Intergalactic Magnetic Field and Arrival Direction of Ultra-High-Energy Protons (2009)
Ryu, Dongsu, Das, Santabrata, Kang, Hyesung
We studied how the intergalactic magnetic field (IGMF) affects the propagation of super-GZK protons that originate from extragalactic sources within the local GZK sphere. Toward this end, we set up...
Ryu, Dongsu, Kang, Hyesung, Das, Santabrata
Ultrahigh energy cosmic rays (UHECRs) are believed to originate from astrophysical sources, which should trace the large scale structure (LSS) of the universe. On the other hand, the magnetic field...
Self-Similar Evolution of Cosmic-Ray Modified Shocks: The Cosmic-Ray Spectrum (2009)
Kang, Hyesung, Ryu, Dongsu, Jones, T. W.
We use kinetic simulations of diffusive shock acceleration (DSA) to study the time-dependent evolution of plane, quasi-parallel, cosmic-ray (CR) modified shocks. Thermal leakage injection of low...
Shock Waves in the Large-Scale Structure of the Universe (2008)
Cosmological shock waves are induced during hierarchical formation of large-scale structure in the universe. Like most astrophysical shocks, they are collisionless, since they form in the tenuous...
Turbulence and Magnetic Fields in the Large Scale Structure of the Universe (2008)
Ryu, Dongsu, Kang, Hyesung, Cho, Jungyeon, Das, Santabrata
The nature and origin of turbulence and magnetic fields in the intergalactic space are important problems that are yet to be understood. We propose a scenario in which turbulent flow motions are...
COSMIC RAYS AND THEIR RADIATIVE PROCESSES IN NUMERICAL COSMOLOGY (2008)
Dongsu Ryu, Francesco Miniati, Tom W. Jones, Hyesung Kang
para calcular, de manera simplificada, la aceleración y el transporte de los rayos cósmicos. La rutina fue diseñada para seguir de manera explícita la aceleración difusiva en choques y la...
Propagation of UHE Protons through Magnetized Cosmic Web (2008)
Das, Santabrata, Kang, Hyesung, Ryu, Dongsu, Cho, Jungyeon
If ultra-high-energy cosmic rays (UHECRs) originate from extragalactic sources, understanding the propagation of charged particles through the magnetized large scale structure (LSS) of the universe...
Feedback from Multiple Supernova Explosions inside a Wind-Blown Bubble (2007)
We study the evolution of multiple supernova (SN) explosions inside a pre-exiting cavity blown by winds from massive progenitor stars. Hydrodynamic simulations in one-dimensional spherical geometry,...
Propagation of UHE protons through a magnetized large scale structure (2007)
Kang, Hyesung, Das, Santabrata, Ryu, Dongsu, Cho, Jungyeon
The propagation of UHECRs is affected by the intergalactic magnetic fields that were produced during the course of the large scale structure formation of the universe. We adopt a novel model where...
Self-Similar Evolution of Cosmic-Ray-Modified Quasi-Parallel Plane Shocks (2007)
Using an improved version of the previously introduced CRASH (Cosmic Ray Acceleration SHock) code, we have calculated the time evolution of cosmic-ray (CR) modified quasi-parallel plane shocks for...
Kang, Hyesung, Ryu, Dongsu, Cen, Renyue, Ostriker, J. P.
Cosmological shock waves result from supersonic flow motions induced by hierarchical clustering of nonlinear structures in the universe. These shocks govern the nature of cosmic plasma through...
Cosmic ray acceleration at blast waves from type Ia supernovae (2007)
We have calculated the cosmic ray (CR) acceleration at young remnants from Type Ia supernovae expanding into a uniform interstellar medium (ISM). Adopting quasi-parallel magnetic fields, gasdynamic...
Cosmic rays and their radiative processes in numerical cosmology (2006)
Dongsu Ryu, Francesco Miniati, Tom W. Jones, Hyesung Kang
Cosmic rays and their radiative processes in numerical cosmology
Baek, Chang Hyun, Ryu, Dongsu, Kang, Hyesung, Kim, Jongsoo
Thermal-gravitational instability (TGI) is studied in the protogalactic environment. We extend our previous work, where we found that dense clumps first form out of hot background gas by thermal...
Numerical Studies of Diffusive Shock Acceleration at Spherical Shocks (2006)
We have developed a cosmic ray (CR) shock code in one dimensional spherical geometry with which the particle distribution, the gas flow and their nonlinear interaction can be followed numerically in...
Baek, Chang Hyun, Kang, Hyesung, Kim, Jongsoo, Ryu, Dongsu
We study thermal-gravitational instability in simplified models for protogalactic halos using three-dimensional hydrodynamic simulations. The simulations followed the evolution of gas with radiative...
Shock-Heated Gas in the Large Scale Structure of the Universe (2004)
Kang, Hyesung, Ryu, Dongsu, Cen, Renyue, Song, Doojong
Cosmological shock waves play a major role in heating baryonic gas in the large scale structure of the universe. In this contribution we study the shock-heated gas in connection with shocks...
Cosmological Shock Waves and Their Role in the Large Scale Structure of the Universe (2003)
Ryu, Dongsu, Kang, Hyesung, Hallman, Eric, Jones, T. W.
We study the properties of cosmological shock waves identified in high-resolution, N-body/hydrodynamic simulations of a $\Lambda$CDM universe and their role on thermalization of gas and acceleration...
Acceleration of Cosmic Rays at Cosmic Shocks (2003)
Nonthermal particles can be produced due to incomplete thermalization at collisionless shocks and further accelerated to very high energies via diffusive shock acceleration. In a previous study we...
Structure shocks as a source of cosmic rays in clusters (2003)
Jones, T. W., Miniati, Francesco, Ryu, Dongsu, Kang, Hyesung, Hallmann, Eric J.
Acceleration of Cosmic Rays at Large Scale Cosmic Shocks in the Universe (2002)
Cosmological hydrodynamic simulations of large scale structure in the universe have shown that accretion shocks and merger shocks form due to flow motions associated with the gravitational collapse...
Clusters of Galaxies: Shock Waves and Cosmic Rays (2002)
Recent observations of galaxy clusters in radio and X-ray indicate that cosmic rays and magnetic fields may be energetically important in the intracluster medium. According to the estimates based on...
Cosmic Rays in Clusters of Galaxies (2002)
Biermann, Peter L., Enßlin, Torsten A., Kang, Hyesung, Lee, Hyesook, Ryu, Dongsu
We argue that clusters of galaxies have an intergalactic medium, which is permeated by strong magnetic fields and also has a contribution of pressure from cosmic rays. These two components of total...
Two-Dimensional Axisymmetric Collapse of Thermally Unstable Primordial Clouds (2002)
Baek, Chang Hyun, Kang, Hyesung, Ryu, Dongsu
We have performed two-dimensional hydrodynamic simulations of the collapse of isolated axisymmetric clouds condensing via radiative cooling in a primordial background gas. In order to study the...
Numerical Studies of Cosmic Ray Injection and Acceleration (2002)
Kang, Hyesung, Jones, T. W., Gieseler, U. D. J.
A numerical scheme that incorporates a thermal leakage injection model into a combined gas dynamics and cosmic ray (CR, hereafter) diffusion-convection code has been developed. The particle injection...
Structure Shocks as a Source of Cosmic Rays in Clusters (2002)
Jones, T. W., Miniati, Francesco, Ryu, Dongsu, Kang, Hyesung, Hallman, Eric J.
Shocks are a ubiquitous consequence of cosmic structure formation, and they play an essential role in heating galaxy cluster media. Virtually all of the gas in clusters has been processed by one or...
Miniati, Francesco, Jones, T. W., Kang, Hyesung, Ryu, Dongsu
We study the generation and distribution of high energy electrons in cosmic environment and their observational consequences by carrying out the first cosmological simulation that includes directly...
Miniati, Francesco, Ryu, Dongsu, Kang, Hyesung, Jones, T. W.
We investigate the production of cosmic ray (CR) protons at cosmological shocks by performing, for the first time, numerical simulations of large scale structure formation that include directly the...
Present Status of Diffusive Shock Acceleration (2000)
Diffusive shock acceleration (DSA) is now widely accepted as the model to explain the production of cosmic rays (CRs) in a wide range of astrophysical environments. Despite initial successes of the...
Time Evolution of Cosmic-Ray Modified Plane Shocks (2000)
Kang, Hyesung, Jones, T. W., LeVeque, R. J., Shyue, K. M.
We have developed a novel computer code designed to follow the evolution of cosmic-ray modified shocks, including the full momentum dependence of the particles for a realistic diffusion coefficient...
Time dependent cosmic-ray shock acceleration with self-consistent injection (2000)
Gieseler, U. D. J., Jones, T. W., Kang, Hyesung
One of the key questions to understanding the efficiency of diffusive shock acceleration of the cosmic rays (CRs) is the injection process from thermal particles. A self-consistent injection model...
Winds and Shocks in Galaxy Clusters: Shock Acceleration on an Intergalactic Scale (2000)
Jones, T. W., Miniati, Francesco, Ryu, Dongsu, Kang, Hyesung
We review the possible roles of large scale shocks as particle accelerators in clusters of galaxies. Recent observational and theoretical work has suggested that high energy charged particles may...
Formation of Proto-Globular Cluster Clouds by Thermal Instability (2000)
Kang, Hyesung, Lake, George, Ryu, Dongsu
Many models of globular cluster formation assume the presence of cold dense clouds in early universe. Here we re-examine the Fall & Rees (1985) model for formation of proto-globular cluster clouds...
Properties of Cosmic Shock Waves in Large Scale Structure Formation (2000)
Miniati, Francesco, Ryu, Dongsu, Kang, Hyesung, Jones, T. W., Cen, Renyue, Ostriker, Jeremiah P.
We have examined the properties of shock waves in simulations of large scale structure formation for two cosmological scenarios (a SCDM and a LCDM with Omega =1). Large-scale shocks result from...
Miniati, Francesco, Ryu, Dongsu, Jones, T. W., Kang, Hyesung
We investigate the dynamical importance of a newly recognized possible source of significant feedback generated during structure formation; namely cosmic ray (CR) pressure. We present evidence for...
Cosmic rays and their radiative processes in numerical cosmology (2000)
Jones , Tom W., Kang , Hyesung, Miniati , Francesco, Ryu , Dongsu
A cosmological hydrodynamic code is described, which includes a routine to compute cosmic ray acceleration and transport in a simpli ed way. The routine was designed to follow explicitly di usive...
Cosmic Rays and Their Radiative Processes in Numerical Cosmology (1999)
Ryu, Dongsu, Miniati, Francesco, Jones, Tom W., Kang, Hyesung
A cosmological hydrodynamic code is described, which includes a routine to compute cosmic ray acceleration and transport in a simplified way. The routine was designed to follow explicitly diffusive...
Large Cosmic Shock Waves as Sites for Particle Acceleration (1999)
Miniati, Francesco, Ryu, Dongsu, Kang, Hyesung, Jones, T. W.
The properties of cosmic shock waves are studied through numerical simulations in two cosmological scenarios (SCDM and LCDM). The scaling relations for the average radius and velocity associated with...
Ion injection and acceleration at modified shocks (1999)
Gieseler, U. D. J., Jones, T. W., Kang, Hyesung
The theory of diffusive particle acceleration explains the spectral properties of the cosmic rays below energies of approx. 10^6 GeV as produced at strong shocks in supernova remnants (SNR's). To...
Cosmic Magnetic Fields in Large Scale Filaments and Sheets (1998)
Ryu, Dongsu, Kang, Hyesung, Biermann, Peter L.
We consider the possibility that cosmic magnetic field, instead of being uniformly distributed, is strongly correlated with the large scale structure of the universe. Then, the observed rotational...
$10^{51}$ Ergs: The Evolution of Shell Supernova Remnants (1997)
Jones, T. W., Rudnick, Lawrence, Jun, Byung-Il, Borkowski, Kazimierz J., Dubner, Gloria, Frail, Dale A., ...
This paper reports on a workshop hosted by the University of Minnesota, March 23-26, 1997. It addressed fundamental dynamical issues associated with the evolution of shell supernova remnants and the...
The supergalactic structure and the origin of the highest energy cosmic rays (1997)
Biermann, Peter L., Kang, Hyesung, Ryu, Dongsu
The recent discoveries of several reliable events of high energy cosmic rays at an energy above 10^20 eV raise questions about their path through the nearby universe. The two analyses of the Haverah...
Cosmic Structure of Magnetic Fields (1997)
Biermann, Peter L., Kang, Hyesung, Rachen, Joerg P., Ryu, Dongsu
The simulations of the formation of cosmological structure allows to determine the spatial inhomogeneity of cosmic magnetic fields. Such simulations, however, do not give an absolute number for the...
Cosmic Shock Waves on Large Scales of the Universe (1997)
In the standard theory of the large scale structure formation, matter accretes onto high density perturbations via gravitational instability. Collisionless dark matter forms caustics around such...
Contributions to the Cosmic Ray Flux above the Ankle: Clusters of Galaxies (1996)
Kang, Hyesung, Rachen, Jörg P., Biermann, Peter L.
Motivated by the suggestion of Kang, Ryu \& Jones (1996) that particles can be accelerated to high energies via diffusive shock acceleration process at the accretion shocks formed by the infalling...
We report simulations of diffusive particle acceleration in oblique magnetohydrodynamical (MHD) shocks. These calculations are based on extension to oblique shocks of a numerical model for ``thermal...
Close Encounters between a Neutron Star and a Main-Sequence Star (1996)
Lee, Hyung Mok, Kim, Sungsoo S., Kang, Hyesung
We have examined consequences of strong tidal encounters between a neutron star and a normal star using SPH as a possible formation mechanism of isolated recycled pulsars in globular clusters. We...
Contributions To The Cosmic Ray Flux Above The Ankle: Clusters Of Galaxies (1996)
Hyesung Kang, Jörg P. Rachen, Peter L. Biermann
Assuming that particles can be accelerated to high energies via diffusive shock acceleration process at the accretion shocks formed by the infalling flow toward the clusters of galaxies, we have...
Cosmic Shock Waves on Large Scales of the Universe (1996)
In the standard theory of the large scale structure formation, matter accretes onto high density perturbations via gravitational instability. Collisionless dark matter forms caustics around such...
Supersonic Collisions between Two Gas Streams (1995)
Lee, Hyung Mok, Kang, Hyesung, Ryu, Dongsu
A star around a massive black hole can be disrupted tidally by the gravity of the black hole. Then, its debris may form a precessing stream which may even collide with itself. In order to understand...
Kang, Hyesung, Ryu, Dongsu, Jones, T. W.
Three-dimensional hydrodynamic simulations of large scale structure in the Universe have shown that accretion shocks form during the gravitational collapse of one-dimensional caustics, and that...
Background X-ray Emission from Hot Gas in CDM and CDM+Lambda Universes: Spectral Signatures (1995)
Cen, Renyue, Kang, Hyesung, Ostriker, Jeremiah P., Ryu, Dongsu
We present a new treatment of two popular models for the growth of structure, examining the X-ray emission from hot gas with allowance for spectral line emission from various atomic species,...
Direct comparisons of diffusive particle acceleration numerical simulations have been made against Monte Carlo and hybrid plasma simulations by Ellison {\it et. al.} (1993) and against observations...
Hot Gas in the CDM Scenario: X-Ray Clusters from a High Resolution Numerical Simulation (1994)
Kang, Hyesung, Cen, Renyue, Ostriker, Jeremiah P., Ryu, Dongsu
We exmaine the distribution of hot gas in a standard CDM model of the universe using high resolution hydrodynamic simulations. Adopting standard parameters determined from COBE and light element...
A Comparison of Cosmological Hydrodynamic Codes (1994)
Kang, Hyesung, Ostriker, Jeremiah P., Cen, Renyue, Ryu, Dongsu, Hernquist, Lars, Evrard, August E., ...
We present a detailed comparison of the simulation results of various cosmological hydrodynamic codes. Starting with identical initial conditions based on the Cold Dark Matter scenario for the growth...