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We examine the thermodynamic state and cooling of the low-$z$ Circum-Galactic Medium (CGM) in five FIRE-2 galaxy formation simulations of Milky Way-mass galaxies. We find that the CGM in these simulations is generally multiphase and…

At low temperatures, the main coolant in primordial gas is molecular hydrogen, H2. Recent work has shown that primordial gas that is not collapsing gravitationally but is cooling from an initially ionized state forms hydrogen deuteride, HD,…

Astrophysics · Physics 2009-11-13 S. C. O. Glover , T. Abel

Atoms and molecules, and in particular CO, are important coolants during the evolution of interstellar star-forming gas clouds. The presence of dust grains, which allow many chemical reactions to occur on their surfaces, strongly impacts…

Solar and Stellar Astrophysics · Physics 2015-06-17 S. Hocuk , S. Cazaux , M. Spaans

The composition of the outer 100 m of a neutron star sets the heat flux that flows outwards from the core. For an accreting neutron star in an X-ray transient, the thermal quiescent flux depends sensitively on the amount of hydrogen and…

Astrophysics · Physics 2009-11-07 Edward F. Brown , Lars Bildsten , Philip Chang

We present simulations of cosmic reionization and reheating from $z=18$ to $z=5$, investigating the role of stars (emitting soft UV-photons), nuclear black holes (BHs, with power-law spectra), X-ray binaries (XRBs, with hard X-ray dominated…

Cosmology and Nongalactic Astrophysics · Physics 2020-09-16 Marius B. Eide , Benedetta Ciardi , Luca Graziani , Philipp Busch , Yu Feng , Tiziana Di Matteo

We use numerical simulations to investigate the importance of HD formation and cooling on the first generation of metal-free stars in a LCDM cosmology. We have implemented and tested non-equilibrium HD chemistry in an adaptive mesh…

Astrophysics · Physics 2009-11-13 Ian D. McGreer , Greg L. Bryan

In our current galaxy formation paradigm, high-redshift galaxies are predominantly fuelled by accretion of cool, metal-poor gas from the intergalactic medium. Hydrodynamical simulations predict that this material should be observable in…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-16 Neil H. M. Crighton , Joseph F. Hennawi , J. Xavier Prochaska

The discrepancy between expected and observed cooling rates of X-ray emitting gas has led to the {\it cooling flow problem} at the cores of clusters of galaxies. A variety of models have been proposed to model the observed X-ray spectra and…

Astrophysics of Galaxies · Physics 2019-10-15 Mohammad H. Zhoolideh Haghighi , Niayesh Afshordi , Habib. G. Khosroshahi

The inhomogeneous cooling state describing the hydrodynamic behavior of a freely evolving granular gas strongly confined between two parallel plates is studied, using a Boltzmann kinetic equation derived recently. By extending the idea of…

Statistical Mechanics · Physics 2019-12-20 J. Javier Brey , M. I. García de Soria , P. Maynar

We investigate ionization and heating of gas in the dense, shielded clumps/cores of molecular clouds bathed by an influx of energetic, charged cosmic rays (CRs). These molecular clouds have complex structures, with substantial variation in…

Astrophysics of Galaxies · Physics 2021-06-02 Ellis R. Owen , Alvina Y. L. On , Shih-Ping Lai , Kinwah Wu

Local thermal instability can plausibly explain the formation of multiphase gas in many different astrophysical environments, but the theory is only well understood in the optically thin limit of the equations of radiation hydrodynamics…

High Energy Astrophysical Phenomena · Physics 2022-09-07 Daniel Proga , Tim Waters , Sergei Dyda , Zhaohuan Zhu

In circumstellar disks or shells it is often assumed that gas and dust temperatures are equal where the latter is determined by radiative equilibrium. This paper deals with the question whether this assumption is applicable for tenous…

Astrophysics · Physics 2009-11-06 Inga Kamp , Gerd-Jan van Zadelhoff

The pervasive presence of warm gas in galaxy halos suggests that the circumgalactic medium (CGM) is multiphase in its ionization structure and complex in its kinematics. Some recent state-of-the-art cosmological galaxy simulations predict…

We study the structure and evolution of neutron stars (NS) the interiors of which are modeled using microscopic approaches and constrained by the condition that the equation of state (EoS) of matter extrapolated to high densities should not…

Astrophysics · Physics 2008-12-18 Hovik Grigorian

A few results that indicate the presence of temperature variations in gaseous nebulae are reviewed. The evidence is based on: a) temperatures derived from different methods, and b) on comparisons of abundances predicted by models of…

Astrophysics · Physics 2007-05-23 Manuel Peimbert , Antonio Peimbert

We present hydrodynamical simulations of the formation of galaxies in the mass range 10^9 - 10^13 solar masses, with the focus on the efficiency of gas cooling. The effect of a background UV radiation field, and the effect of metal…

Astrophysics · Physics 2007-05-23 John Hultman , Daniel Kaellander

The ionization mechanism of the low-ionization gas in quiescent red sequence galaxies has been a long-standing puzzle. Direct temperature measurements would put strong constraints on this issue. We carefully selected a sample of quiescent…

Astrophysics of Galaxies · Physics 2018-08-15 Renbin Yan

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 present a new model for the X-ray properties of the intracluster medium that explicitly includes heating of the gas by the energy released during the evolution of cluster galaxies. We calculate the evolution of clusters by combining the…

Astrophysics · Physics 2009-10-31 R. G. Bower , A. J. Benson , C. G. Lacey , C. M. Baugh , S. Cole , C. S. Frenk

We introduce and test a new and highly efficient method for treating the thermal and radiative effects influencing the energy equation in SPH simulations of star formation. The method uses the density, temperature and gravitational…

Astrophysics · Physics 2009-11-13 D. Stamatellos , A. P. Whitworth , T. Bisbas , S. Goodwin