Browsing by Author "Cuadra, Jorge"

Now showing 1 - 20 of 41
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    3D simulations of clump formation in stellar wind collisions
    (2019) Calderón Espinoza, Diego Nicolás; Cuadra, Jorge; Schartmann, Marc; Burkert, Andreas; Prieto Brito, Joaquín; Russell, Christopher M. P.
    The inner parsec of our Galaxy contains tens of Wolf-Rayet stars whose powerful outflows are constantly interacting while filling the region with hot, diffuse plasma. Theoretical models have shown that, in some cases, the collision of stellar winds can generate cold, dense material in the form of clumps. However, their formation process and properties are not well understood yet. In this work we present, for the first time, a statistical study of the clump formation process in unstable wind collisions. We study systems with dense outflows (∼10−5 M yr−1 ), wind speeds of 500–1500 km s−1, and stellar separations of ∼20–200 au. We develop 3D high resolution hydrodynamical simulations of stellar wind collisions with the adaptive-mesh refinement grid-based code RAMSES. We aim to characterise the initial properties of clumps that form through hydrodynamic instabilities, mostly via the non-linear thin shell instability (NTSI). Our results confirm that more massive clumps are formed in systems whose winds are close to the transition between the radiative and adiabatic regimes. Increasing either the wind speed or the degree of asymmetry increases the dispersion of the clump mass and ejection speed distributions. Nevertheless, the most massive clumps are very light (∼10−3–10−2 M⊕), about three orders of magnitude less massive than theoretical upper limits. Applying these results to the Galactic Centre we find that clumps formed through the NTSI should not be heavy enough either to affect the thermodynamic state of the region or to survive for long enough to fall onto the central super-massive black hole.
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    90 Winds, Some X-rays, and Sgr A* Walk Into VR...
    (2021) Russell, C. T.; Luco Korn, José Baltasar; Sepúlveda, Miguel; Cuadra, Jorge; Calderón Espinoza, Diego Nicolás; Wang, Q. Daniel
    Virtual reality (VR) provides a new tool for exploring astrophysical simulations. Our case study is hydrodynamic simulations of the central parsec of the Galactic center, which models 25 Wolf-Rayet (WR) stars that are orbiting Sgr A* while ejecting their stellar winds. The VR program we are developing allows users to fully immerse themselves in a simulation snapshot, allowing them full control over their position and viewing orientation. The highlight result so far is exquisite views of material inspiraling towards the black hole. We also present a new hydrodynamic simulation that adds 65 O and 'S' stars, which causes a reduction in thermal X-ray emission in the vicinity of Sgr A* compared to the WR-only simulations....
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    A massive binary system can feed Sgr A*
    (2017) Calderón Espinoza, Diego Nicolás; Cuadra, Jorge
    The enigmatic G2 cloud just passed pericentre around the Galactic Centre super-massive black hole, Sgr A. Despite all theoretical and observational efforts, its nature remains unclear. If purely gaseous, it is possible to explain it as a gas clump formed in a colliding wind binary. Here we study the hypothesis of G2 being one of such clumps ejected from the massive binary IRS 16SW....
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    A precessing and nutating jet in OJ287
    (2020) Britzen, S.; Fendt, C.; Witzel, G.; Qian S., J.; Pashchenko, I. N.; Kurtanidze, O.; Zajacek, M.; Martinez, G.; Karas, V.; Cuadra, Jorge; Aller, M.; Aller, H.; Eckart, A.; Nilsson, K.; Arévalo, P.; Subroweit, M.; Witzel, A.
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    Accretion of clumpy cold gas onto massive black hole binaries: a possible fast route to binary coalescence
    (2018) Garrido Goicovic, Felipe; Maureira-Fredes, Cristian; Sesana, Alberto; Amaro-Seoane, Pau; Cuadra, Jorge
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    Binary-induced spiral arms inside the disc cavity of AB Aurigae
    (2020) Poblete, Pedro P.; Calcino, Josh; Cuello, Nicolas; Macias, Enrique; Ribas, Alvaro; Price, Daniel J.; Cuadra, Jorge; Pinte, Christophe
    In this work we demonstrate that the inner spiral structure observed in AB Aurigae can be created by a binary star orbiting inside the dust cavity. We find that a companion with a mass-ratio of 0.25, semimajor axis of 40 au, eccentricity of 0.5, and inclination of 90 degrees produces gaseous spirals closely matching the ones observed in (CO)-C-12 (2-1) line emission. Based on dust dynamics in circumbinary discs (Poblete, Cuello & Cuadra 2019), we constrain the inclination of the binary with respect to the circumbinary disc to range between 60 degrees and 90 degrees. We predict that the stellar companion is located roughly 0.18 arcsec from the central star towards the east-southeast, above the plane of the disc. Should this companion be detected in the near future, our model indicates that it should be moving away from the primary star at a rate of 6 mas yr(-1) on the plane of the sky. Since our companion is inclined, we also predict that the spiral structure will appear to change with time, and not simply corotate with the companion.
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    Black Hole Binary Mergers Within Gas Discs
    (2010) Cuadra, Jorge
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    Clump formation through colliding stellar winds in the Galactic Centre
    (2017) Calderón Espinoza, Diego Nicolás; Ballone, A.; Cuadra, Jorge; Schartmann, Marc; Burkert, A.; Gillessen, S.
    We study the process of clump formation from hydrodynamic instabilities in stellar wind collisions, using analytical and numerical techniques. We show that the cloud G2 in the Galactic Centre could have been formed in this way, with the most promising sources being compact massive binaries, such as IRS 16SW....
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    Clumpy stellar winds and the obscuration of active galactic nuclei
    (2007) Nayakshin, S.; Cuadra, Jorge
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    Co-evolution of binary systems surrounded by accretion discs
    (2022) Fontecilla Suárez, Camilo José; Petrovich Balbontín, Cristóbal; Cuadra, Jorge; Pontificia Universidad Católica de Chile. Instituto de Astrofísica
    La interacción entre los sistemas binarios y sus discos de acreción se da tanto en escenarios de estrellas múltiples como en la fusión de galaxias, donde se forman sistemas binarios de agujeros negros supermasivos. En una fusión de galaxias, el gas en el remanente puede ayudar al sistema binario a perder energía por medio de fricción dinámica, y así reducir su separación hasta que la emisión de ondas gravitacionales domine, lo que lo llevará a la coalescencia. Por otro lado, en la evolución estelar, los discos de acreción son la cuna donde se formarán planetas, y la coevolución del sistema puede modificar el resultado. En este trabajo estudiamos ambos escenarios y nos enfocamos en diferentes aspectos de cada uno a través de dos publicaciones y un proyecto. En la primera publicación estudiamos la evolución a largo plazo de un SMBHB rodeado por su disco de acreción. Desarrollamos modelos 1D resolviendo las ecuaciones para la evolución de la densidad y la temperatura, y la migración del agujero negro secundario de manera autoconsistente. Con el fin de restringir la masa en el disco interno cuando la emisión de ondas gravitacionales comenza a ser relevante. En la segunda publicación, usamos el código SPH PHANTOM para modelar la etapa final de un SMBHB y exploramos cómo el disco de acreción que rodea al agujero negro principal se ve afectado por la migración debido a la emisión de ondas gravitacionales. En nuestros resultados preliminares del proyecto, extendimos PHANTOM para modelar un sistema binario de estrellas con y sin disco circumbinario para estudiar cómo su presencia puede afectar la evolución de la binaria y la morfología de los discos individuales.
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    Dust trapping around Lagrangian points in protoplanetary disks
    (2020) Montesinos, Matias; Garrido-Deutelmoser, Juan; Olofsson, Johan; Giuppone, Cristian A.; Cuadra, Jorge; Bayo, Amelia; Sucerquia, Mario; Cuello, Nicolas
    Aims. Trojans are defined as objects that share the orbit of a planet at the stable Lagrangian points L-4 and L-5. In the Solar System, these bodies show a broad size distribution ranging from micrometer (mu m) to centimeter (cm) particles (Trojan dust) and up to kilometer (km) rocks (Trojan asteroids). It has also been theorized that earth-like Trojans may be formed in extra-solar systems. The Trojan formation mechanism is still under debate, especially theories involving the effects of dissipative forces from a viscous gaseous environment.
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    From Scattered-light to Millimeter Emission : A Comprehensive View of the Gigayear-old System of HD 202628 and its Eccentric Debris Ring
    (2019) Faramaz, V.; Krist, J.; Stapelfeldt, K.R.; Bryden, G.; Mamajek, E.E.; Matra, L.; Booth, M.; Flaherty, K.; Hales, A.S.; Cuadra, Jorge
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    Galactic center gamma-ray production by cosmic rays from stellar winds and Sgr A East
    (2022) Scherer, Andres; Cuadra, Jorge; Bauer, Franz E.
    Context. The High Energy Stereoscopic System, the Major Atmospheric Gamma-ray Imaging Cherenkov Telescope, and the Very Energetic Radiation Imaging Telescope Array System have observed diffuse gamma-ray emission strongly correlated with the central molecular zone in the Galactic center. The most accepted scenario to generate this emission is via a hadronic interaction between cosmic rays (CRs) and ambient gas, where CRs are accelerated from a central and continuous source of 1 PeV protons. Aims. We explore the influence of the three-dimensional (3D) shape of the central molecular zone on the indirect observation of the CR energy density via gamma-ray detection. Methods. We simulated synthetic gamma-ray maps using a CR diffusion model with spherical injection, one isotropic diffusion coefficient, no advection, and mono-energetic particles of 1 PeV. Also, we used two different 3D gas distributions considering the observed gas column density, both with and without an inner cavity. Results. We find that when using a persistent CR source, a disk-like gas distribution is needed to reproduce the existing CR indirect observations. This is in agreement with the continuous gas distribution implied by some dynamical models and studies based on the comparison of emission and absorption molecular lines. However, it contradicts several models of the central molecular zone, which imply that this structure has a significant inner cavity. This tension can be reconciled by an additional, impulsive CR injection. Conclusions. If the central molecular zone has a cavity, a composite CR population, coming from the stellar winds of the Wolf-Rayet stars in the central 0.5 pc and the supernova Sgr A East, produces a good match to the observed gamma-ray morphology in the Galactic center.
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    How Jupiters Save or Destroy Inner Neptunes around Evolved Stars
    (2020) Paula Ronco, Maria; Schreiber, Matthias R.; Giuppone, Cristian A.; Veras, Dimitri; Cuadra, Jorge; Guilera, Octavio M.
    In about 6 Gyr our Sun will evolve into a red giant and finally end its life as a white dwarf. This stellar metamorphosis will occur to virtually all known host stars of exoplanetary systems and is therefore crucial for their final fate. It is clear that the innermost planets will be engulfed and evaporated during the giant phase and that planets located farther out will survive. However, the destiny of planets in-between, at similar to 1 and 10 au, has not yet been investigated with a multiplanet tidal treatment. We here combine for the first time multiplanet interactions, stellar evolution, and tidal effects in anN-body code to study the evolution of a Neptune-Jupiter planetary system. We report that the fate of the Neptune-mass planet, located closer to the star than the Jupiter-mass planet, can be very different from the fate of a single Neptune. The simultaneous effects of gravitational interactions, mass loss, and tides can drive the planetary system toward mean motion resonances. Crossing these resonances affects particularly the eccentricity of the Neptune and thereby also its fate, which can be engulfment, collision with the Jupiter-mass planet, ejection from the system, or survival at a larger separation.