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Universe
Special Issues
Advances in Understanding Astrophysical and Atomic Phenomena
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Advances in Understanding Astrophysical and Atomic Phenomena

A special issue of Universe (ISSN 2218-1997).

Deadline for manuscript submissions: closed (31 July 2021) | Viewed by 9568

Special Issue Editors

Prof. Dr. Eugene Oks

E-Mail Website
Guest Editor
Department of Physics, Auburn University, Auburn, AL 36849-5319, USA
Interests: atomic, molecular and optical physics; laser physics; plasma physics; astrophysics; nonlinear dynamics; fundamentals of quantum mechanics
Special Issues, Collections and Topics in MDPI journals
Prof. Dr. Piero Nicolini

E-Mail Website
Guest Editor
Frankfurt Institute of Advanced Studies (FIAS) and Institut für Theoretische Physik, Goethe Universitat, 60439 Frankfurt am Main, Germany
Interests: classical and quantum gravity; black holes; cosmology; mathematical methods for physics
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues, 

Astrophysical phenomena have fundamental connections to atomic phenomena—either directly or through various analogies. Theoretical and observational studies of dark matter, dark energy, the early Universe, black holes, and other large structures related to cosmology, as well as of small- and medium-size structures, such as the solar system, stellar dynamics, and galaxies, and gravitational waves, continue to be at the forefront of astrophysical research. Atomic and molecular physics currently has a broad scope of theoretical and experimental studies, including (but not limited to) atoms and molecules in various external fields (including laser fields), electronic and ionic collisions, electronic correlations in nanosystems, laser cooling of atoms and Bose–Einstein condensates, atomic processes in plasmas, chaotic phenomena in the micro-world, and quantum computing and information.

This Special Issue welcomes presentations of new theoretical and experimental results in all areas of astrophysics and cosmology and all areas of atomic and molecular physics. This Special Issue also welcomes reviews (full-size or mini-reviews) on any sub-field of these broad research areas. 

Prof. Dr. Eugene Oks
Prof. Dr. Piero Nicolini
Guest Editors

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Universe is an international peer-reviewed open access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • dark matter
  • dark energy
  • early Universe
  • cosmology
  • galaxies
  • stellar dynamics
  • solar system
  • solar and stellar flares
  • astrophysical plasmas
  • atomic processes in plasmas
  • atoms and molecules in a laser field
  • electronic and ionic collisions
  • electronic correlations in nanosystems
  • laser cooling of atoms
  • Bose–Einstein condensates
  • chaotic phenomena in the micro-world
  • quantum computing and information
  • atomic spectroscopy
  • molecular spectroscopy
  • radio- and microwave-range spectroscopy
  • infra-red spectroscopy of molecular rotations and vibrations
  • ultraviolet and visible range spectroscopy of electronic molecular processes
  • atmospheric science
  • astrophysical neutral-gas sources

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  • Greater discoverability: Special Issues support the reach and impact of scientific research. Articles in Special Issues are more discoverable and cited more frequently.
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Further information on MDPI's Special Issue polices can be found here.

Published Papers (4 papers)

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Research

13 pages, 923 KiB  
Article
From the Vector to Scalar Perturbations Addition in the Stark Broadening Theory of Spectral Lines
by Valery Astapenko, Andrei Letunov and Valery Lisitsa
Universe 2021, 7(6), 176; https://doi.org/10.3390/universe7060176 - 2 Jun 2021
Cited by 5 | Viewed by 2010
Abstract
The effect of plasma Coulomb microfied dynamics on spectral line shapes is under consideration. The analytical solution of the problem is unachievable with famous Chandrasekhar–Von-Neumann results up to the present time. The alternative methods are connected with modeling of a real ion Coulomb [...] Read more.
The effect of plasma Coulomb microfied dynamics on spectral line shapes is under consideration. The analytical solution of the problem is unachievable with famous Chandrasekhar–Von-Neumann results up to the present time. The alternative methods are connected with modeling of a real ion Coulomb field dynamics by approximate models. One of the most accurate theories of ions dynamics effect on line shapes in plasmas is the Frequency Fluctuation Model (FFM) tested by the comparison with plasma microfield numerical simulations. The goal of the present paper is to make a detailed comparison of the FFM results with analytical ones for the linear and quadratic Stark effects in different limiting cases. The main problem is connected with perturbation additions laws known to be vector for small particle velocities (static line shapes) and scalar for large velocities (the impact limit). The general solutions for line shapes known in the frame of scalar perturbation additions are used to test the FFM procedure. The difference between “scalar” and “vector” models is demonstrated both for linear and quadratic Stark effects. It is shown that correct transition from static to impact limits for linear Stark-effect needs in account of the dependence of electric field jumping frequency in FFM on the field strengths. However, the constant jumping frequency is quite satisfactory for description of the quadratic Stark-effect. The detailed numerical comparison for spectral line shapes in the frame of both scalar and vector perturbation additions with and without jumping frequency field dependence for the linear and quadratic Stark effects is presented. Full article
(This article belongs to the Special Issue Advances in Understanding Astrophysical and Atomic Phenomena)
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11 pages, 1143 KiB  
Article
Physical Acceptability of the Renyi, Tsallis and Sharma-Mittal Holographic Dark Energy Models in the f(T,B) Gravity under Hubble’s Cutoff
by Salim Harun Shekh, Pedro H. R. S. Moraes and Pradyumn Kumar Sahoo
Universe 2021, 7(3), 67; https://doi.org/10.3390/universe7030067 - 12 Mar 2021
Cited by 22 | Viewed by 2457
Abstract
In the present article, we investigate the physical acceptability of the spatially homogeneous and isotropic Friedmann–Lemâitre–Robertson–Walker line element filled with two fluids, with the first being pressureless matter and the second being different types of holographic dark energy. This geometric and material content [...] Read more.
In the present article, we investigate the physical acceptability of the spatially homogeneous and isotropic Friedmann–Lemâitre–Robertson–Walker line element filled with two fluids, with the first being pressureless matter and the second being different types of holographic dark energy. This geometric and material content is considered within the gravitational field equations of the f(T,B) (where T is the torsion scalar and the B is the boundary term) gravity in Hubble’s cut-off. The cosmological parameters, such as the Equation of State (EoS) parameter, during the cosmic evolution, are calculated. The models are stable throughout the universe expansion. The region in which the model is presented is dependent on the real parameter δ of holographic dark energies. For all δ≥4.5, the models vary from ΛCDM era to the quintessence era. Full article
(This article belongs to the Special Issue Advances in Understanding Astrophysical and Atomic Phenomena)
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12 pages, 517 KiB  
Communication
Precision Measurement Noise Asymmetry and Its Annual Modulation as a Dark Matter Signature
by Benjamin M. Roberts and Andrei Derevianko
Universe 2021, 7(3), 50; https://doi.org/10.3390/universe7030050 - 28 Feb 2021
Cited by 4 | Viewed by 1908
Abstract
Dark matter may be composed of self-interacting ultralight quantum fields that form macroscopic objects. An example of which includes Q-balls, compact non-topological solitons predicted by a range of theories that are viable dark matter candidates. As the Earth moves through the galaxy, interactions [...] Read more.
Dark matter may be composed of self-interacting ultralight quantum fields that form macroscopic objects. An example of which includes Q-balls, compact non-topological solitons predicted by a range of theories that are viable dark matter candidates. As the Earth moves through the galaxy, interactions with such objects may leave transient perturbations in terrestrial experiments. Here we propose a new dark matter signature: an asymmetry (and other non-Gaussianities) that may thereby be induced in the noise distributions of precision quantum sensors, such as atomic clocks, magnetometers, and interferometers. Further, we demonstrate that there would be a sizeable annual modulation in these signatures due to the annual variation of the Earth velocity with respect to dark matter halo. As an illustration of our formalism, we apply our method to 6 years of data from the atomic clocks on board GPS satellites and place constraints on couplings for macroscopic dark matter objects with radii R<104km, the region that is otherwise inaccessible using relatively sparse global networks. Full article
(This article belongs to the Special Issue Advances in Understanding Astrophysical and Atomic Phenomena)
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9 pages, 380 KiB  
Communication
Spectra of a Rydberg Atom in Crossed Electric and Magnetic Fields
by Andrei Letunov and Valery Lisitsa
Universe 2020, 6(10), 157; https://doi.org/10.3390/universe6100157 - 24 Sep 2020
Cited by 3 | Viewed by 2126
Abstract
Contemporary spectroscopic studies of astrophysical and laboratory plasmas frequently deal with extremely large values of principle quantum numbers of atomic systems. These atomic states are very sensitive to electric and magnetic fields of the surrounding medium. While interpreting the spectra of such excited [...] Read more.
Contemporary spectroscopic studies of astrophysical and laboratory plasmas frequently deal with extremely large values of principle quantum numbers of atomic systems. These atomic states are very sensitive to electric and magnetic fields of the surrounding medium. While interpreting the spectra of such excited atomic systems, one faces the problem of a huge array of radiative transitions between highly excited atomic levels. Moreover, external electric and magnetic fields significantly complicate the problem because of the absence of standard selection rules typical for the spherical quantization. The analytical expression in the parabolic representation for dipole matrix elements obtained by Gordon contains hyper-geometric series and it has a very complex structure. The matrix elements that involve the presence of electric and magnetic fields are calculated while using a representation closely related to the parabolic quantization on two different axes. This matrix element depends in a complex way on the transition probabilities in the parabolic coordinate system (Gordon’s formulas) and the Wigner d-functions. This circumstance leads to even greater computational difficulties. A method of simplification of these complicated expressions for transition probabilities is demonstrated. The semiclassical approximation for coordinate matrix elements (Gulayev) and recurrence properties of the Wigner d-functions are used. The Hnβ line is under consideration. Specific calculations for the transition 10–8 in the case of parallel and perpendicular fields are presented. Full article
(This article belongs to the Special Issue Advances in Understanding Astrophysical and Atomic Phenomena)
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