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We investigate a non-equilibrium ionization state and an electron-ion two-temperature structure of the intracluster medium in the merging galaxy cluster, 1E0657-56 (the Bullet cluster), using a series of N-body and hydrodynamic simulations.…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-30 Takuya Akahori , Kohji Yoshikawa

We investigate a non-equilibrium ionization state and an electron-ion two-temperature structure of the intracluster medium (ICM) in merging galaxy clusters using a series of N-body and hydrodynamic simulations. Mergers with various sets of…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-14 Takuya Akahori , Kohji Yoshikawa

The densities in the outer regions of clusters of galaxies are very low, and the collisional timescales are very long. As a result, heavy elements will be under-ionized after they have passed through the accretion shock. We have studied…

High Energy Astrophysical Phenomena · Physics 2015-05-20 Ka-Wah Wong , Craig L. Sarazin , Li Ji

The analysis of X-ray and Sunyaev-Zel\'dovich measurements of the intracluster medium (ICM) assumes that electrons are in thermal equilibrium with ions in the plasma. However, electron-ion equilibration timescales can be comparable to the…

Cosmology and Nongalactic Astrophysics · Physics 2015-08-20 Camille Avestruz , Daisuke Nagai , Erwin T. Lau , Kaylea Nelson

Recent X-ray observations of galaxy clusters show that the distribution of intra-cluster medium (ICM) metallicity is remarkably uniform in space and time. In this paper, we analyse a large sample of simulated objects, from poor groups to…

Galaxy cluster mergers drive powerful shock fronts that heat the intracluster medium (ICM) and accelerate particles, redistributing the energy in a merger. A665 is one of only a few clusters with such a powerful shock ($\mathcal{M}\sim$3),…

Cosmology and Nongalactic Astrophysics · Physics 2025-10-21 Christian Norseth , Daniel R. Wik , Craig L. Sarazin , Ming Sun , Fabio Gastaldello

During transient events such as major solar eruptions, the plasma can be far from the equilibrium ionization state because of rapid heating or cooling. Non-equilibrium ionization~(NEI) is important in rapidly evolving systems where the…

Solar and Stellar Astrophysics · Physics 2019-07-17 Jin-Yi Lee , John C. Raymond , Katharine K. Reeves , Chengcai Shen , Yong-Jae Moon , Yeon-Han Kim

We present high-resolution cosmological hydrodynamic simulations of three galaxy clusters employing a two-temperature model for the intracluster medium. We show that electron temperatures in cluster outskirts are significantly lower than…

Cosmology and Nongalactic Astrophysics · Physics 2009-08-11 Douglas H. Rudd , Daisuke Nagai

The ionization state of the gas in the dynamic solar chromosphere can depart strongly from the instantaneous statistical equilibrium commonly assumed in numerical modeling. We improve on earlier simulations of the solar atmosphere that only…

Solar and Stellar Astrophysics · Physics 2016-02-03 Thomas Peter Golding , Jorrit Leenaarts , Mats Carlsson

Astrophysical shocks or bursts from a photoionizing source can disturb the typical collisional plasma found in galactic interstellar media or the intergalactic medium. The spectrum emitted by this plasma contains diagnostics that have been…

High Energy Astrophysical Phenomena · Physics 2015-05-19 Randall K. Smith , John P. Hughes

We investigate a non-equilibrium ionization state and two-temperature structure of the intracluster medium in the linked region of Abell 399/401, using a series of N-body + SPH simulations, and find that there exist significant shock layers…

Astrophysics · Physics 2015-05-13 Takuya Akahori , Kohji Yoshikawa

Results from a large set of hydrodynamical SPH simulations of galaxy clusters in a flat LCDM cosmology are used to investigate the metal enrichment and heating of the ICM. The physical modeling of the gas includes radiative cooling, star…

Astrophysics · Physics 2009-11-07 R. Valdarnini

The ionization of hydrogen in the solar chromosphere and transition region does not obey LTE or instantaneous statistical equilibrium because the timescale is long compared with important hydrodynamical timescales, especially of…

Astrophysics · Physics 2009-11-13 J. Leenaarts , M. Carlsson , V. Hansteen , R. J. Rutten

We present a suite of one-dimensional spherically-symmetric hydrodynamic simulations that study the atomic ionization structure of galactic outflows. We track the ionization state of the outflowing gas with a non-equilibrium atomic…

Astrophysics of Galaxies · Physics 2019-05-01 William J Gray , Evan Scannapieco , Matthew D. Lehnert

(abridged) We have studied the effects of electron-ion non-equipartition in the outer regions of relaxed clusters for a wide range of masses in the \LambdaCDM cosmology using one-dimensional hydrodynamic simulations. The effects of the…

Cosmology and Nongalactic Astrophysics · Physics 2010-10-14 Ka-Wah Wong , Craig L. Sarazin

Simulations of the formation of galaxies, as well as ionisation models used to interpret observations of quasar absorption lines, generally either assume ionisation equilibrium or ignore the presence of the extra-galactic background (EGB)…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-15 Benjamin D. Oppenheimer , Joop Schaye

We present an analysis of the iron abundance in the hot gas surrounding galaxy groups and clusters. To do this, we first compile and homogenise a large dataset of 79 low-redshift (|z| = 0.03) systems (159 individual measurements) from the…

Astrophysics of Galaxies · Physics 2016-11-23 Robert M. Yates , Peter A. Thomas , Bruno M. B. Henriques

Abell 754 is a galaxy cluster in which an ongoing merger is evident on the plane of the sky, from the southeast to the northwest. We study the spatial variation of the X-ray spectra observed with Suzaku along the merging direction,…

High Energy Astrophysical Phenomena · Physics 2016-03-07 Shota Inoue , Kiyoshi Hayashida , Shutaro Ueda , Ryo Nagino , Hiroshi Tsunemi , Katsuji Koyama

Hydrodynamical SPH simulations of galaxy clusters are used to investigate the metal enrichment of the intracluster medium. The final metallicity abundances of the simulated clusters are determined according to the numerical resolution and a…

Astrophysics · Physics 2007-05-23 R. Valdarnini

Heating of charged particles via collisionless shocks, while ubiquitous in the universe, is an intriguing yet puzzling plasma phenomenon. One outstanding question is how electrons and ions approach an equilibrium after they were heated to…

High Energy Astrophysical Phenomena · Physics 2024-05-16 Masahiro Ichihashi , Aya Bamba , Yuichi Kato , Satoru Katsuda , Hiromasa Suzuki , Tomoaki Kasuga , Hirokazu Odaka , Kazuhiro Nakazawa
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