Results 61 to 70 of about 19,051 (197)

Ultra High Energy Cosmic Rays: propagation in the Galaxy and anisotropy [PDF]

, 2000
We considered propagation of Ultra High Energy Cosmic Rays (UHECR) through the galaxy. We investigated models with sources of UHECR distributed in the same way as Cold Dark Matter (CDM) in a self-consistent way, taking into account both extra-galactic ...
Kalashev, O. E., Kuzmin, V. A., Semikoz, D. V.   +2 more
core   +2 more sources

A Comparative Study of VTEC Estimates Derived From S/X VLBI and VGOS Observations

Space Weather, Volume 23, Issue 12, December 2025.
Abstract The ionosphere, which strongly varies in time and space, is one of the largest error sources for microwave measurements, if not accounted for accurately. Especially for single‐frequency observations, precise ionospheric models are needed to correct for the ionospheric delays. This study explores the utility of Very Long Baseline Interferometry
Arno Rüegg, Grzegorz Kłopotek, Benedikt Soja   +2 more
wiley   +1 more source

Kiloparsec-Scale Jets in FR I Radio Galaxies and the Gamma-Ray Background

, 2005
We discuss the contribution of kiloparsec-scale jets in FR I radio galaxies to the diffuse gamma-ray background radiation. The analyzed gamma-ray emission comes from inverse-Compton scattering of starlight photon fields by the ultrarelativistic electrons
Aharonian F., Bloom E. D., Falle S. A. E. G., J. Kataoka, Komissarov S. S., Nikishov A. I., Padovani P., Parma P., Protheroe R. J., Protheroe R. J., T. M. Kneiske, Weferling B., Ł. Stawarz   +12 more
core   +1 more source

HEAD IN THE STARS, FEET ON THE GROUND: Scale and Astronomy Initiatives in Southern Africa

Cultural Anthropology, Volume 40, Issue 4, Page 571-596, November 2025.
ABSTRACT This article explores the evolution of radio astronomy in South Africa and Madagascar, focusing on how “scale” functions as both a way of understanding the world and marking differences in existence. In outer space research, the ground is crucial but often overlooked.
HANNA NIEBER, DAVIDE CHINIGÒ
wiley   +1 more source

UHECRs Propagation and Their Multimessengers: Upper Limits and the Impact of the Extragalactic Magnetic Field

The Astrophysical Journal
The detection of high-energy astrophysical multimessengers establishes a connection between ultra-high-energy cosmic rays (UHECRs) and powerful cosmic accelerators.
Rodrigo Sasse, Rubens Costa Jr., Adriel G.B. Mocellin, Carlos H. Coimbra-Araujo, R. C. Dos Anjos   +4 more
doaj   +1 more source

Extragalactic Zeeman Detections in OH Megamasers [PDF]

, 2008
We have measured the Zeeman splitting of OH megamaser emission at 1667 MHz from five (ultra)luminous infrared galaxies ([U]LIRGs) using the 305 m Arecibo telescope and the 100 m Green Bank Telescope.
Burn B. J., Carl Heiles, Eliot Quataert, Kazes I., Killeen N. E. B., Randell J., Staveley-Smith L., Staveley-Smith L., Timothy Robishaw   +8 more
core   +1 more source

Magnetic fields of extragalactic radio sources: Testing cosmological models [PDF]

Astronomy Letters, 2006
Based on the synchrotron radiation mechanism with self-absorption, we estimate the magnetic fields of compact (∼0 . ″ 001) structures of radio galaxies. Using a model radial dependence of the magnetic field, we estimate the field strength near the event horizon of a supermassive black hole. The latter
Yu. N. Gnedin, M. Yu. Piotrovich
openaire   +1 more source

Deep Space Network Radio Science and Ground‐Based Planetary Radar in the Next Decade

Radio Science, Volume 60, Issue 7, July 2025.
Abstract The Deep Space Network (DSN) has been a core operational element of NASA's crewed and robotic exploration of the Solar System since the early 1960s. The primary role of the DSN has been to acquire telemetry and navigation data, but over the years, its radiometric and radar capabilities have expanded to form a system for obtaining unique ...
R. S. Park, J. E. Riedel, N. Rodriguez‐Alvarez, M. Brozovic, L. A. M. Benner, P. Vergados, D. Buccino, C. S. Jacobs, L. S. Locke, S. W. Asmar, R. Castano, T. J. W. Lazio, J. Jao, C. Lee   +13 more
wiley   +1 more source

Magnetic fields in extragalactic radio sources

The Astrophysical Journal, 1981
Distributions of total intensity and linear polarization have been calculated for synchrotron radiation from a variety of magnetic fields which may occur in extragalactic radio sources, assuming that the energy distributions of radiating electrons are uniform and isotropic. Analytical solutions are derived for helical and transverse self-similar fields
openaire   +1 more source

GRB 221009A: A Light Dark Matter Burst or an Extremely Bright Inverse Compton Component?

The Astrophysical Journal, 2023
Gamma-ray bursts (GRBs) have been considered as potential very high energy photon emitters due to the large amount of energy released as well as the strong magnetic fields involved in their jets.
M. M. González, D. Avila Rojas, A. Pratts, S. Hernández-Cadena, N. Fraija, R. Alfaro, Y. Pérez Araujo, J. A. Montes   +7 more
doaj   +1 more source