A5102884937- Astrophysical Phenomena and Observations
- Astrophysics and Star Formation Studies
- Astro and Planetary Science
- Stellar, planetary, and galactic studies
- Astrophysics and Cosmic Phenomena
- Pulsars and Gravitational Waves Research
- Gamma-ray bursts and supernovae
- Solar and Space Plasma Dynamics
- Mechanics and Biomechanics Studies
- Fluid Dynamics and Turbulent Flows
- Magnetic confinement fusion research
- Galaxies: Formation, Evolution, Phenomena
- Atomic and Molecular Physics
- High-pressure geophysics and materials
- Astronomical Observations and Instrumentation
- Ionosphere and magnetosphere dynamics
- Dark Matter and Cosmic Phenomena
- Astronomy and Astrophysical Research
- Cosmology and Gravitation Theories
- Molecular Spectroscopy and Structure
- SAS software applications and methods
- Black Holes and Theoretical Physics
- Scientific Measurement and Uncertainty Evaluation
- Wireless Power Transfer Systems
- Aerodynamics and Fluid Dynamics Research
Centre National de la Recherche Scientifique
2013-2024
Institut de Planétologie et d'Astrophysique de Grenoble
2012-2024
Université Grenoble Alpes
2013-2024
Analog Devices (United States)
2023
Worcester Polytechnic Institute
2023
IPAG Business School
2021
Laboratoire de Géologie de Lyon : Terre, Planètes et Environnement
2019
Université Claude Bernard Lyon 1
2019
Universidade Federal da Paraíba
2017
Biotherapy of Genetic Diseases, Inflammatory Disorders and Cancers
2017
The tidal torque exerted by a protoplanetary disk with power-law surface density and temperature profiles onto an embedded embryo is generally negative quantity that leads to the inward migration. Here we investigate how balance affected at radial jump. jump has two consequences: (1) It affects differential Lindblad torque. In particular, if merely empty on inner side, almost amounts large outer (2) corotation torque, which very sensitive local gradient of density. depleted inside occurs...
AIMS: We examine whether ejection phenomena from accreting T Tauri stars can be described by only one type of self-collimated jet model. METHODS: present analytical kinematic predictions valid soon after the Alfvén surface for all types steady magnetically self-confined jets. RESULTS: show that extended disc winds, X-winds, and stellar winds occupy distinct regions in poloidal speed vs. specific angular momentum plane. Comparisons with current observations jets yield quantitative constraints...
The planet-forming region of protoplanetary disks is cold, dense, and therefore weakly ionized. For this reason, magnetohydrodynamic (MHD) turbulence thought to be mostly absent, another mechanism has found explain gas accretion. It been proposed that magnetized winds, launched from the ionized disk surface, could drive accretion in presence a large-scale magnetic field. efficiency impact these surface winds on structure still highly uncertain. We present first global simulations exhibits...
We present a new picture for the central regions of Black Hole X-ray Binaries. In our view, these have multi-flow configuration which consists in (1) an outer standard accretion disc down to transition radius rJ; (2) inner magnetized below rJ driving (3) non relativistic self-collimated electron-proton jet surrounding, when adequate conditions pair creation are met; (4) ultra electron-positron beam. This accretion-ejection paradigm provides simple explanation canonical spectral states, from...
Molecular counterparts to atomic jets have been detected within 1000 AU of young stars. Reproducing them is a challenge for proposed ejection models. We explore whether molecules may survive in an MHD disk wind invoked reproduce the kinematics and tentative rotation signatures T Tauri The coupled ionization, chemical thermal evolution along dusty flow streamlines computed prescribed solution, using method developed magnetized shocks interstellar medium. Irradiation by wind-attenuated coronal...
Recent observations revealed organised structures in protoplanetary disks, such as axisymmetric rings or horseshoe concen- trations evocative of large-scale vortices. These are often interpreted the result planet-disc interactions. However, these disks also known to be unstable magneto-rotational instability (MRI) which is believed one dominant angular momentum transport mechanism objects. It therefore natural ask if MRI itself could produce without invoking planets. The nonlinear evolution...
Context. Astrophysical disks are likely embedded in an ambient vertical magnetic field generated by its environment. This is known to drive magneto-rotational turbulence the disk bulk, but it also responsible for launching magnetised outflows at origin of astrophysical jets. Yet, interplay between and not understood. In particular, structure long-term (secular) evolution such a system lack quantitative predictions. It is, nevertheless, this secular which proposed explain time variability...
We have produced brightness and magnetic field maps of the surfaces CV Cha CR Cha: two actively accreting G K-type T Tauri stars in Chamaeleon I star-forming cloud with ages 3-5 Myr. Our show evidence for strong, complex multi-polar fields similar to those obtained young rapidly rotating main sequence stars. Brightness indicate presence dark polar caps low latitude spots -- these are very other pre-main Only classical been studied using techniques so far: V2129 Oph BP Tau. patterns that...
We studied X-ray reverberation lags in the BHXRB GX 339-4 at end of 2014-2015 outburst. analysed data from a XMM-Newton campaign covering transition soft to hard state, and decrease luminosity state. During all observations we detected, high frequencies, significant disc variability, responding variations power law emission with an average time delay $\sim0.009\pm 0.002$ s. These new detections thermal add those previously obtained suggest lag be always present hard-intermediate states. Our...
Context. Jets are commonly detected in post-asymptotic giant branch (post-AGB) binaries and originate from an accretion process onto the companion of post-AGB primary. These jets revealed by high-resolution spectral time series. Aims. This paper is part a In this work, we move away our previous parametric modelling include self-similar wind model that allows physical properties to be characterised. describes magnetically driven thin disk threaded large-scale, near equipartition vertical...
Context.The radial structure of accretion disks is a fundamental issue regarding star and planet formation. Many theoretical studies, focussing on different aspects such as e.g. disk emissivity or ionisation, have been conducted in the context standard (SAD) model, where no jet present.
It has been suggested that the cycles of activity X-ray Binaries (XrB) are triggered by a switch in dominant disk torque responsible for accretion (paper I). As rate increases, innermost regions would change from jet-emitting (JED) to standard (SAD). While JEDs have proven successfully reproduce hard states II), existence an outer cold SAD introduces extra non local cooling term. We investigate thermal structure and associated spectra such hybrid configuration. use 2T plasma code elaborated...
We elaborate on the paradigm proposed in Ferreira et al. (2006), where increase and decrease disk accretion rate is accompanied by a modification of magnetization $\mu \propto B_z^2/\dot{m}_{in}$, which turn determines dominant torque allowing accretion. For $\mu>0.1$, flow produces jets that vertically, carry away angular momentum (jet-emitting or JED). The goal this paper to investigate spectral signatures JED configurations. have developed two-temperature plasma code computes local...
Semi-analytical models of disk outflows have successfully described magnetically-driven, self-confined super-Alfv\'enic jets from near Keplerian accretion disks. These Jet Emitting Disks are possible for high levels magnetization $\mu$ defined as $\mu=2/\beta$ where beta is the usual plasma parameter. In near-equipartition JEDs, supersonic and carry away most angular momentum. However, these solutions prove difficult to compare with cutting edge numerical simulations, reason that simulations...
Using the simultaneous Infra-Red (IR) and X-ray light curves obtained by Kalamkar et al. (2016), we perform a Fourier analysis of IR/X-ray timing correlations black hole binary (BHB) GX 339-4. The resulting IR vs coherence lag spectra are similar to those in previous studies 339-4 using optical curves. In particular, above 1 Hz, spectrum features an approximately constant about 100 ms. We model simultaneously radio Spectral Energy Distribution (SED), Power Density (PSD), jet internal shock...
Transients XrB exhibit different spectral shapes during their evolution. In luminosity-color diagrams, X-ray behavior forms unexplained q-shaped cycles. We proposed a framework where the innermost regions of accretion disk evolve as response to variations imposed in outer regions. These lead not only modifications inner rate $\dot m_{in}$ but also evolution transition radius $r_J$ between two The outermost region is standard (SAD), whereas jet-emitting (JED) all angular momentum carried away...
We test the two-corona accretion scenario for active galactic nuclei in case of `bare' Seyfert 1 galaxy HE 1143-1810. perform a detailed study broad-band UV--X-ray spectral properties and short-term variability. present results joint XMM-Newton NuSTAR monitoring source, consisting 5x20 ks observations, each separated by 2 days, performed December 2017. The source is variable flux among different correlation observed between UV X-ray emission. Moderate variability soft band. time-averaged...
Large millimeter interferometers are revealing a growing number of rotating outflows, which suggested to trace magneto-centrifugal disk winds (MHD DWs). However, their impact on accretion is not yet well quantified. Here we identify systematic biases in retrieving the true launch zone, magnetic lever arm, and angular momentum flux an MHD DW from apparent rotation signatures. Synthetic position-velocity cuts constructed self-similar DWs over broad range parameters, three different methods...
Abstract Rotating outflows from protostellar disks might trace extended magnetohydrodynamic (MHD) disk winds (DWs), providing a solution to the angular momentum problem in accretion for star formation. In jet system HH 212, rotating outflow was detected SO around an episodic SiO. Here we spatially resolve this into three components: collimated aligned with SiO jet, wide-angle outflow, and evacuated cavity between created by large jet-driven bow shock. Although it theoretically predicted, is...
Non-relativistic, magnetically-driven jets are constructed by taking self-consistently into account the feedback on underlying accretion disc. It is shown that such mostly described ejection index $ξ= \mbox{d} \ln \dot M_a/ \mbox{d}\ln r$, which a local measure of disc efficiency. This parameter found to lie in very narrow range, due global disc-jets constraints. investigation provided two important results. First, vertical equilibrium imposes minimum mass flux ejected. Second, their...
We present self-similar models of resistive viscous Keplerian disks driving nonrelativistic MHD jets and becoming super-fast-magnetosonic. show that in order to obtain such solutions, the thermal pressure must be a sizeable fraction poloidal magnetic at Alfvén surface. These steady solutions undergo recollimation shock causally disconnected from engine account for structures with high-temperature plasma sub-Alfvénic region. suggest only unsteady outflows typical timescales several disk...