in barred galaxies

In this and in a previous paper (Romero-Gomez et al. 2006) we propose a theory to explain the formation of both spirals and rings in barred galaxies using a common dynamical framework. It is based on the orbital motion driven by the unstable equilibrium points of the rotating bar potential. Thus, spirals, rings and pseudo-rings are related to the invariant manifolds associated to the periodic orbits around these equilibrium points. We examine the parameter space of three barred galaxy models and discuss the formation of the different morphological structures according to the properties of the bar model. We also study the influence of the shape of the rotation curve in the outer parts, by making families of models with rising, flat, or falling rotation curves in the outer parts. The differences between spiral and ringed structures arise from differences in the dynamical parameters of the host galaxies. The results presented here will be discussed and compared with observations in a forthcoming paper.Comment: 16 pages, 13 figures, accepted in A&A. High resolution version available at http://www.oamp.fr/dynamique/pap/merce.htm

Dynamics of Entanglement Transfer Through Multipartite Dissipative Systems

We study the dynamics of entanglement transfer in a system composed of two initially correlated three-level atoms, each located in a cavity interacting with its own reservoir. Instead of tracing out reservoir modes to describe the dynamics using the master equation approach, we consider explicitly the dynamics of the reservoirs. In this situation, we show that the entanglement is completely transferred from atoms to reservoirs. Although the cavities mediate this entanglement transfer, we show that under certain conditions, no entanglement is found in cavities throughout the dynamics. Considering the entanglement dynamics of interacting and non-interacting bipartite subsystems, we found time windows where the entanglement can only flow through interacting subsystems, depending on the system parameters.Comment: 8 pages, 11 figures, publishe in Physical Review

General integral relations for the description of scattering states using the hyperspherical adiabatic basis

In this work we investigate 1+2 reactions within the framework of the hyperspherical adiabatic expansion method. To this aim two integral relations, derived from the Kohn variational principle, are used. A detailed derivation of these relations is shown. The expressions derived are general, not restricted to relative $s$ partial waves, and with applicability in multichannel reactions. The convergence of the ${\cal K}$-matrix in terms of the adiabatic potentials is investigated. Together with a simple model case used as a test for the method, we show results for the collision of a $^4$He atom on a \dimer dimer (only the elastic channel open), and for collisions involving a $^6$Li and two $^4$He atoms (two channels open).Comment: Accepted for publication in Physical Review

Variational description of continuum states in terms of integral relations

Two integral relations derived from the Kohn Variational Principle (KVP) are used for describing scattering states. In usual applications the KVP requires the explicit form of the asymptotic behavior of the scattering wave function. This is not the case when the integral relations are applied since, due to their short range nature, the only condition for the scattering wave function $\Psi$ is that it be the solution of $(H-E)\Psi=0$ in the internal region. Several examples are analyzed for the computation of phase-shifts from bound state type wave functions or, in the case of the scattering of charged particles, it is possible to obtain phase-shifts using free asymptotic conditions. As a final example we discuss the use of the integral relations in the case of the Hyperspherical Adiabatic method.Comment: 34 pages, 7 figures, accepted in Phys. Rev.

The quantum Rabi model in a superfluid Bose-Einstein condensate

We propose a quantum simulation of the quantum Rabi model in an atomic quantum dot, which is a single atom in a tight optical trap coupled to the quasiparticle modes of a superfluid Bose-Einstein condensate. This widely tunable setup allows to simulate the ultrastrong coupling regime of light-matter interaction in a system which enjoys an amenable characteristic timescale, paving the way for an experimental analysis of the transition between the Jaynes-Cummings and the quantum Rabi dynamics using cold-atom systems. Our scheme can be naturally extended to simulate multi-qubit quantum Rabi models. In particular, we discuss the appearance of effective two-qubit interactions due to phononic exchange, among other features.Comment: Improved version and references adde