Results 51 to 60 of about 19,051 (197)

Constraining axion-like particles with the diffuse gamma-ray flux measured by the Large High Altitude Air Shower Observatory

European Physical Journal C: Particles and Fields, 2022
The detection of very high-energy neutrinos by IceCube experiment supports the existence of a comparable gamma-ray counterpart from the same cosmic accelerators. Under the likely assumption that the sources of these particles are of extragalactic origin,
Leonardo Mastrototaro, Pierluca Carenza, Marco Chianese, Damiano F. G. Fiorillo, Gennaro Miele, Alessandro Mirizzi, Daniele Montanino   +6 more
doaj   +1 more source

Magnetic fields in extragalactic jets

The Astrophysical Journal, 1987
Observations indicate that jets (i.e., charged particle beams) are emitted from the central black hole sources of active galactic nuclei and quasars. Magnetic fields are produced in e(-)-p or e(-)-e(+)-p jets when electrons (and positrons) are slowed with respect to protons in the jets. Interaction with an ambient interstellar gas or external radiation
openaire   +1 more source

Reduced Geomagnetic Shielding During the Laschamps Excursion and Its Impact on Cosmic‐Ray‐Induced Atmospheric Radiation

Journal of Geophysical Research: Space Physics, Volume 131, Issue 2, February 2026.
Abstract The Laschamps geomagnetic excursion (≈41,000 years BP) was a period of significant weakening and incomplete reversal of the Earth's magnetic field. The weakening substantially reduced geomagnetic shielding against cosmic rays (CRs), which contribute to phenomena at Earth, such as cosmogenic isotope production, and atmospheric ionisation and ...
N. Larsen, I. Usoskin, A. Mishev, S. Koldobskiy, P. Väisänen   +4 more
wiley   +1 more source

Simulations of extragalactic magnetic fields and of their observables [PDF]

Classical and Quantum Gravity, 2017
The origin of extragalactic magnetic fields is still poorly understood. Based on a dedicated suite of cosmological magneto-hydrodynamical simulations with the ENZO code we have performed a survey of different models that may have caused present-day magnetic fields in galaxies and galaxy clusters. The outcomes of these models differ in cluster outskirts,
Vazza, F., BrÃ1⁄4ggen, M., Gheller, C., Hackstein, S., Wittor, D., Hinz, P. M.   +5 more
openaire   +4 more sources

The Stochastic‐Dissipative Störmer Problem‐Trajectories and Radiation Patterns

Annalen der Physik, Volume 537, Issue 12, December 2025.
We consider charged particle motion and radiation in a dipole magnetic field, in the presence of friction and of stochastic forces. The numerical solutions of the Langevin equation reveal how these forces modify the complex dynamics of particles, and they offer some new insights into the nonlinear processes relevant to planetary radiation belts ...
Tiberiu Harko, Gabriela Raluca Mocanu
wiley   +1 more source

Constraining the Astrophysical Origin of Intergalactic Magnetic Fields

The Astrophysical Journal
High-energy photons can produce electron–positron pairs upon interacting with the extragalactic background light. These pairs will in turn be deflected by the intergalactic magnetic field (IGMF), before possibly up-scattering photons of the cosmic ...
J. Tjemsland, M. Meyer, F. Vazza
doaj   +1 more source

Propagation of high-energy cosmic rays in extragalactic turbulent magnetic fields: resulting energy spectrum and composition

, 2007
We extend previous studies of mixed-composition extragalactic cosmic-ray source models, by investigating the influence of a non-negligible extragalactic magnetic field on the propagated cosmic-ray spectrum and composition.
Allard, Allard, Allard, Aloisio, Ave, Berezinsky, Bird, Blasi, Bunker, Casse, D. Allard, Dawson, De Marco, Deligny, Dolag, E. Parizot, Greisen, Kronberg, Lemoine, Medina, N. Globus, Parizot, Shinosaki, Sigl, Stanev, Zatsepin   +25 more
core   +3 more sources

Radar Polarimetry in Glaciology: Theory, Measurement Techniques, and Scientific Applications for Investigating the Anisotropy of Ice Masses

Reviews of Geophysics, Volume 63, Issue 4, December 2025.
Abstract Dielectric anisotropy in ice alters the propagation of polarized radio waves, so polarimetric radar sounding can be used to survey anisotropic properties of ice masses. Ice anisotropy is either intrinsic, associated with ice‐crystal orientation fabric (COF), or extrinsic, associated with material heterogeneity, such as bubbles, fractures, and ...
Benjamin H. Hills, T. J. Young, David A. Lilien, Esther Babcock, Nicole Bienert, Donald Blankenship, John Bradford, Giancorrado Brighi, Alex Brisbourne, Jørgen Dall, Reinhard Drews, Olaf Eisen, M. Reza Ershadi, Tamara A. Gerber, Nicholas Holschuh, Daniela Jansen, Thomas M. Jordan, Nanna B. Karlsson, Jilu Li, Carlos Martín, Kenichi Matsuoka, Daniel May, Falk M. Oraschewski, John Paden, Nicholas M. Rathmann, Neil Ross, Dustin M. Schroeder, Martin Siegert, Matthew R. Siegfried, Emma Smith, Ole Zeising   +30 more
wiley   +1 more source

Magnetic Field of Molecular Gas Measured with the Velocity Gradient Technique. II. Curved Magnetic Field in kpc-scale Bubble of NGC 628

The Astrophysical Journal
We report the detection of the ordered alignment between the magnetic field and kpc-scale bubbles in the nearby spiral galaxy, NGC 628. Applying the Velocity Gradient Technique on CO spectroscopic data from the ALMA-PHANGS, the magnetic field of NGC 628 ...
Mengke Zhao, Jianjun Zhou, Willem A. Baan, Yue Hu, A. Lazarian, Xindi Tang, Jarken Esimbek, Yuxin He, Dalei Li, Weiguang Ji, Zhengxue Chang, Kadirya Tursun   +11 more
doaj   +1 more source

Metric perturbation from inflationary magnetic field and generic bound on inflation models

, 2012
There is an observational indication of extragalactic magnetic fields. No known astrophysical process can explain the origin of such large scale magnetic fields, which motivates us to look for their origin in primordial inflation.
Jun’ichi Yokoyama, K. Sato, Teruaki Suyama, V. Mukuhanov   +3 more
core   +1 more source