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A first-order liquid-liquid phase transition in high-pressure hydrogen between molecular and atomic fluid phases has been predicted in computer simulations using ab initio molecular dynamics approaches. However, experiments indicate that…

Statistical Mechanics · Physics 2007-05-23 Kris T. Delaney , Carlo Pierleoni , D. M. Ceperley

We present a simulation of the cosmic evolution of the atomic and molecular phases of the cold hydrogen gas in about 3e7 galaxies, obtained by post-processing the virtual galaxy catalog produced by (De Lucia et al. 2007) on the Millennium…

Cosmology and Nongalactic Astrophysics · Physics 2011-02-11 D. Obreschkow , D. Croton , G. De Lucia , S. Khochfar , S. Rawlings

The recent EDGES measurements of the global 21-cm signal from the cosmic dawn suggest that the kinetic temperature of the inter-galactic medium (IGM) might be significantly lower compared to its expected value. The colder IGM directly…

Cosmology and Nongalactic Astrophysics · Physics 2020-10-02 Kanan K. Datta , Aritra Kundu , Ankit Paul , Ankita Bera

With the cosmic ray observations made by the Voyager 1 spacecraft outside the dominant modulating influence of the heliosphere, the comparison of computed galactic spectra with experimental data at lower energies is finally possible.…

High Energy Astrophysical Phenomena · Physics 2016-01-20 Driaan Bisschoff , Marius S. Potgieter

We present new calculations of Stark broadened profiles for neutral helium lines using computer simulations that include some important aspects aimed at better representing the dynamical environment of the helium atom. These include the…

Solar and Stellar Astrophysics · Physics 2020-10-07 Patrick Tremblay , Alain Beauchamp , Pierre Bergeron

Supernovae of Type IIb contain large fractions of helium and traces of hydrogen, which can be observed in the early and late spectra. Estimates of the hydrogen and helium mass and distribution are mainly based on early-time spectroscopy and…

High Energy Astrophysical Phenomena · Physics 2015-05-19 I. Maurer , P. Mazzali , S. Taubenberger , S. Hachinger

We have measured dissociative recombination of HCl+ with electrons using a merged beams configuration at the heavy-ion storage ring TSR located at the Max Planck Institute for Nuclear Physics in Heidelberg, Germany. We present the measured…

Instrumentation and Methods for Astrophysics · Physics 2013-10-23 O. Novotný , A. Becker , H. Buhr , C. Domesle , W. Geppert , M. Grieser , C. Krantz , H. Kreckel , R. Repnow , D. Schwalm , K. Spruck , J. Stützel , B. Yang , A. Wolf , D. W. Savin

We study binary and the recently discovered process of ternary He-assisted recombination of H3+ ions with electrons in a low temperature afterglow plasma. The experiments are carried out over a broad range of pressures and temperatures of…

We propose a method to study the epoch of reionization based on the possible observation of 2p--2s fine structure lines from the neutral hydrogen outside the cosmological H {\sc ii} regions enveloping QSOs and other ionizing sources in the…

Astrophysics · Physics 2009-06-23 Shiv. K. Sethi , Ravi Subrahmanyan , D. Anish Roshi

Observations of helium and hydrogen emission lines from metal-poor extragalactic H II regions provide an independent method for determining the primordial helium abundance, Y_p. Traditionally, the emission lines employed are in the visible…

Cosmology and Nongalactic Astrophysics · Physics 2015-07-15 Erik Aver , Keith A. Olive , Evan D. Skillman

Missing transverse momentum is a crucial observable for physics at hadron colliders, being the only constraint on the kinematics of "invisible" objects such as neutrinos and hypothetical dark matter particles. Computing missing transverse…

The emission from galactic black holes and Seyfert galaxies is generally understood in term of two-phase models (Haardt and Maraschi 1991, 1993). Such models postulate that a hot plasma coexists with relatively colder material in the inner…

Astrophysics · Physics 2009-11-10 Julien Malzac , Anne-Marie Dumont , Martine Mouchet

We present a simple two-dimensional model of the indirect dissociative recombination process. The model has one electronic and one nuclear degree of freedom and it can be solved to high precision, without making any physically motivated…

Locating recombination hotspots in genomic data is an important but difficult task. Current methods frequently rely on estimating complicated models at high computational cost. In this paper we develop an extremely fast, scalable method for…

Applications · Statistics 2015-12-08 Jordan Rodu , Shane T. Jensen

We introduce a radiative transfer code module for the magnetohydrodynamical adaptive mesh refinement code FLASH 4. It is coupled to an efficient chemical network which explicitly tracks the three hydrogen species H, H_2, H+ as well as C+…

Instrumentation and Methods for Astrophysics · Physics 2015-09-30 C. Baczynski , S. C. O. Glover , R. S. Klessen

We aim at studying the effect of radial motions on the spectrum emitted by moving prominences in the helium resonance lines and at facilitating the interpretation of observations, in order to improve our understanding of these dynamic…

Astrophysics · Physics 2007-05-23 Nicolas Labrosse , Pierre Gouttebroze , Jean-Claude Vial

We introduce non-equilibrium molecular hydrogen chemistry into the radiation hydrodynamics code Ramses-RT. This is an adaptive mesh refinement grid code with radiation hydrodynamics that couples the thermal chemistry of hydrogen and helium…

Astrophysics of Galaxies · Physics 2018-09-07 Sarah Nickerson , Romain Teyssier , Joakim Rosdahl

Density inhomogeneity in the intergalactic medium (IGM) can boost the recombination rate of ionized gas substantially, affecting the growth of HII regions during reionization. Previous attempts to quantify this effect typically failed to…

Cosmology and Nongalactic Astrophysics · Physics 2016-11-09 Hyunbae Park , Paul R. Shapiro , Jun-hwan Choi , Naoki Yoshida , Shingo Hirano , Kyungjin Ahn

Precision spectroscopy of simple atomic systems has refined our understanding of the fundamental laws of quantum physics. In particular, helium spectroscopy has played a crucial role in describing two-electron interactions, determining the…

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