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Despite the substantial progress made recently in understanding the role of AGN feedback and associated non-thermal effects, the precise mechanism that prevents the core of some clusters of galaxies from collapsing catastrophically by…
The excess of positrons in cosmic rays above $\sim$10 GeV has been a puzzle since it was discovered. Possible interpretations of the excess have been suggested, including acceleration in a local supernova remnant or annihilation of dark…
Cherenkov radiation (CR) generated by a charge moving through a hollow conical target made of dielectric material is analyzed. We consider two cases: the charge moves from the base of the cone to its top (``straight'' cone) or from the top…
Visible Cherenkov radiation can offers a method of the measurement of the velocity of a charged particles. The angular width of the radiation is important since it determines the resolution of the velocity measurement. In this article, the…
Vacuum Cerenkov radiation is possible in certain Lorentz-violating quantum field theories, when very energetic charges move faster than the phase speed of light. In the presence of a CPT-even, Lorentz-violating modification of the photon…
Previous work on the gravitational-wave background generated in a two-scalar-field cosmological model, in which warm inflation and the dark sector are unified within a single framework, has shown that the resulting spectrum could be…
It is shown that in some special cases the Cherenkov radiation from a charged particle moving along the axis of cylindrical waveguide filled with a semi-infinite material consisting of dielectric plates alternated with vacuum gaps is many…
A detailed analysis of vacuum Cherenkov radiation in spacelike Maxwell-Chern-Simons (MCS) theory is presented. A semiclassical treatment reproduces the leading terms of the tree-level result from quantum field theory. Moreover, certain…
Within the framework of Chern-Simons gravity, a theory that dynamically violates parity, we analyze the power spectrum of gravitational waves in light of the damping effect due to the free streaming relativistic neutrinos and dark fermions.…
We argue that if the velocity of electromagnetic waves in vacuum, \cem, is different from the limiting velocity for massive particles, \cst, then, a proton moving with velocity $\cem < v < \cst$ would radiate Cherenkov radiation. Because we…
General relativity is extended by promoting the three-dimensional gravitational Chern-Simons term to four dimensions. This entails choosing an embedding coordinate v_\mu -- an external quantity, which we fix to be a non-vanishing constant…
We calculate the gravitational wave power density emitted by quantum thermal sources. As particular cases, we calculate the emission of gravitational waves from the cosmic microwave background and from stellar sources. We study how treating…
We investigate which practical constraints are imposed by foregrounds to the detection of the B-mode polarization generated by gravitational waves in the case of experiments of the type currently being planned. Because the B-mode signal is…
We discuss the potential of future sub-10 GeV threshold imaging atmospheric Cherenkov telescope arrays for exploring the physics of rotation powered pulsars and their interactions with the ambient medium through relativistic winds and…
We propose that there may be a substantial stochastic gravitational wave background from particle origin, mainly from the gravitational three-body decay of the inflaton. The emitted gravitons could constitute a sizable contribution to dark…
Evidence of polarized $\gamma$-ray emission ($>$ 50 keV) from Gamma-Ray Bursts (GRBs) has been accumulated in recent years. Measurements have been reported with levels in the range of 30-80\%, typically with limited statistical…
We construct a consistent model of gravity where the tensor graviton mode is massive, while linearized equations for scalar and vector metric perturbations are not modified. The Friedmann equation acquires an extra dark-energy component…
We consider gravitational waves from the point of view of both their production and their propagation in doubly coupled bigravity in the metric formalism. In bigravity, the two gravitons are coupled by a non-diagonal mass matrix and show…
The radiation of relativistic charged particles for the quasiperiodic motion in a transparent medium is considered. For motion of the general kind the differential probability of the process is obtained. For planar motion the spectral…
As is well known, the gravitational degrees of freedom contained in $R+\zeta R^{2}$ (super)gravity lead to Starobinsky's potential, in a one-field setting for inflationary Cosmology that appears favored by Planck data. In this letter we…