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The addition of metals to any gas can significantly alter its evolution by increasing the rate of radiative cooling. In star-forming environments, enhanced cooling can potentially lead to fragmentation and the formation of low-mass stars,…

Astrophysics · Physics 2009-11-13 Britton D. Smith , Steinn Sigurdsson , Tom Abel

The excitation of the filamentary gas structures surrounding giant elliptical galaxies at the center of cool-core clusters, a.k.a BCGs (brightest cluster galaxies), is key to our understanding of active galactic nucleus feedback, and of the…

It is well-known that photoionization is the major mechanism powering nebulae emission-lines. For about 30 years, numerical simulations using photoionization codes have been employed to analyze HII regions, planetary nebulae and active…

Astrophysics · Physics 2007-05-23 Sueli M. Viegas

We have studied the thermal instabilities in the context of Active Galactic Nuclei (AGN), addressing the cases of thin and thick (stratified) X-ray illuminated media. For that, we have compared the behaviour of different models in pressure…

Astrophysics · Physics 2007-05-23 A. C. Goncalves , S. Collin , A. -M. Dumont

We present and test chemical models for three-dimensional hydrodynamical simulations of galaxies. We explore the effect of changing key parameters such as metallicity, radiation and non-equilibrium versus equilibrium metal cooling…

Astrophysics of Galaxies · Physics 2016-05-04 Stefano Bovino , Tommaso Grassi , Pedro R. Capelo , Dominik R. G. Schleicher , R. Banerjee

The thermal history of the intergalactic medium is full of extremely useful data in the field of astrophysics and cosmology. In other words, by examining this environment in different redshifts, the effects of cosmology and astrophysics can…

Cosmology and Nongalactic Astrophysics · Physics 2023-06-23 S. Mobina Hosseini , Bahareh Soleimanpour Salmasi , Seyed Sajad Tabasi , Javad T. Firouzjaee

Nonequilibrium (time-dependent) cooling rates and ionization state calculations are presented for low-density gas enriched with heavy elements (metals) and photoionized by external ultraviolet/X-ray radiation. We consider a wide range of…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-19 Evgenii O. Vasiliev

We extend the non-equilibrium model for the chemical and thermal evolution of diffuse interstellar gas presented in Richings et al. (2014) to account for shielding from the UV radiation field. We attenuate the photochemical rates by dust…

Astrophysics of Galaxies · Physics 2015-06-19 Alexander J. Richings , Joop Schaye , Benjamin D. Oppenheimer

We present a linear analysis of acoustic and thermo-reactive instabilities in a diffuse gas, photoionized and heated by a radiation field, cooled by collisional excitation of hydrogen and metal lines. The hydrogen recombination reaction has…

Astrophysics · Physics 2009-10-28 Edvige Corbelli , Andrea Ferrara

First we present a recently developed 3D chemodynamical code for galaxy evolution from the K**2 collaboration. It follows the evolution of all components of a galaxy such as dark matter, stars, molecular clouds and diffuse interstellar…

Astrophysics · Physics 2009-11-10 R. Spurzem , P. Berczik , G. Hensler , Ch. Theis , P. Amaro-Seoane , M. Freitag , A. Just

Current and upcoming cosmological observations allow us to probe structures on smaller and smaller scales, entering highly nonlinear regimes. In order to obtain theoretical predictions in these regimes, large cosmological simulations have…

Processing by interstellar photons affects the composition of the icy mantles on interstellar grains. The rate of photodissociation in solids differs from that of molecules in the gas phase. The aim of this work was to determine an average,…

Astrophysics of Galaxies · Physics 2018-05-16 Juris Kalvans

We investigate insterstellar gas spheres by determining the metric functions, the material distribution, and the features of particle orbits in terms of stability and geodesics. An exact solution of the Einstein's equations for interstellar…

General Relativity and Quantum Cosmology · Physics 2017-08-21 Dániel Barta

We present our current update on the gas-phase chemical reactions and spectral lines of TiO in the spectral synthesis code Cloudy. For this purpose, we have added 229 Ti-related reactions in the chemical network. In addition, we consider…

Astrophysics of Galaxies · Physics 2024-07-31 Gargi Shaw , Gary J. Ferland , Phillip Stancil , Ryan Porter

We present a modified TREESPH code to model galaxies in 3d. The model includes a multi-phase description of the interstellar medium which combines two numerical techniques. A diffuse warm/hot gas phase is modelled by SPH while a sticky…

Astrophysics · Physics 2009-11-10 S. Harfst , C. Theis , G. Hensler

Bailey & Basu (2014) show analysis of density and mass-to-flux ratio maps for simulations with either an ionisation profile which takes into account photoionisation (step-like profile) or a cosmic ray only ionisation profile. We extend this…

Solar and Stellar Astrophysics · Physics 2017-03-15 Nicole D. Bailey , Shantanu Basu , Paola Caselli

We present new calculations of the photoionization of interstellar matter within ~5 pc of the Sun (which we refer to as the Complex of Local Interstellar Clouds or CLIC) by directly observed radiation sources including nearby hot stars and…

Astrophysics · Physics 2009-11-06 Jonathan D. Slavin , Priscilla C. Frisch

We present a time-dependent photoionization code that combines self-consistently metal evolution and dust destruction under an intense X-ray UV radiation field. Firstly, we extend the mathematical formulation of the time-dependent evolution…

Astrophysics · Physics 2009-11-07 Rosalba Perna , Davide Lazzati

With the high-resolution spectroscopy now available in the optical and satellite UV, it is possible to determine the neutral/ionized column density ratios for several different elements in a single cloud. Assuming ionization equilibrium for…

Astrophysics · Physics 2009-11-06 Joseph C. Weingartner , B. T. Draine

We survey the current situation regarding chemical modelling of the synthesis of molecules in the interstellar medium. The present state of knowledge concerning the rate coefficients and their uncertainties for the major gas-phase processes…