On the contribution of ULXs to stellar feedback: an intermediate mass black hole candidate and the population of ULXs in the low-metallicity starburst galaxy ESO 338-4

X-ray radiation from accreting compact objects is an important part of stellar feedback. The metal-poor galaxy ESO 338-4 has experienced vigorous starburst during the last 40 Myr and contains some of the most massive super star clusters in the nearby Universe. Given its starburst age and its star-formation rate, ESO 338-4 is one of the most efficient nearby manufactures of neutron stars and black holes, hence providing an excellent laboratory for feedback studies. We compared X-ray images and spectra obtained by XMM-Newton and Chandra telescopes with integral field spectroscopic VLT MUSE observations in the optical to constrain the nature of strong X-ray emitters. X-ray observations uncover three ultraluminous X-ray sources (ULXs) in ESO 338-4. The brightest among them, ESO 338~X-1, has X-ray luminosity in excess of 10^{40} erg/s. We speculate that ESO 338-4 is powered by accretion on an intermediate-mass (~300Msun) black hole. We show that X-ray radiation from ULXs and hot superbubbles strongly contributes to HeII ionization and general stellar feedback in this template starburst galaxy.Comment: A&A, in pres

Hypersonic Bose–Einstein condensates in accelerator rings

© 2019, The Author(s), under exclusive licence to Springer Nature Limited. Some of the most sensitive and precise measurements—for example, of inertia1, gravity2 and rotation3—are based on matter-wave interferometry with free-falling atomic clouds. To achieve very high sensitivities, the interrogation time has to be very long, and consequently the experimental apparatus needs to be very tall (in some cases reaching ten or even one hundred metres) or the experiments must be performed in microgravity in space4–7. Cancelling gravitational acceleration (for example, in atomtronic circuits8,9 and matter-wave guides10) is expected to result in compact devices with extended interrogation times and therefore increased sensitivity. Here we demonstrate smooth and controllable matter-wave guides by transporting Bose–Einstein condensates (BECs) over macroscopic distances. We use a neutral-atom accelerator ring to bring BECs to very high speeds (16 times their sound velocity) and transport them in a magnetic matter-wave guide for 15 centimetres while fully preserving their internal coherence. The resulting high angular momentum of more than 40,000ħ per atom (where ħ is the reduced Planck constant) gives access to the higher Landau levels of quantum Hall states, and the hypersonic velocitiesachieved, combined with our ability to control potentials with picokelvin precision, will facilitate the study of superfluidity and give rise to tunnelling and a large range oftransport regimes of ultracold atoms11–13. Coherent matter-wave guides are expected to enable interaction times of several seconds in highly compact devices and lead to portable guided-atom interferometers for applications such as inertial navigation and gravity mapping

Exploring the Kibble-Zurek mechanism in a secondary bifurcation

We present new experimental results on the quenching dynamics of an extended thermo-convective system (a network array of approximately 100 convective oscillators) going through a secondary subcritical bifurcation. We characterize a dynamical phase transition through the nature of the domain walls (1D-fronts) that connect the basic multicellular pattern with the new oscillating one. Two different mechanisms of the relaxing dynamics at the threshold are characterized depending on the crossing rate $\mu=\left.\frac{d\varepsilon}{dt}\right|_{\varepsilon=0}$ of the quenched transition. From the analysis of fronts, we show that these mechanisms follow different correlation length scales $\xi \sim \mu^{-\sigma}$. Below a critical value $\mu_c$, a slow response dynamics yields a spatiotemporal coherent front with weak coupling between oscillators. Above $\mu_c$, for rapid quenches, defects are trapped at the front with a strong coupling between oscillators, similarly to the Kibble-Zurek mechanism in quenched phase transitions. These defects, pinned to the fronts, yield a strong decay of the correlation length

Sistema de gestión de energía para microrredes basado en control predictivo

En este artículo se presenta un sistema de gestión de energía para microrredes a partir de un control Predictivo basado en Modelos (MPC), el cual tiene como tarea la optimización de las operaciones de una microrred, al tiempo que cumple una serie de restricciones de funcionamiento. Para ello, el problema ha sido formulado empleando Programación Lineal Entera-Mixta (MILP), la cual ha sido resuelta de manera eficiente. Se han estudiado diferentes escenarios, comparando el MPC con una estrategia fija y se han calculado costes de funcionamiento e inversión, mostrando finalmente los resultados.Los autores quieren agradecer a la Universitat Jaume I y a la Generalitat Valenciana el apoyo recibido y materializado en los proyectos P11B2013-34 y GV/2014/117 respectivamente

Frozen dynamics and synchronization through a secondary symmetry-breaking bifurcation

We show evidence of the frozen dynamics (Kibble-Zurek mechanism) at the transition one-dimensional (1D) front of an extended 1D array of convective oscillators that undergo a secondary subcritical bifurcation. Results correspond to a global synchronization process from nonlocal coupling between the oscillating units. The quenched dynamics exhibits defect trapping at the synchronization front according to the Kibble-Zurek mechanism, predicted for condensed matter systems. A stronger subcriticality prevents the fronts from freezing defects during the quenched transitions. A synchronization model of supercritical oscillating units is proposed to explain differentiation mechanisms in morphogenesis above a critical crossing rate when the frequency of the individual oscillators becomes coherent. The phases of such oscillators are spatially coupled through a Kuramoto-Battogtokh term that leads to the experimentally observed subcriticality. As a consequence, we show that the Kibble-Zurek mechanism overcomes non-locality of a geometrical network above a critical crossing rate

Control de la tensión del bus de continua de un filtro activo mediante un convertidor DC-DC

En este artículo se presentan los resultados experimentales obtenidos mediante un sistema compensador generador trabajando de forma aislada de la red eléctrica. Para analizar el funcionamiento del sistema se ha desarrollado un prototipo de un convertidor DC-DC bidireccional el cual permite adaptar el valor de la tensión de las baterías conectadas a su entrada con la tensión del bus de continua a la entrada del filtro activo. Para el control del convertidor DC-DC se ha utilizado un control por realimentación del estado diseñado mediante algoritmos genéticos, y en el caso del filtro activo se ha utilizado un control proporcional con prealimentación. Los resultados experimentales obtenidos muestran el correcto funcionamiento del sistema tanto en estado estacionario, como en régimen transitorio.Los autores quieren agradecer a la Universitat Jaume I y a la Generalitat Valenciana el apoyo recibido y materializado en los proyectos P11B2013-34 y GV/2014/117 respectivamente

Interaction-driven breakdown of dynamical localization in a kicked quantum gas

Quantum interference can terminate energy growth in a continually kicked system, via a single-particle ergodicity-breaking mechanism known as dynamical localization. The effect of many-body interactions on dynamically localized states, while important to a fundamental understanding of quantum decoherence, has remained unexplored despite a quarter-century of experimental studies. We report the experimental realization of a tunably-interacting kicked quantum rotor ensemble using a Bose-Einstein condensate in a pulsed optical lattice. We observe signatures of a prethermal localized plateau, followed for interacting samples by interaction-induced anomalous diffusion with an exponent near one half. Echo-type time reversal experiments establish the role of interactions in destroying reversibility. These results quantitatively elucidate the dynamical transition to many-body quantum chaos, advance our understanding of quantum anomalous diffusion, and delimit some possibilities for protecting quantum information in interacting driven systems.Comment: 17 pages including supp inf

Dynamics of secondary instability in Bénard Marangoni convection with unidimensional heating

The dynamics of Bknard-Marangoni convection with unidimensional heating in a pure fluid is studied experimentally. Convection begins with rolls parallel to the heater. The characteristics of these primary rolls have been determined. When the temperature difference across the liquid layer is increased beyond a critical value a secondary instability appears. Motions transverse to the heater with a definite wavelength can be seen. Moreover, for small angles between the heater and the fluid surface, the pattern drifts along the heater with a velocity that depends almost linearly on the inclination. A phenomenological phase equation is proposed to interpret this observation