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The height of the Milky Way diffusion halo, above which cosmic-rays can freely escape the galaxy, is among the most critical, yet poorly known, parameters in cosmic-ray physics. Measurements of radioactive secondaries, such as $^{10}$Be or…

Astrophysics of Galaxies · Physics 2024-08-27 Pedro De La Torre Luque , Tim Linden

Recent advances in both the MHD turbulence theory and cosmic ray observations call for revisions in the paradigm of cosmic ray transport. We use the models of magnetohydrodynamic turbulence that were tested in numerical simulation, in which…

High Energy Astrophysical Phenomena · Physics 2013-12-02 Huirong Yan , Siyao Xu

We present the results of deep spectropolarimetry of two powerful radio galaxies at $z\sim2.5$ (4C 00.54 and 4C 23.56) obtained with the W.M. Keck II 10m telescope, aimed at studying the relative contribution of the stellar and non-stellar…

Observations of edge-on galaxies allow us to investigate the vertical extent and properties of dust, gas and stellar distributions. NGC 891 has been studied for decades and represents one of the best studied cases of an edge-on galaxy. We…

Astrophysics of Galaxies · Physics 2016-01-25 M. Bocchio , S. Bianchi , L. K. Hunt , R. Schneider

We use surface brightness contour maps of nearby edge-on spiral galaxies to determine whether extended bright radio halos are common. In particular, we test a recent model of the spatial structure of the diffuse radio continuum by…

Astrophysics of Galaxies · Physics 2015-06-23 J. Singal , A. Kogut , E. Jones , H. Dunlap

We determine the diffusion length of excess carriers in GaN by spatially resolved cathodoluminescence spectroscopy utilizing a single quantum well as carrier collector or carrier sink. Monochromatic intensity profiles across the quantum…

The radial density profiles of stellar galaxy discs can be well approximated as an exponential. Compared to this canonical form, however, the profiles in the majority of disc galaxies show downward or upward breaks at large radii.…

The formation of galaxies is significantly influenced by galactic winds, possibly driven by cosmic rays due to their long cooling times and better coupling to plasma compared to radiation. In this study, we compare the radio observations of…

Astrophysics of Galaxies · Physics 2024-10-04 H. -H. Sandy Chiu , Mateusz Ruszkowski , Timon Thomas , Maria Werhahn , Christoph Pfrommer

We present a comprehensive study about the phenomenological implications of the theory describing Galactic cosmic-ray scattering onto magnetosonic and Alfv\'enic fluctuations in the $\mathrm{GeV} - \mathrm{PeV}$ domain. We compute a set of…

High Energy Astrophysical Phenomena · Physics 2021-02-17 Ottavio Fornieri , Daniele Gaggero , Silvio Sergio Cerri , Pedro De la Torre Luque , Stefano Gabici

We have obtained two-dimensional velocity fields of the dwarf spiral galaxy NGC 2976 in Halpha and CO. The high spatial (~75 pc) and spectral (13 km/s and 2 km/s, respectively) resolution of these observations, along with our multicolor…

Astrophysics · Physics 2009-11-10 Joshua D. Simon , Alberto D. Bolatto , Adam Leroy , Leo Blitz

Understanding the transport of energetic cosmic rays belongs to the most challenging topics in astrophysics. Diffusion due to scattering by electromagnetic fluctuations is a key process in cosmic-ray transport. The transition from a…

High Energy Astrophysical Phenomena · Physics 2020-09-02 P. Reichherzer , J. Becker Tjus , E. G. Zweibel , L. Merten , M. J. Pueschel

We study transport of GeV cosmic rays (CRs) in a set of high-resolution TIGRESS magnetohydrodynamic simulations of the star-forming interstellar medium (ISM). Our local disk patch models sample a wide range of gas surface densities,…

Astrophysics of Galaxies · Physics 2025-09-04 Ronan Hix , Lucia Armillotta , Eve Ostriker , Chang-Goo Kim

Recently, Sun et al. (2008) published new Galactic 3D-models of magnetic fields in the disk and halo of the Milky Way and the distribution of cosmic-ray electron density by taking into account the thermal electron density model NE2001 by…

Astrophysics of Galaxies · Physics 2015-05-20 Xiaohui Sun , Wolfgang Reich

Starburst galaxies are efficient $\gamma$-ray producers, because their high supernova rates generate copious cosmic ray (CR) protons, and their high gas densities act as thick targets off which these protons can produce neutral pions and…

High Energy Astrophysical Phenomena · Physics 2020-02-26 Mark R. Krumholz , Roland M. Crocker , Siyao Xu , A. Lazarian , M. T. Rosevear , Jasper Bedwell-Wilson

Recent measurements of cosmic ray proton and helium spectra show a hardening above a few hundreds of GeV. This excess is hard to understand in the framework of the conventional models of Galactic cosmic ray production and propagation. We…

High Energy Astrophysical Phenomena · Physics 2013-10-01 Guilhem Bernard , Timur Delahaye , Yong-Yeon Keum , Wei Liu , Pierre Salati , Richard Taillet

We have obtained deep, long-slit spectroscopy along the major axis of NGC 6166, the cD galaxy in the cluster Abell 2199, in order to measure the kinematics of intracluster starlight at large radii. The velocity dispersion rises beyond a few…

The AUGER Collaboration has recently published the precise energy spectrum of cosmic rays above 1 EeV, which exhibits rich and interesting features. These features provide an opportunity to investigate the galactic propagation and…

High Energy Astrophysical Phenomena · Physics 2024-04-16 Weikang Gao , Dan Li , Wei Liu , Hua Yue , Hongbo Hu

The diffusion of galactic cosmic rays (CR) is considered. It is anticipated that the nonlinear MHD cascade sets the power-law spectrum of turbulence from the principle scale 100 pc to much smaller scales. We found that the dissipation of…

Astrophysics · Physics 2007-05-23 V. S. Ptuskin , F. C. Jones , I. V. Moskalenko , V. N. Zirakashvili

Galaxy formation models predict that local galaxies are surrounded by hot X-ray-emitting halos, which are technically difficult to detect due to their extended and low surface brightness nature. Previous X-ray studies have mostly focused on…

Astrophysics of Galaxies · Physics 2025-03-14 Lin He , Zhiyuan Li , Meicun Hou , Min Du , Taotao Fang , Wei Cui

The study of radio emission in starburst dwarf galaxies provides a unique opportunity to investigate the mechanisms responsible for the amplification and transport of magnetic fields. Local dwarfs are often considered proxies for…