Related papers: CRAFT (Cosmic Ray Acceleration From Turbulence) in…
Cosmic rays (CR) play an important role in dense molecular cores, affecting their thermal and dynamical evolution and initiating the chemistry. Several studies have shown that the formation of protostellar discs in collapsing clouds is…
Diffuse interstellar clouds show large abundances of H_3^+ which can be maintained only by a high ionization rate of H_2. Cosmic rays are the dominant ionization mechanism in this environment, so the large ionization rate implies a high…
The theory of cosmic-ray (CR) penetration into dense molecular clouds developed recently for relativistic particles by Chernyshov et al. (2024) is extended to non-relativistic CRs. Interstellar CRs streaming into the clouds are able to…
We analyze the processes governing cosmic-ray (CR) penetration into molecular clouds and the resulting generation of gamma-ray emission. The density of CRs inside a cloud is depleted at lower energies due to the self-excited MHD turbulence.…
Cosmic rays (CRs) can significantly impact dense molecular clouds in galaxies, heating the interstellar medium (ISM) and altering its chemistry, ionization, and thermal properties. Their influence is particularly relevant in environments…
We investigate how cosmic ray (CR) transport in molecular clouds and their substructures can be probed using multi-wavelength observations. The detailed microphysics regulating the penetration and coupling of CRs in dense molecular…
Particle acceleration in the inner ~ 200 pc of the Galaxy is discussed, where diffuse TeV gamma-rays have been detected by the High Energy Stereoscopic System (HESS) observation. The diffuse gamma-ray emission has a strong correlation with…
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…
This paper deals with the cosmic-ray penetration into molecular clouds and with the related gamma--ray emission. High energy cosmic rays interact with the dense gas and produce neutral pions which in turn decay into two gamma rays. This…
Although the origin of cosmic rays (CRs) remains an open question, collisionless magnetized shock waves are widely regarded as key sites for particle acceleration. Recent theories further suggest that shock-shock collisions in stellar…
The bulk propagation speed of GeV-energy cosmic rays is limited by frequent scattering off hydromagnetic waves. Most galaxy evolution simulations that account for this confinement assume the gas is fully ionized and cosmic rays are…
Low-energy cosmic rays ($E\lesssim 1$ GeV) are responsible for the ionisation and heating of molecular clouds. While the role of supra-thermal electrons produced in the ionisation process in inducing excitation of the ambient gas (mostly…
We have calculated the cosmic ray (CR) acceleration at young remnants from Type Ia supernovae expanding into a uniform interstellar medium (ISM). Adopting quasi-parallel magnetic fields, gasdynamic equations and the diffusion convection…
Subsonic, compressive turbulence transfers energy to cosmic rays (CRs), a process known as non-resonant reacceleration. It is often invoked to explain observed ratios of primary to secondary CRs at $\sim \rm GeV$ energies, assuming wholly…
Acceleration of cosmic-ray electrons (CRe) in the intra-cluster-medium (ICM) is probed by radio observations that detect diffuse, Mpc-scale, synchrotron sources in a fraction of galaxy clusters. Giant radio halos are the most spectacular…
A scenario in which cosmic rays (CRs) above $10^{20}{\rm eV}$ are produced by cosmological gamma-ray bursts (GRBs) is consistent with observations provided that deflections by the inter-galactic magnetic field (IGMF) delay and spread the…
The galactic diffuse $\gamma$-ray emission, as seen by Fermi Large Area Telescope (LAT), shows a sharp peak in the region around 4 kpc from the Galactic center, which can be interpreted either as due to an enhanced density of cosmic-ray…
In recent years, exciting developments have taken place in the identification of the role of cosmic rays in star-forming environments. Observations from radio to infrared wavelengths and theoretical modelling have shown that low-energy…
The nature of cosmic rays (CRs) and cosmic ray transport in galaxy clusters is probed by a number of observations. Radio observations reveal the synchrotron radiation of cosmic ray electrons (CRe) spiraling around cluster magnetic fields.…
Starburst galaxies are efficient $\gamma$-ray producers, because their high supernova rates generate copious cosmic ray (CR) protons, and their high gas densities act as thick targets off which these protons can produce neutral pions and…