Related papers: About Geometry and Initial Phase of Cloud-to-Groun…
A well-known property of linear resistive electrical networks is that the current distribution minimizes the total dissipated energy. When the circuit includes resistors with nonlinear monotonic characteristic, the current distribution…
Luminescence as a mechanism for terahertz emission from femtosecond laser-induced plasmas is studied. By using a fully microscopic theory, Coulomb scattering between electrons and ions is shown to lead to luminescence even for a spatially…
Molecular clouds are expected to emit non-thermal radiation due to cosmic ray interactions in the dense magnetized gas. Such emission is amplified if a cloud is located close to an accelerator of cosmic rays and if energetic particles can…
(Abridged) The propagation of ionizing radiation through model atmospheres of terrestrial-like exoplanets is studied for a large range of column densities and incident photon energies using a Monte Carlo code we have developed to treat…
Sandstorms are frequently accompanied by the generation of intense electric fields and lightning. In a very narrow region close to the ground level, sand particles undergo a charge exchange mechanism whereby larger (resp. smaller) sized…
We propose a mechanism for the early generation of the mean Intracluster magnetic field in terms of magnetized galactic winds. These winds are the result of starburst phases of the cluster galaxies, assumed to produce the predominant…
The little we do know of the physical conditions in gamma-ray bursters makes them conducive to the acceleration of high-energy cosmic rays, especially if they are at cosmological distances. We find that, with the observed statistics and…
Molecular clouds are expected to emit non-thermal radiation due to cosmic ray interactions in the dense magnetized gas. Such emission is amplified if a cloud is located close to an accelerator of cosmic rays and if cosmic rays can leave the…
Halos and elves are Transient Luminous Events (TLEs) produced in the lower ionosphere as a consequence of lightning-driven electromagnetic fields. These events can influence the upper-atmospheric chemistry and produce optical emissions. We…
This paper reports the discovery of evidence for physical contact between the Galactic circumnuclear disk (CND) and an exterior giant molecular cloud. The central 10 pc of our Galaxy has been imaged in the HCN J=1-0, HCO+ J=1-0, CS J=2-1,…
A self-consistent two-dimensional model is proposed to account for the transient mesospheric nighttime optical emissions associated to possible intra-cloud (IC) lightning occurring in the Venusian troposphere. The model calculates the…
Analysis of the observational data and possible origination scenarios of particle bursts allows us to conclude that the bursts can be explained by the electron acceleration in the thunderous atmosphere and by gigantic showers developed in…
Signs of lightning on Venus have long been sought, including by space missions and ground-based telescopes searching for optical flashes, plasma waves, or radio signatures. These efforts have yielded conflicting findings regarding the…
Turbulent plasma motion is common in the universe, and invoked in solar flares to drive effective acceleration leading to high energy electrons. Unresolved mass motions are frequently detected in flares from extreme ultraviolet (EUV)…
While lightning activity in Venus is still controversial, its existence in Jupiter and Saturn was first detected by the Voyager missions and later on confirmed by Cassini and New Horizons optical recordings in the case of Jupiter, and…
Cosmic rays are a fundamental source of ionization for molecular and diffuse clouds, influencing their chemical, thermal, and dynamical evolution. The amount of cosmic rays inside a cloud also determines the $\gamma$-ray flux produced by…
We report on further evidence that solar energetic particles are organized by the kinematic properties of coronal mass ejections (CMEs)[1]. In particular, we focus on the starting frequency of type II bursts, which is related to the…
Solar flares are the most powerful explosions occurring in the solar system, which may lead to disastrous space weather events and impact various aspects of our Earth. So far, it is still a big challenge in modern astrophysics to understand…
We propose that interstellar extreme scattering events, usually observed as pulsar scintillations, may be caused by a coherent agent rather than the usually assumed turbulence of $\rm H_2$ clouds. We find that the penetration of a flux of…
The angular clustering of 5 Ultrahigh Energy Cosmic Rays (UHECRs) in the combined published AGASA-HiRes data has a probability of ~ 2 10^-3 of occurring by chance. A first analysis of the implications of the event energies and angular…