Results 21 to 30 of about 20,645 (111)

Long‐Range Scalar Forces in Five‐Dimensional General Relativity

Advances in Mathematical Physics, Volume 2020, Issue 1, 2020., 2020
We present new results regarding the long‐range scalar field that emerges from the classical Kaluza unification of general relativity and electromagnetism. The Kaluza framework reproduces known physics exactly when the scalar field goes to one, so we studied perturbations of the scalar field around unity, as is done for gravity in the Newtonian limit ...
L. L. Williams, Eugen Radu
wiley   +1 more source

Axion-like particles and high-energy gamma rays: interconversion revisited [PDF]

PoS(ICRC2023)1383, 2023
Axion-like particles (ALPs) are hypothetical entities often invoked to solve various problems in particle physics to cosmology. They are one of the most promising candidates to explain the elusive dark matter. A way to search for ALPs is through their effects on photons. In the presence of external magnetic fields, ALPs and photons can convert into one
arxiv   +1 more source

Antigravity, an Answer to Nature’s Phenomena including the Expansion of the Universe

Advances in High Energy Physics, Volume 2020, Issue 1, 2020., 2020
The gravitational attraction force being proportional to the mass has been experimentally shown for several hundred years now, but no gravitational repulsion has been identified within the accepted scientific reasoning. Here, we show that the gravitational repulsion force, similar to the gravitational attraction among particles has also been in ...
C. K. Gamini Piyadasa, Farook Rahaman
wiley   +1 more source

On the propagation of the highest energy cosmic ray nuclei [PDF]

JHEP 9810:009,1998, 1998
We study the propagation of ultra-high energy cosmic ray nuclei through the background of cosmic microwave and intergalactic infrared photons, using recent re-estimates for the density of the last ones. We perform a detailed Monte Carlo simulation to follow the disintegration histories of nuclei starting as Fe and reaching the Earth from extragalactic ...
arxiv   +1 more source

The Magnetic Field in Galaxies, Galaxy Clusters, and the InterGalactic Space [PDF]

Phys.Rev. D72 (2005) 123002, 2005
Magnetic fields of debated origin appear to permeate the Universe on all large scales. There is mounting evidence that supernovae produce not only roughly spherical ejecta and winds, but also highly relativistic jets of ordinary matter. These jets, which travel long distances, slow down by accelerating the matter encountered on their path to cosmic-ray
arxiv   +1 more source

IGM metal enrichment through dust sputtering [PDF]

Mon.Not.Roy.Astron.Soc. 358 (2005) 379-396, 2005
We study the motion of dust grains into the Intergalactic Medium (IGM) around redshift z=3, to test the hypothesis that grains can efficiently pollute the gas with metals through sputtering. We use the results available in the literature for radiation-driven dust ejection from galaxies as initial conditions, and follow the motion onward.
arxiv   +1 more source

Microquasars as heating sources of the intergalactic medium during reionisation of the Universe [PDF]

, 2017
The effect of the primeval sources of radiation and particles on the thermodynamical state of the intergalactic medium during the Epoch of Reionisation is still unclear. In this work, we explore the contribution of electrons accelerated in the jets of high-redshift microquasars to heating and ionising the intergalactic medium.
arxiv   +1 more source

Ultra-High Energy Cosmic Rays and Neutron-Decay Halos from Gamma Ray Bursts [PDF]

, 2001
Simple arguments concerning power and acceleration efficiency show that ultra-high energy cosmic rays (UHECRS) with energies >~ 10^{19} eV could originate from GRBs. Neutrons formed through photo-pion production processes in GRB blast waves leave the acceleration site and travel through intergalactic space, where they decay and inject a very energetic ...
arxiv   +1 more source

The Universe is at Most 88% Neutral at z=10.6 [PDF]

, 2023
Recent observations of GN-z11 with JWST have revealed a Ly$\alpha$ emission line with an equivalent width of 18$\pm 2$ angstroms. At z=10.6, this galaxy is expected to lie in the heart of reionization. We use a series of inhomogeneous reionization simulations to derive the distribution of the Ly$\alpha$ EW after traveling through the neutral ...
arxiv   +1 more source

Axion-photon Propagation in Magnetized Universe [PDF]

, 2015
Oscillations between photons and axion-like particles (ALP) travelling in intergalactic magnetic fields have been invoked to explain a number of astrophysical phenomena, or used to constrain ALP properties using observations. One example is the anomalous transparency of the universe to TeV gamma-rays. The intergalactic magnetic field is usually modeled
arxiv   +1 more source