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Water (H2O) ice is an important solid constituent of many astrophysical environments. To comprehend the role of such ices in the chemistry and evolution of dense molecular clouds and comets, it is necessary to understand the freeze-out,…

Cooling a range of molecules to ultracold temperatures (<1 mK) is a difficult but important challenge in molecular physics and chemistry. Collective cavity cooling of molecules is a promising method that does not rely on molecular energy…

Atomic Physics · Physics 2012-05-11 Guangjiong Dong , Chang Wang , Weiping Zhang

Recent laboratory experiments on interstellar dust analogues have shown that H_2 formation on dust grain surfaces is efficient in a range of grain temperatures below 20 K. These results indicate that surface processes may account for the…

Astrophysics · Physics 2009-11-13 Hagai B. Perets , Ofer Biham

We study the impact of molecular (${\rm H_2}$) and atomic (HI) hydrogen cooling on the galaxy formation threshold. We calculate the fraction of dark matter (DM) halos that exceeds a critical mass required for star formation,…

Astrophysics of Galaxies · Physics 2025-04-09 Ethan O. Nadler

We study steady, homogeneous and subsonic cooling flows in poor clusters of galaxies in light of the recent proposal that radiative cooling of the intracluster gas can explain the observations of the `entropy floor' and other related X-ray…

Astrophysics · Physics 2009-11-07 Biman B. Nath

Context. In dense clouds, hydrogenation reactions on icy dust grains are key in the formation of molecules, like formaldehyde, methanol, and complex organic molecules (COMs). These species form through the sequential hydrogenation of CO…

Solar and Stellar Astrophysics · Physics 2018-09-28 K. -J. Chuang , G. Fedoseev , D. Qasim , S. Ioppolo , E. F. van Dishoeck , H. Linnartz

We show theoretically that ultracold hydrogen atoms have very favorable properties for sympathetic cooling of molecules to microkelvin temperatures. We calculate the potential energy surfaces for spin-polarized interactions of H atoms with…

Atomic Physics · Physics 2013-11-20 Maykel L. Gonzalez-Martinez , Jeremy M. Hutson

Galactic winds are crucial to the cosmic cycle of matter, transporting material out of the dense regions of galaxies. Observations show the coexistence of different temperature phases in such winds, which is not easy to explain. We present…

Modern particle detectors crucially depend on efficient cooling systems. Two-phase carbon dioxide (CO$_2$) is a suitable solution as a cooling agent. This publication presents the observations and results of investigations of horizontal and…

Instrumentation and Detectors · Physics 2023-12-19 Alexander Siegfanz , Wolfgang Wagner , Uwe Janoske

We study the effects of HD molecules on thermochemical evolution of the primordial gas behind shock waves, possibly arised in the process of galaxy formation. We find the critical shock velocity when deuterium transforms efficiently into HD…

Astrophysics · Physics 2009-11-11 E. O. Vasiliev , Yu. A. Shchekinov

Recently, laser cooling methods have been extended from atoms to molecules. The complex rotational and vibrational energy level structure of molecules makes laser cooling difficult, but these difficulties have been overcome and molecules…

Atomic Physics · Physics 2019-02-18 M. R. Tarbutt

It has been shown that HD molecules can form efficiently in metal-free gas collapsing into massive protogalactic halos at high redshift. The resulting radiative cooling by HD can lower the gas temperature to that of the cosmic microwave…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-19 Jemma Wolcott-Green , Zoltán Haiman

The direct laser cooling of neutral diatomic molecules in molecular beams suggests that trapped molecular ions can also be laser cooled. The long storage time and spatial localization of trapped molecular ions provides the opportunity for…

2d hydrodynamical simulations are performed to examine the evaporation and condensation processes of giant molecular clouds in the hot phase of the interstellar medium. The evolution of cold and dense clouds is calculated in the subsonic…

Astrophysics · Physics 2009-10-31 Wolfgang Vieser , Gerhard Hensler

I summarize four of the most important areas of uncertainty in the study of the chemistry and cooling of gas with zero or very low metallicity. These are: i) the importance and effects of HD cooling in primordial gas; ii) the importance of…

Astrophysics · Physics 2008-11-26 S. C. O. Glover

We probe the physical conditions in high-redshift damped Ly-alpha systems using the observed molecular fraction and the rotational excitation of molecular hydrogen. We report two new detections of H2 at z = 2.402 and 1.989 toward,…

Astrophysics · Physics 2009-11-13 P. Noterdaeme , C. Ledoux , P. Petitjean , F. Le Petit , R. Srianand , A. Smette

The radiative cooling time of hot gas in the cool cores of many galaxy clusters and massive elliptical galaxies drops in the centre to below 100 million years. The mass cooling rates inferred from simple modelling of X-ray observations of…

Astrophysics of Galaxies · Physics 2024-11-07 L. R. Ivey , A. C. Fabian , J. S. Sanders , C. Pinto , G. J. Ferland , S. Walker , J. Jiang

We investigate the uncertainties affecting the temperature profiles of dense cores of interstellar clouds. In regions shielded from external ultraviolet radiation, the problem is reduced to the balance between cosmic ray heating, line…

Astrophysics of Galaxies · Physics 2015-05-30 M. Juvela , N. Ysard

We investigate a mechanism for accelerating cool (10$^4$ K) clouds in the circumgalactic medium (CGM) with cosmic rays (CRs), possibly explaining some characteristics of observed high velocity clouds (HVCs). Enforcing CRs to stream down…

Astrophysics of Galaxies · Physics 2019-07-31 Joshua Wiener , Ellen G. Zweibel , Mateusz Ruszkowski

The first generation of protogalaxies likely formed out of primordial gas via H2-cooling in cosmological minihalos with virial temperatures of a few 1000K. However, their abundance is likely to have been severely limited by feedback…

Astrophysics · Physics 2009-11-07 S. Peng Oh , Zoltan Haiman
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