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Molecular clouds (MCs) are highly structured and ``turbulent''. Colliding gas streams of atomic hydrogen have been suggested as a possible source of MCs, imprinting the filamentary structure as a consequence of dynamical and thermal…

Astrophysics · Physics 2009-11-13 F. Heitsch , A. Burkert , L. Hartmann , A. D. Slyz , J. E. G. Devriendt

We introduce a sub-grid model for the non-equilibrium abundance of molecular hydrogen in cosmological simulations of galaxy formation. We improve upon previous work by accounting for the unresolved structure of molecular clouds in a…

Astrophysics of Galaxies · Physics 2015-06-19 Matteo Tomassetti , Cristiano Porciani , Emilio Romano-Diaz , Aaron D. Ludlow

Magnetic fields are ubiquitously observed in the interstellar medium (ISM) of present-day star-forming galaxies with dynamically relevant energy densities. Using three-dimensional magneto-hydrodynamic (MHD) simulations of the supernova (SN)…

We investigate the formation of molecular hydrogen (H_2) in a primordial H+He gas cloud irradiated by a power-law UV flux. We find that at high densities (>1 cm^{-3}) and low temperatures (<10^4 K), the background radiation enhances the…

Astrophysics · Physics 2009-10-28 Zoltan Haiman , Martin Rees , Abraham Loeb

Series of molecular dynamics simulations for 2-propanol-water mixtures, as a function of temperature (between freezing and room temperature) and composition (xip= 0, 0.5, 0.1 and 0.2) have been performed for temperatures reported in the…

Chemical Physics · Physics 2019-11-06 Szilvia Pothoczki , László Pusztai , Imre Bakó

The molecular species hydrogen peroxide, HOOH, is likely to be a key ingredient in the oxygen and water chemistry in the interstellar medium. Our aim with this investigation is to determine how abundant HOOH is in the cloud core {\rho} Oph…

Astrophysics of Galaxies · Physics 2011-06-02 P. Bergman , B. Parise , R. Liseau , B. Larsson , H. Olofsson , K. M. Menten , R. Güsten

We consider the survival of solid H2 in the diffuse interstellar medium, with application to grains which are small enough to qualify as dust. Consideration of only the thermal aspects of this problem leads to the familiar conclusion that…

Astrophysics of Galaxies · Physics 2015-06-16 Mark A. Walker

We examine the formation of molecular gas behind shocks in atomic gas using a chemical/dynamical model, particular emphasis is given to constraints the chemistry places on the dynamical evolution. The most important result of this study is…

The interstellar atomic hydrogen is known to be a 2-phase medium in which turbul ence plays an important r\^ole. Here we present high resolution numerical simulations describing the gas from tens of parsec down to hundreds of AU. This high…

Astrophysics · Physics 2007-05-23 P. Hennebelle , E. Audit

The formation of compact dusty clouds in diffuse interstellar medium (ISM) has been recently proposed and studied by Tsytovich et al. (2014). In the present paper, an effect of the clouds on the rate of H$\to$H$_2$ transition in the ISM is…

Astrophysics of Galaxies · Physics 2018-07-11 A. V. Ivlev , A. Burkert , A. Vasyunin , P. Caselli

We study the connection of star formation to atomic (HI) and molecular hydrogen (H$_2$) in isolated, low metallicity dwarf galaxies with high-resolution ($m_{\rm gas}$ = 4 M$_\odot$, $N_{\rm ngb}$ = 100) SPH simulations. The model includes…

Astrophysics of Galaxies · Physics 2016-03-23 Chia-Yu Hu , Thorsten Naab , Stefanie Walch , Simon C. O. Glover , Paul C. Clark

We review recent results from numerical simulations and related models of MHD turbulence in the interstellar medium (ISM) and in molecular clouds. We discuss the implications of turbulence for the processes of cloud formation and evolution,…

Astrophysics · Physics 2007-05-23 E. Vazquez-Semadeni , E. C. Ostriker , T. Passot , C. F. Gammie , J. M. Stone

We review the relevance of H2 molecules for structure formation in cosmology. Molecules are important at high redshifts, when the first collapsed structures appear with typical temperatures of a few hundred Kelvin. In these chemically…

Astrophysics · Physics 2007-05-23 Tom Abel , Zoltan Haiman

We investigate the ability of primordial gas clouds to retain molecular hydrogen (H_2) during the initial phase of the reionization epoch. We find that before the Stromgren spheres of the individual ionizing sources overlap, the UV…

Astrophysics · Physics 2009-10-28 Zoltan Haiman , Martin Rees , Abraham Loeb

In the denser and colder ($\leq$20 K) regions of the interstellar medium (ISM), near-infrared observations have revealed the presence of sub-micron sized dust grains covered by several layers of H\textsubscript{2}O-dominated ices and…

Astrophysics of Galaxies · Physics 2020-11-25 Stefano Ferrero , Lorenzo Zamirri , Cecilia Ceccarelli , Arezu Witzel , Albert Rimola , Piero Ugliengo

We generate synthetic HI Galactic plane surveys from spiral galaxy simulations which include stellar feedback processes. Compared to a model without feedback we find an increased scale height of HI emission (in better agreement with…

Astrophysics of Galaxies · Physics 2015-06-03 David M. Acreman , Clare L. Dobbs , Christopher M. Brunt , Kevin A. Douglas

We present an analytical model of the relation between the surface density of gas and star formation rate in galaxies and clouds, as a function of the presence of supersonic turbulence and the associated structure of the interstellar…

Cosmology and Nongalactic Astrophysics · Physics 2012-11-06 Florent Renaud , Katarina Kraljic , Frédéric Bournaud

Context. Radical chemical reactions on cosmic dust grains play a crucial role in forming various chemical species. Among different radicals, the hydroxyl (OH) is one of the most important ones, with a rather specific chemistry. Aims. The…

Astrophysics of Galaxies · Physics 2025-05-07 Jan Poštulka , Petr Slavíček , Johannes Kästner , Germán Molpeceres

We investigated the behavior of H$_2$, main constituent of the gas phase in dense clouds, after collision with amorphous solid water (ASW) surfaces, one of the most abundant chemical species of interstellar ices. We developed a general…

Chemical Physics · Physics 2020-03-20 G. Molpeceres , J. Kästner

There is accumulating evidence for the presence of complex molecules, including carbon-bearing and organic molecules, in the interstellar medium. Much of this evidence comes to us from studies of chemical composition, photo- and…

Earth and Planetary Astrophysics · Physics 2015-10-21 David W. Marshall , H. R. Sadeghpour