Related papers: Ordinary Stars as Potential TeV Cosmic-Ray Acceler…
Cosmic-ray electrons and positrons (CREs) at GeV-TeV energies are a unique probe of our local Galactic neighbourhood. CREs lose energy rapidly via inverse Compton scattering and synchrotron processes while propagating in the Galaxy,…
Suppose that even the highest energy cosmic rays (CRs) observed on Earth are protons accelerated in local Milky Way Galaxy sources, with few if any from more distant sources. In this paper we treat the problem that supernovae remnants…
The origin of Galactic cosmic rays (CR) is still a matter of debate. Diffusive shock acceleration (DSA) applied to supernova remnant (SNR) shocks provides the most reliable explanation. However, within the current understanding of DSA…
It has been shown that supernova blast waves interacting with winds from massive stars in compact star clusters may be capable of producing cosmic-ray (CR) protons to above $10^{17}$ eV. We give a brief description of the…
Galactic cosmic rays are believed to be accelerated at supernova remnants. However, whether supernova remnants can be Pevatrons is still very unclear. In this work we argue that PeV cosmic rays can be accelerated during the early phase of a…
We explore two generic hypotheses for tracing the sources of ultra-high energy cosmic rays (UHECRs) in the Universe: star formation rate density or stellar mass density. For each scenario, we infer a set of constraints for the emission…
A significant fraction of the energy density of the interstellar medium is in the form of high-energy charged particles (cosmic rays). The origin of these particles remains uncertain. Although it is generally accepted that the only sources…
In the standard Galactic cosmic-ray (CR) paradigm, protons are accelerated up to ~1 PeV by Galactic sources. While supernova remnants (SNRs) have been traditionally considered as the primary accelerators, recent observations by LHAASO and…
The most powerful persistent accelerators in the Universe are jetted active galaxies. Blazars, galaxies whose jets are directed towards Earth, dominate the extragalactic gamma-ray sky. Still, most of the highest-energy particle accelerators…
The Cygnus Cocoon is the first gamma-ray superbubble powered by a massive stellar association, the OB2 association. It was postulated that the combined effects of the stellar winds of all the massive O-type stars of the OB2 association can…
The high-energy radiation from short period binaries containing a massive star with a compact relativistic companion was detected from radio to TeV gamma rays. We show here that PeV regime protons can be efficiently accelerated in the…
Context. Star clusters are often invoked as contributors to the flux of Galactic cosmic rays and as sources potentially able to accelerate particles to $\sim$PeV energies. The gamma radiation with $E\gtrsim$ TeV recently observed from…
In this review we discuss the important progress made in recent years towards understanding the experimental data on cosmic rays with energies $\agt 10^{19}$ eV. We begin with a brief survey of the available data, including a description of…
The multi-TeV $\gamma$-rays from the Galactic Center (GC) have a cutoff at tens of TeV, whereas the diffuse emission has no such cutoff, which is regarded as an indication of PeV proton acceleration by the HESS experiment. It is important…
The hunt for cosmic TeV particle accelerators is prospering through Imaging Atmospheric Cerenkov Telescopes. We face challenges such as low light levels and MHz trigger rates, and the need to distinguish between particle air showers…
We derive constraints that must be satisfied by the sources of ~10^{15} to ~10^{18} eV cosmic rays, under the assumption that the sources are Galactic. We show that while these constraints are not satisfied by ordinary supernovae (SNe),…
The origin of Galactic CRs up the knee energy remains unanswered and provides strong motivation for the study of gamma-ray sources at energies above 10 TeV. We discuss recent results from ground-based gamma-ray Cherenkov imaging systems at…
The term PeVatron designates astrophysical objects capable of accelerating particles to PeV energies. Their nature and particle acceleration mechanisms are uncertain, but ultra-high-energy gamma rays are produced when particles accelerated…
In 1990's Very High Energy Gamma-ray Astrophysics has dramatically advanced due to the Imaging Air \v{C}erenkov Telescopes(IACTs). After the first detection of TeV gamma-ray emission from the Crab nebula in 1989, several type of TeV…
Supernova remnants are often presented as the most probable sources of Galactic cosmic rays. This idea is supported by the accumulation of evidence that particle acceleration is happening at supernova remnant shocks. Observations in the TeV…