A5076885888- Gamma-ray bursts and supernovae
- Astrophysical Phenomena and Observations
- Pulsars and Gravitational Waves Research
- Magnetic confinement fusion research
- Astrophysics and Cosmic Phenomena
- Solar and Space Plasma Dynamics
- Ionosphere and magnetosphere dynamics
- Astrophysics and Star Formation Studies
- Neutrino Physics Research
- Astro and Planetary Science
- Computational Fluid Dynamics and Aerodynamics
- Geomagnetism and Paleomagnetism Studies
- Gas Dynamics and Kinetic Theory
- Stellar, planetary, and galactic studies
- High-pressure geophysics and materials
- Parallel Computing and Optimization Techniques
- Fluid Dynamics and Turbulent Flows
- Particle physics theoretical and experimental studies
- Advanced Data Storage Technologies
- Meteorological Phenomena and Simulations
- Superconducting Materials and Applications
- Particle Accelerators and Free-Electron Lasers
- Dark Matter and Cosmic Phenomena
- Geophysical and Geoelectrical Methods
- Radio Astronomy Observations and Technology
University of Turin
2023-2024
Istituto Nazionale di Fisica Nucleare, Sezione di Torino
2024
Université Paris-Saclay
2022-2024
Université Paris Cité
2019-2024
Centre National de la Recherche Scientifique
2019-2024
CEA Paris-Saclay
2018-2024
Commissariat à l'Énergie Atomique et aux Énergies Alternatives
2019-2024
Astrophysique, Instrumentation et Modélisation
2019-2024
Institut de Recherche sur les Lois Fondamentales de l'Univers
2019-2023
CEA Paris-Saclay - Etablissement de Saclay
2018-2023
Abstract Recent developments in compact object astrophysics, especially the discovery of merging neutron stars by LIGO, imaging black hole M87 Event Horizon Telescope, and high- precision astrometry Galactic Center at close to event horizon scale GRAVITY experiment motivate development numerical source models that solve equations general relativistic magnetohydrodynamics (GRMHD). Here we compare GRMHD solutions for evolution a magnetized accretion flow where turbulence is promoted...
Fast reconnection operating in magnetically dominated plasmas is often invoked models for magnetar giant flares, magnetic dissipation pulsar winds, or to explain the gamma-ray flares observed Crab nebula; hence, its investigation of paramount importance high-energy astrophysics. Here we study, by means two-dimensional numerical simulations, linear phase and subsequent non-linear evolution tearing instability within framework relativistic resistive magnetohydrodynamics (MHD), as appropriate...
Magnetic fields can play a major role in the dynamics of outstanding explosions associated to violent events such as GRBs and hypernovae, since they provide natural mechanism harness rotational energy central proto-neutron star power relativistic jets through stellar progenitor. As structure is quite uncertain, most numerical models MHD-driven core-collapse supernovae consider an aligned dipole initial magnetic field, while field's morphology actually be much more complex. We present...
The gravitational collapse of rapidly rotating massive stars can lead to the onset low $T/\|W\|$ instability within central proto-neutron star (PNS), which leaves strong signatures in both wave (GW) and neutrino emission. Strong large-scale magnetic fields are usually invoked explain outstanding stellar explosions progenitors, but their impact on growth such has not yet been cleared. We analyze a series three-dimensional magnetohydrodynamic models characterize effects different...
The magnetic field is believed to play an important role in at least some core-collapse supernovae if its magnitude reaches $10^{15}\,\rm{G}$, which a typical value for magnetar. In the presence of fast rotation, such strong can drive powerful jet-like explosions it has large-scale coherence dipole. topology is, however, probably much more complex with multipolar and small-scale components consequences explosion are so far unclear. We investigate effects on dynamics properties forming...
Magnetars are highly magnetized neutron stars whose magnetic dipole ranges from $10^{14}$ to $10^{15}$ G. The MRI is considered be a promising mechanism amplify the field in fast-rotating protoneutron and form magnetars. This scenario supported by many local studies showing that fields could amplified on small scales. However, efficiency of at generating still unknown. To answer this question, we study dynamo an idealized global model fast rotating star with differential rotation. We perform...
Magnetars are highly magnetized neutron stars that can produce X-ray and soft gamma-ray emissions have a dipole of $10^{14}$ G to $10^{15}$ G. A promising mechanism for explaining magnetar formation is magnetic field amplification by the MRI in fast-rotating protoneutron (PNS). This scenario supported recent global models, which showed small-scale turbulence generate with magnetar-like intensity. However, impact buoyancy density stratification on efficiency generating still unknown. We...
In recent years, numerical simulations have become indispensable for addressing complex astrophysical problems. The MagnetoHydroDynamics (MHD) framework represents a key tool investigating the dynamical evolution of plasmas, which are described as set partial differential equations that enforce conservation mass, momentum, and energy, along with Maxwell's equation electromagnetic fields. Due to high nonlinearity MHD (regardless their specifications, e.g., classical/relativistic or...
Geometrically thick tori with constant specific angular momentum have been widely used in the last decades to construct numerical models of accretion flows on black holes. Such discs are prone a global non-axisymmetric hydrodynamic instability, known as Papaloizou–Pringle instability (PPI), which can redistribute and also lead an emission gravitational waves. It is, however, not clear yet how development PPI is affected by presence magnetic field concurrent magnetorotational (MRI). We...
Turbulent magnetic diffusivity plays an important role for accretion disks and the launching of disk winds. We have implemented diffusivity, respective resistivity in general relativistic MHD code HARM. This paper describes theoretical background our implementation, its numerical realization, tests preliminary applications. The test simulations new rHARM are compared with analytic solution diffusion equation a classical shock tube problem. further investigated evolution magneto-rotational...
The dynamo driven by the magnetorotational instability (MRI) is believed to play an important role in dynamics of accretion discs and may also explain origin extreme magnetic fields present magnetars. Its saturation level open question known be particularly sensitive diffusive processes through Prandtl number Pm (the ratio viscosity resistivity). Despite its relevance proto-neutron stars neutron star merger remnants, numerically challenging regime high still largely unknown. Using zero-net...
The numerical study of relativistic magnetohydrodynamics (MHD) plays a crucial role in high-energy astrophysics but unfortunately is computationally demanding, given the complex physics involved (high Lorentz factor flows, extreme magnetization, and curved spacetimes near compact objects) large variety spatial scales needed to resolve turbulent motions. A great benefit comes from porting existing codes running on standard processors GPU-based platforms. However, this usually requires drastic...
Abstract We present the first kinematic study of an αΩ-dynamo in general relativistic magnetohydrodynamics regime, applied to thick discs orbiting around Kerr black holes and using a fully covariant mean-field dynamo closure for Ohm law. show that mechanism leads continuous exponential growth magnetic field within disc formation waves drifting away or towards equatorial plane. Since evolution occurs qualitatively same fashion as Sun, we also butterfly diagrams characterize our models...
Aims. The main goal of the present paper is to provide first systematic numerical study propagation astrophysical relativistic jets, in context high-resolution shock-capturing resistive magnetohydrodynamics (RRMHD) simulations. We aim at investigating different values and models for plasma resistivity coefficient, assessing their impact on level turbulence, formation current sheets reconnection plasmoids, electromagnetic energy content, dissipated power. Methods. use PLUTO code simulations...
Abstract Core-collapse supernovae (CCSNe) offer extremely valuable insights into the dynamics of galaxies. Neutrino time profiles from CCSNe, in particular, could reveal unique details about collapsing stars and particle behavior dense environments. However, CCSNe our galaxy Large Magellanic Cloud are rare only one supernova neutrino observation has been made so far. To maximize information obtained next Galactic CCSN, it is essential to combine analyses multiple experiments real transmit...
The production of heavy elements is one the main by-products explosive end massive stars. A long sought goal finding differentiated patterns in nucleosynthesis yields, which could permit identifying a number properties core. Among them, traces magnetic field topology are particularly important for \emph{extreme} supernova explosions, most likely hosted by magnetorotational effects. We investigate five state-of-the-art magnetohydrodynamic models with fast rotation that have been previously...
Abstract The recent imaging of the M87 black hole at millimeter wavelengths by Event Horizon Telescope (EHT) collaboration has triggered a renewed interest in numerical models for accretion magnetized plasma regime general relativistic magnetohydrodynamics (GRMHD). Here non-ideal simulations, including both resistive effects and, above all, mean-field dynamo action due to sub-scale, unresolved turbulence, are applied first time such systems fully nonlinear regime. Combined with differential...
We present a novel implementation of genuinely $4^{\rm th}$-order accurate finite volume scheme for multidimensional classical and special relativistic magnetohydrodynamics (MHD) based on the constrained transport (CT) formalism. The introduces several aspects when compared to its predecessors yielding more efficient computational tool. Among most relevant ones, our exploits pointwise reconstructions (rather than one-dimensional ones), employs generic upwind averaging sophisticated limiting...
Large-scale, ordered magnetic fields in several astrophysical sources are supposed to be originated, and maintained against dissipation, by the combined amplifying action of rotation small-scale turbulence. For instance, solar interior, so-called α−Ω mean-field dynamo is known responsible for observed 22-years cycle. Similar mechanisms could operate more extreme environments, like proto neutron stars accretion disks around black holes, which physical modelling needs translated from regime...
ABSTRACT We present a finite-volume, genuinely fourth-order accurate numerical method for solving the equations of resistive relativistic magnetohydrodynamics in Cartesian coordinates. In our formulation, magnetic field is evolved time terms face-average values via constrained-transport method, while remaining variables (density, momentum, energy, and electric fields) are advanced as cell volume averages. Spatial accuracy employs fifth-order WENO-Z reconstruction from point (as described...
We present here a kinematic study of dynamo effects in thick accretion disks using the most recent version ECHO code. This allowed us to perform high-order simulations resistive plasma within 3 + 1 GRMHD frame with fully covariant mean-field closure for Ohm's law. The magnetic field goes through an exponential growth few orbital periods disk, and we derive butterfly diagrams qualitatively same fashion as Sun. Finally, typical time-scale evolution is found, that depends on resistivity...
The remarkable results by the Event Horizon Telescope collaboration concerning emission from M87* and, more recently, its polarization properties, require an increasingly accurate modeling of plasma flows around accreting black hole. Radiatively inefficient sources such as and Sgr A* are typically modeled with SANE (standard normal evolution) paradigm, if accretion dynamics is smooth, or MAD (magnetically arrested disk) hole’s magnetosphere reacts halting sporadically, resulting in a highly...