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Scientists link star-shredding event to origins of universe's highest-energy particles（图）
Scientists star-shredding event origins universe highest-energy particles
2021/3/5
A team of scientists has detected the presence of a high-energy neutrino -- a particularly elusive particle -- in the wake of a star's destruction as it is consumed by a black hole.The discovery is a ...
Three Types Of Extreme-Energy Space Particles May Have Unified Origin（图）
Three Types Extreme-Energy Space Particles Unified Origin
2018/2/1
One of the biggest mysteries in astroparticle physics has been the origins of ultrahigh-energy cosmic rays, very high-energy neutrinos, and high-energy gamma rays. Now, a new theoretical model reveals...
The interstellar medium is not necessary fully ionized. When a shock propagates into the partially ionized medium, some neutral particles leak into the upstream region from the downstream region. In t...
On ghosts in theories of self-interacting massive spin-2 particles
ghosts theories self-interacting massive spin-2 particles
2011/10/17
We consider general theories of a massive spin-2 particle $h_{\mu\nu}$ on a Minkowski background. A decomposition of $h_{\mu\nu}$ in terms of helicity eigenstates allows us to directly test whether an...
Magnetic Fields, Relativistic Particles, and Shock Waves in Cluster Outskirts
Magnetic Fields Relativistic Particles Shock Waves Cluster Outskirts
2011/10/20
It is only now, with low-frequency radio telescopes, long exposures with high-resolution X-ray satellites and gamma-ray telescopes, that we are beginning to learn about the physics in the periphery of...
Acceleration of particles by rotating black holes: near-horizon geometry and kinematics
Acceleration particles rotating black holes: near-horizon geometry kinematics
2011/10/14
Nowadays, the effect of infinite energy in the centre of mass frame due to near-horizon collisions attracts much attention.We show generality of the effect combining two seemingly completely different...
Excitation of the aromatic infrared emission bands: Chemical energy in hydrogenated amorphous carbon particles?
Excitation aromatic infrared emission bands: Chemical energy
2011/10/11
We outline a model for the heating of hydrogenated amorphous (HAC) dust via the release of stored chemical energy and show that this energy (~12 kJ/mole) is sufficient to heat dust grains of classical...
Can axion-like particles explain the alignments of the polarisations of light from quasars?
axion-like particles explain alignments polarisations
2011/9/30
The standard axion-like particle explanation of the observed large-scale coherent orientations of quasar polarisation vectors is ruled out by the recent measurements of vanishing of circular polarisat...
Acceleration of particles by black holes -- general explanation
Acceleration black holes general explanation
2010/11/16
We give simple and general explanation to the effect of unbound acceleration of particles by black holes. It is related to the fact that the scalar product of a timelike vector of the four-velocity of...
GEANT4 Simulations of Gamma-Ray Emission from Accelerated Particles in Solar Flares
Solar and Stellar Astrophysics (astro-ph.SR)
2010/12/28
Gamma-ray spectroscopy provides diagnostics of particle acceleration in solar flares, but care must be taken when interpreting the spectra due to effects of the angular distribution of the accelerated...
Residence Times of Particles in Diffusive Protoplanetary Disk Environments I. Vertical Motions
Earth and Planetary Astrophysics (astro-ph.EP)
2010/12/27
The chemical and physical evolution of primitive materials in protoplanetary disks are determined by the types of environments they are exposed to and their residence times within each environment.
The Relation Between Charged Particles and Muons With Threshold Energy 1 GeV in Extensive Air Showers Registered at the Yakutsk EAS Array
High Energy Astrophysical Phenomena (astro-ph.HE)
2010/12/24
Characteristics of the muon component in EAS are analyzed together with their fluctuations. The aim of this analysis -- a comparison of experimental data with computational results obtained within fra...
Domain Wall, Stiff Matter and Ultra-Relativistic Particles from a Generalized Double-Component Dark Energy Model
Super-accelerated expansion dark energy domain wall cosmic string stiff matter
2010/6/30
This letter discusses a modified Friedmann-Robertson-Walker cosmology in which the equation of state behaves like p = 3hamrn r; (h;m;n) 2 R. Many interesting features are revealed in particu...
On saturation of betatron acceleration of dust particles behind shock fronts
betatron acceleration dust particles shock fronts
2010/3/9
Possible saturation of betatron acceleration of dust particles behind strong shock fronts from supernovae is considered. It is argued that the efficiency of the nonthermal dust destruction should be s...
Luke-warm dark matter: Bose-condensation of ultra-light particles
Luke-warm dark matter ultra-light particles
2010/3/18
We discuss the thermal evolution and Bose condensation of ultra-light scalar particles with Compton wavelength of galactic scales. We find an upper bound of 1.5 K for the dark matter temperature from ...