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We present improved fits to our treatment of suppression of dielectronic recombination at intermediate densities. At low densities, most recombined excited states eventually decay to the ground state, and therefore the total dielectronic…

Measuring the time it takes to remove an electron from an atom or molecule during photoionization using newly developed attosecond spectroscopies has been a focus of many recent experiments. However, the outcome of such measurement depends…

Atomic Physics · Physics 2017-03-08 Lisa Torlina , Olga Smirnova

Multiphoton ionization provides a clear window into the nature of electron correlations in the helium atom. In the present study, the final state energy range extends up to the region near the $N=2$ and $N=3$ ionization thresholds, where…

Atomic Physics · Physics 2021-03-10 Yimeng Wang , Chris H. Greene

We present results from the first self-consistent multi-fluid simulations of chromospheric magnetic reconnection in a weakly ionized reacting plasma. We simulate two dimensional magnetic reconnection in a Harris current sheet with a…

Plasma Physics · Physics 2014-03-04 James E. Leake , Vyacheslav S. Lukin , Mark G. Linton , Eric T. Meier

The measurements of the 21-cm brightness temperature fluctuations from the neutral hydrogen at the Epoch of Reionization (EoR) should inaugurate the next generation of cosmological observables. In this respect, many works have concentrated…

Cosmology and Nongalactic Astrophysics · Physics 2013-01-10 Sebastien Clesse , Laura Lopez-Honorez , Christophe Ringeval , Hiroyuki Tashiro , Michel H. G. Tytgat

Efficient and accurate simulations of the reionization epoch are crucial to exploring the vast uncharted parameter space that will soon be constrained by measurements of the 21 cm power spectrum. One of these parameters, $R_{\rm max}$, is…

Cosmology and Nongalactic Astrophysics · Physics 2022-04-20 Frederick B. Davies , Steven R. Furlanetto

We present a detailed model of the discrete X-ray spectroscopic features expected from steady-state, low-density photoionized plasmas. We apply the Flexible Atomic Code (FAC) to calculate all of the necessary atomic data for the full range…

Astrophysics · Physics 2007-05-23 A. Kinkhabwala , E. Behar , M. Sako , M. F. Gu , S. M. Kahn , F. B. S. Paerels

We apply time-dependent R-matrix theory to study inner-shell ionization of C atoms in ultra-short high-frequency light fields with a photon energy between 170 and 245 eV. At an intensity of 10$^{17}$ W/cm$^2$, ionization is dominated by…

Atomic Physics · Physics 2015-08-12 H. F. Rey , H. W. van der Hart

We present new calculations of the inhomogeneous process of cosmological reionization by carefully following the radiative transfer in pre-computed hydrodynamical simulations of galaxy formation. These new computations represent an…

Astrophysics · Physics 2009-11-07 Alexei O. Razoumov , Michael L. Norman , Tom Abel , Douglas Scott

Photoionization of a cold atomic sample offers intriguing possibilities to observe collective effects at extremely low temperatures. Irradiation of a rubidium condensate and of cold rubidium atoms within a magneto-optical trap with laser…

Atomic Physics · Physics 2009-11-07 D. Ciampini , M. Anderlini , J. H. Müller , F. Fuso , O. Morsch , J. W. Thomsen , E. Arimondo

We have used semi-numerical simulations of reionization to study the behaviour of the power spectrum of the EoR 21-cm signal in redshift space. We have considered two models of reionization, one which has homogeneous recombination (HR) and…

Cosmology and Nongalactic Astrophysics · Physics 2013-09-05 Suman Majumdar , Somnath Bharadwaj , T. Roy Choudhury

Photoionization of neutral atomic sulfur in the ground and metastable states was studied experimentally at a photon energy resolution of 44 meV FWHM. Relative cross section measurements were recorded by using tunable vacuum ultraviolet…

Earth and Planetary Astrophysics · Physics 2015-06-23 Mathias Barthel , Roman Flesch , Eckart Rühl , Brendan M. McLaughlin

Crank-Nicolson (C-N) Method combined with $ B $-spline basis set can be used in both time-dependent and time-independent calculations of the photoionization cross sections of atoms and molecules. For time-independent systems, it is found…

Atomic Physics · Physics 2014-09-15 Xue-Bin Bian

Ultrafast processes in matter, such as the electron emission following light absorption, can now be studied using ultrashort light pulses of attosecond duration ($10^{-18}$s) in the extreme ultraviolet spectral range. The lack of spectral…

The CHIANTI atomic database provides sets of assessed data used for simulating spectral observations of astrophysical plasmas. This article describes updates that will be released as version~10.1 of the database. A key component of CHIANTI…

Atomic Physics · Physics 2023-08-23 Kenneth Dere , Giulio Del Zanna , Peter Young , Enrico Landi

We present here a detailed calculation of opacities for Fe~XVII at the physical conditions corresponding to the base of the Solar convection zone. Many ingredients are involved in the calculation of opacities. We review the impact of each…

Solar and Stellar Astrophysics · Physics 2021-08-04 F. Delahaye , C. P. Connor , R. T. Smith , N. R. Badnell

We introduce a new method that allows one to obtain an analytical cross section for the laser-assisted electron-ion collision in a closed form. As an example we perform a calculation for the hydrogen laser-assisted recombination. The…

Atomic Physics · Physics 2011-05-19 Gavriil Shchedrin , Alexander Volberg

Large-scale polarization of the cosmic microwave background measured by the WMAP satellite requires a mean optical depth to Thomson scattering, tau_e ~ 0.17. The reionization of the universe must therefore have begun at relatively high…

Astrophysics · Physics 2009-11-07 B. Ciardi , A. Ferrara , S. D. M. White

In a recombining plasma the metastable states are known to accumulate population thereby slowing down the recombination process. We show that an account of the doubly-excited autoionizing states, formed due to collisional recombination of…

Plasma Physics · Physics 2009-11-07 Yu. V. Ralchenko , Y. Maron