Astronomy and Computing最新文献

{"title":"Temporal variation of atmospheric electric field in comparison with solar terrestrial activities during the 24th solar cycle","authors":"S. Faiz Gurmani ,&nbsp;N. Ahmad ,&nbsp;R. Kalsoom ,&nbsp;S. Shahzada ,&nbsp;M. Awais ,&nbsp;M. Ali Shah","doi":"10.1016/j.ascom.2024.100882","DOIUrl":"10.1016/j.ascom.2024.100882","url":null,"abstract":"<div><div>Solar activities play an important role in the variation of the Atmospheric Electric Field (AEF), and affect the Global Electric Circuit (GEC). The relationship between the variation of the AEF and solar activities is focused in the present study. It includes the variation in the AEF with respect to sunspot numbers, direct and indirect radiations, and solar flares during the decline phase of solar cycle 24 from 2015–2019 for Islamabad (ISL) observatory in detail, and partially for Muzaffarabad (MZF) observatory. A few of them had good relationship with the atmospheric electric field. The solar eclipse effect on the atmospheric electric field for the Muzaffarabad station is also presented in this work. A significant increase was observed during the eclipse period which led to decrease in electrical conductivity of atmospheric electric field as compared to alternate days for the same period.</div></div>","PeriodicalId":48757,"journal":{"name":"Astronomy and Computing","volume":"49 ","pages":"Article 100882"},"PeriodicalIF":1.9,"publicationDate":"2024-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142420006","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A comprehensive analysis of observational cosmology in f(Q) gravity with deep learning and MCMC method","authors":"L.K. Sharma ,&nbsp;S. Parekh ,&nbsp;A.K. Yadav ,&nbsp;N. Goyal","doi":"10.1016/j.ascom.2024.100892","DOIUrl":"10.1016/j.ascom.2024.100892","url":null,"abstract":"<div><div>Our goal in this study is to build FRW cosmological models inside the <span><math><mrow><mi>f</mi><mrow><mo>(</mo><mi>Q</mi><mo>)</mo></mrow></mrow></math></span> theory of gravity framework by using Bayesian statistics and deep learning method. We investigate the universe’s accelerating behaviour for a specific version of the <span><math><mrow><mi>f</mi><mrow><mo>(</mo><mi>Q</mi><mo>)</mo></mrow></mrow></math></span> gravity model using a novel, straightforward parameterization of the Hubble parameter in the form <span><math><mrow><mi>H</mi><mo>=</mo><msub><mrow><mi>H</mi></mrow><mrow><mn>0</mn></mrow></msub><msup><mrow><mrow><mo>(</mo><mn>1</mn><mo>+</mo><mi>z</mi><mo>)</mo></mrow></mrow><mrow><mn>1</mn><mo>+</mo><msub><mrow><mi>q</mi></mrow><mrow><mn>0</mn></mrow></msub><mo>−</mo><msub><mrow><mi>q</mi></mrow><mrow><mn>1</mn></mrow></msub></mrow></msup><mi>e</mi><mi>x</mi><mi>p</mi><mrow><mo>(</mo><msub><mrow><mi>q</mi></mrow><mrow><mn>1</mn></mrow></msub><mi>z</mi><mo>)</mo></mrow></mrow></math></span>. The corresponding free parameters in <span><math><mrow><mi>H</mi><mrow><mo>(</mo><mi>z</mi><mo>)</mo></mrow></mrow></math></span> are limited between 1<span><math><mi>σ</mi></math></span> and 2<span><math><mi>σ</mi></math></span> confidence bounds using the <span><math><msup><mrow><mi>χ</mi></mrow><mrow><mn>2</mn></mrow></msup></math></span>-minimization procedure. The results show that all the numbers we got are in the ballpark of what cosmological observations would predict. In our model, we examined the physical behaviour of the cosmos using characteristics such as energy density, pressure, and equation of state. We analysed kinematic factors including Hubble parameter, acceleration parameter, and universe age in our model. In our concept, the deceleration parameter <span><math><mrow><mi>q</mi><mrow><mo>(</mo><mi>z</mi><mo>)</mo></mrow></mrow></math></span> represents the universe’s transition from deceleration to acceleration. We employ a novel approach for parameter estimation by utilizing a mixed neural network (MNN) that combines artificial neural networks (ANN) and mixture density networks (MDN). This new methodology leverages the strengths of ANN, MDN, and MNN to enhance the accuracy of parameter estimation.</div></div>","PeriodicalId":48757,"journal":{"name":"Astronomy and Computing","volume":"49 ","pages":"Article 100892"},"PeriodicalIF":1.9,"publicationDate":"2024-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142593533","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"On detection of BaO molecular lines in sunspot spectrum","authors":"P. Sriramachandran ,&nbsp;S.H. Nivash","doi":"10.1016/j.ascom.2024.100891","DOIUrl":"10.1016/j.ascom.2024.100891","url":null,"abstract":"&lt;div&gt;&lt;h3&gt;Context&lt;/h3&gt;&lt;div&gt;Spectral lines of diatomic molecules are perfect tools for studying the structure of sunspots and their temperature layers and magnetic sensitive absorption features, which are typically higher than in atomic lines. The integrated intensities of a few bands in the rotational structure of the astrophysically significant &lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;msup&gt;&lt;mi&gt;A&lt;/mi&gt;&lt;mn&gt;1&lt;/mn&gt;&lt;/msup&gt;&lt;msup&gt;&lt;mrow&gt;&lt;mstyle&gt;&lt;mi&gt;Σ&lt;/mi&gt;&lt;/mstyle&gt;&lt;/mrow&gt;&lt;mo&gt;+&lt;/mo&gt;&lt;/msup&gt;&lt;mo&gt;−&lt;/mo&gt;&lt;msup&gt;&lt;mi&gt;X&lt;/mi&gt;&lt;mn&gt;1&lt;/mn&gt;&lt;/msup&gt;&lt;msup&gt;&lt;mrow&gt;&lt;mstyle&gt;&lt;mi&gt;Σ&lt;/mi&gt;&lt;/mstyle&gt;&lt;/mrow&gt;&lt;mo&gt;+&lt;/mo&gt;&lt;/msup&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt;and &lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;mi&gt;A&lt;/mi&gt;&lt;msup&gt;&lt;mrow&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mo&gt;′&lt;/mo&gt;&lt;mn&gt;1&lt;/mn&gt;&lt;/mrow&gt;&lt;/msup&gt;&lt;mstyle&gt;&lt;mi&gt;Π&lt;/mi&gt;&lt;/mstyle&gt;&lt;mo&gt;−&lt;/mo&gt;&lt;msup&gt;&lt;mi&gt;X&lt;/mi&gt;&lt;mn&gt;1&lt;/mn&gt;&lt;/msup&gt;&lt;msup&gt;&lt;mrow&gt;&lt;mstyle&gt;&lt;mi&gt;Σ&lt;/mi&gt;&lt;/mstyle&gt;&lt;/mrow&gt;&lt;mo&gt;+&lt;/mo&gt;&lt;/msup&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt; systems of barium monoxide (BaO) have been measured experimentally using band spectra. An analysis of the prominent lines of (0, 0; 1, 1; 2, 2) bands of &lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;msup&gt;&lt;mi&gt;A&lt;/mi&gt;&lt;mn&gt;1&lt;/mn&gt;&lt;/msup&gt;&lt;msup&gt;&lt;mrow&gt;&lt;mstyle&gt;&lt;mi&gt;Σ&lt;/mi&gt;&lt;/mstyle&gt;&lt;/mrow&gt;&lt;mo&gt;+&lt;/mo&gt;&lt;/msup&gt;&lt;mo&gt;−&lt;/mo&gt;&lt;msup&gt;&lt;mi&gt;X&lt;/mi&gt;&lt;mn&gt;1&lt;/mn&gt;&lt;/msup&gt;&lt;msup&gt;&lt;mrow&gt;&lt;mstyle&gt;&lt;mi&gt;Σ&lt;/mi&gt;&lt;/mstyle&gt;&lt;/mrow&gt;&lt;mo&gt;+&lt;/mo&gt;&lt;/msup&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt;transition and (0, 0; 1, 1; 2, 2) bands of &lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;mi&gt;A&lt;/mi&gt;&lt;msup&gt;&lt;mrow&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mo&gt;′&lt;/mo&gt;&lt;mn&gt;1&lt;/mn&gt;&lt;/mrow&gt;&lt;/msup&gt;&lt;mstyle&gt;&lt;mi&gt;Π&lt;/mi&gt;&lt;/mstyle&gt;&lt;mo&gt;−&lt;/mo&gt;&lt;msup&gt;&lt;mi&gt;X&lt;/mi&gt;&lt;mn&gt;1&lt;/mn&gt;&lt;/msup&gt;&lt;msup&gt;&lt;mrow&gt;&lt;mstyle&gt;&lt;mi&gt;Σ&lt;/mi&gt;&lt;/mstyle&gt;&lt;/mrow&gt;&lt;mo&gt;+&lt;/mo&gt;&lt;/msup&gt;&lt;mspace&gt;&lt;/mspace&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt;transition with those of sunspot umbral spectrum. The effective rotational temperatures of the &lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;mi&gt;A&lt;/mi&gt;&lt;msup&gt;&lt;mrow&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mo&gt;′&lt;/mo&gt;&lt;mn&gt;1&lt;/mn&gt;&lt;/mrow&gt;&lt;/msup&gt;&lt;mstyle&gt;&lt;mi&gt;Π&lt;/mi&gt;&lt;/mstyle&gt;&lt;mo&gt;−&lt;/mo&gt;&lt;msup&gt;&lt;mi&gt;X&lt;/mi&gt;&lt;mn&gt;1&lt;/mn&gt;&lt;/msup&gt;&lt;msup&gt;&lt;mrow&gt;&lt;mstyle&gt;&lt;mi&gt;Σ&lt;/mi&gt;&lt;/mstyle&gt;&lt;/mrow&gt;&lt;mo&gt;+&lt;/mo&gt;&lt;/msup&gt;&lt;mspace&gt;&lt;/mspace&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt;transition of BaO in the sunspot umbral spectrum are found to be in the range of 1600 K to 3200 K.&lt;/div&gt;&lt;/div&gt;&lt;div&gt;&lt;h3&gt;Aims&lt;/h3&gt;&lt;div&gt;An analysis of BaO prominent rotational molecular lines of &lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;msup&gt;&lt;mi&gt;A&lt;/mi&gt;&lt;mn&gt;1&lt;/mn&gt;&lt;/msup&gt;&lt;msup&gt;&lt;mrow&gt;&lt;mstyle&gt;&lt;mi&gt;Σ&lt;/mi&gt;&lt;/mstyle&gt;&lt;/mrow&gt;&lt;mo&gt;+&lt;/mo&gt;&lt;/msup&gt;&lt;mo&gt;−&lt;/mo&gt;&lt;msup&gt;&lt;mi&gt;X&lt;/mi&gt;&lt;mn&gt;1&lt;/mn&gt;&lt;/msup&gt;&lt;msup&gt;&lt;mrow&gt;&lt;mstyle&gt;&lt;mi&gt;Σ&lt;/mi&gt;&lt;/mstyle&gt;&lt;/mrow&gt;&lt;mo&gt;+&lt;/mo&gt;&lt;/msup&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt;and &lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;mi&gt;A&lt;/mi&gt;&lt;msup&gt;&lt;mrow&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mo&gt;′&lt;/mo&gt;&lt;mn&gt;1&lt;/mn&gt;&lt;/mrow&gt;&lt;/msup&gt;&lt;mstyle&gt;&lt;mi&gt;Π&lt;/mi&gt;&lt;/mstyle&gt;&lt;mo&gt;−&lt;/mo&gt;&lt;msup&gt;&lt;mi&gt;X&lt;/mi&gt;&lt;mn&gt;1&lt;/mn&gt;&lt;/msup&gt;&lt;msup&gt;&lt;mrow&gt;&lt;mstyle&gt;&lt;mi&gt;Σ&lt;/mi&gt;&lt;/mstyle&gt;&lt;/mrow&gt;&lt;mo&gt;+&lt;/mo&gt;&lt;/msup&gt;&lt;mspace&gt;&lt;/mspace&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt;transition with those of sunspot umbral spectral lines. To find the significant values of radiative transition parameters, vibrational temperature and the effective rotational temperature of the molecule in celestial objects.&lt;/div&gt;&lt;/div&gt;&lt;div&gt;&lt;h3&gt;Methods&lt;/h3&gt;&lt;div&gt;Calibrated the rotational structure of molecular band heads and lines for and &lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;msup&gt;&lt;mi&gt;A&lt;/mi&gt;&lt;mn&gt;1&lt;/mn&gt;&lt;/msup&gt;&lt;msup&gt;&lt;mrow&gt;&lt;mstyle&gt;&lt;mi&gt;Σ&lt;/mi&gt;&lt;","PeriodicalId":48757,"journal":{"name":"Astronomy and Computing","volume":"49 ","pages":"Article 100891"},"PeriodicalIF":1.9,"publicationDate":"2024-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142652656","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Computation of bulk viscous pressure with observational constraints via scalar field in the General relativity and f(Q) gravity","authors":"A. Dixit ,&nbsp;S. Gupta ,&nbsp;A. Pradhan ,&nbsp;S. Krishnannair","doi":"10.1016/j.ascom.2024.100885","DOIUrl":"10.1016/j.ascom.2024.100885","url":null,"abstract":"<div><div>The present article deals with the isotropic cosmological model of <span><math><mrow><mi>f</mi><mrow><mo>(</mo><mi>Q</mi><mo>)</mo></mrow></mrow></math></span> gravity filled with bulk viscous fluid, where <span><math><mi>Q</mi></math></span> is the non-metricity term and it is responsible for the gravitational interaction. Aside from the tachyon and quintessence scalar fields, the modified Einstein’s field equations have been resolved through the application of the power law form of the expansion. In this model, the Markov chain Monte Carlo (MCMC) analysis method has been utilized to obtained the best-fit value of the model parameter and it confirms that the model satisfies the recent observational data. We have also examined the EoS parameter for bulk viscosity in these cosmological contexts and it has been determined that <span><math><msub><mrow><mi>ω</mi></mrow><mrow><mi>e</mi><mi>f</mi><mi>f</mi></mrow></msub></math></span> will be located in the phantom region. The correspondence between bulk pressure and the reconstructed <span><math><msub><mrow><mi>ω</mi></mrow><mrow><mi>r</mi><mi>e</mi><mi>c</mi><mo>,</mo><mi>Q</mi></mrow></msub></math></span> in f(Q) gravity has also been addressed. In the presence of holographic Ricci dark energy, the reconstructed <span><math><mrow><mi>f</mi><mrow><mo>(</mo><mi>Q</mi><mo>)</mo></mrow></mrow></math></span> gravity yields a transition from the quintessence era into phantom era.</div></div>","PeriodicalId":48757,"journal":{"name":"Astronomy and Computing","volume":"49 ","pages":"Article 100885"},"PeriodicalIF":1.9,"publicationDate":"2024-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142420005","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Magritte, a modern software library for spectral line radiative transfer","authors":"T. Ceulemans ,&nbsp;F. De Ceuster ,&nbsp;L. Decin ,&nbsp;J. Yates","doi":"10.1016/j.ascom.2024.100889","DOIUrl":"10.1016/j.ascom.2024.100889","url":null,"abstract":"<div><div>Spectral line observations are an indispensable tool to remotely probe the physical and chemical conditions throughout the universe. Modelling their behaviour is a computational challenge that requires dedicated software. In this paper, we present the first long-term stable release of <span>Magritte</span>, an open-source software library for line radiative transfer. First, we establish its necessity with two applications. Then, we introduce the overall design strategy and the application/programmer interface (API). Finally, we present three key improvements over previous versions: (1) an improved re-meshing algorithm to efficiently coarsen the spatial discretisation of a model; (2) a variation on Ng-acceleration, a popular acceleration-of-convergence method for non-LTE line transfer; and, (3) a semi-analytic approximation for line optical depths in the presence of large velocity gradients.</div></div>","PeriodicalId":48757,"journal":{"name":"Astronomy and Computing","volume":"49 ","pages":"Article 100889"},"PeriodicalIF":1.9,"publicationDate":"2024-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142593528","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Photometric redshifts probability density estimation from recurrent neural networks in the DECam local volume exploration survey data release 2","authors":"G. Teixeira ,&nbsp;C.R. Bom ,&nbsp;L. Santana-Silva ,&nbsp;B.M.O. Fraga ,&nbsp;P. Darc ,&nbsp;R. Teixeira ,&nbsp;J.F. Wu ,&nbsp;P.S. Ferguson ,&nbsp;C.E. Martínez-Vázquez ,&nbsp;A.H. Riley ,&nbsp;A. Drlica-Wagner ,&nbsp;Y. Choi ,&nbsp;B. Mutlu-Pakdil ,&nbsp;A.B. Pace ,&nbsp;J.D. Sakowska ,&nbsp;G.S. Stringfellow","doi":"10.1016/j.ascom.2024.100886","DOIUrl":"10.1016/j.ascom.2024.100886","url":null,"abstract":"<div><div>Photometric wide-field surveys are imaging the sky in unprecedented detail. These surveys face a significant challenge in efficiently estimating galactic photometric redshifts while accurately quantifying associated uncertainties. In this work, we address this challenge by exploring the estimation of Probability Density Functions (PDFs) for the photometric redshifts of galaxies across a vast area of 17,000 square degrees, encompassing objects with a median 5<span><math><mi>σ</mi></math></span> point-source depth of <span><math><mi>g</mi></math></span> <span><math><mo>=</mo></math></span> 24.3, <span><math><mrow><mi>r</mi><mo>=</mo><mn>23</mn><mo>.</mo><mn>9</mn></mrow></math></span>, <span><math><mi>i</mi></math></span> <span><math><mo>=</mo></math></span> 23.5, and <span><math><mi>z</mi></math></span> <span><math><mo>=</mo></math></span> 22.8 mag. Our approach uses deep learning, specifically integrating a Recurrent Neural Network architecture with a Mixture Density Network, to leverage magnitudes and colors as input features for constructing photometric redshift PDFs across the whole DECam Local Volume Exploration (DELVE) survey sky footprint. Subsequently, we rigorously evaluate the reliability and robustness of our estimation methodology, gauging its performance against other well-established machine learning methods to ensure the quality of our redshift estimations. Our best results constrain photometric redshifts with the bias of <span><math><mrow><mo>−</mo><mn>0</mn><mo>.</mo><mn>0013</mn></mrow></math></span>, a scatter of 0.0293, and an outlier fraction of 5.1%. These point estimates are accompanied by well-calibrated PDFs evaluated using diagnostic tools such as Probability Integral Transform and Odds distribution. We also address the problem of the accessibility of PDFs in terms of disk space storage and the time demand required to generate their corresponding parameters.We present a novel Autoencoder model that reduces the size of PDF parameter arrays to one-sixth of their original length, significantly decreasing the time required for PDF generation to one-eighth of the time needed when generating PDFs directly from the magnitudes.</div></div>","PeriodicalId":48757,"journal":{"name":"Astronomy and Computing","volume":"49 ","pages":"Article 100886"},"PeriodicalIF":1.9,"publicationDate":"2024-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142420004","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Accelerating universe in f(R,Lm) gravity","authors":"A. Beesham ,&nbsp;R.K. Tiwari ,&nbsp;B.K. Shukla ,&nbsp;D. Sofuoğlu ,&nbsp;A. Tiwari","doi":"10.1016/j.ascom.2024.100888","DOIUrl":"10.1016/j.ascom.2024.100888","url":null,"abstract":"<div><div>This paper investigates the dynamics of cosmic expansion within the framework of <span><math><mrow><mi>f</mi><mrow><mo>(</mo><mi>R</mi><mo>,</mo><msub><mrow><mi>L</mi></mrow><mrow><mi>m</mi></mrow></msub><mo>)</mo></mrow></mrow></math></span> gravity, focusing on the late-time behavior of the universe modeled as a flat Friedmann–Lemaître–Robertson–Walker spacetime. We derive an analytical solution for the field equations and employ advanced statistical techniques, including the Markov Chain Monte Carlo (MCMC) method, to determine best-fit values for the key cosmological parameters, such as the Hubble parameter and the deceleration parameter. Our findings reveal a transition from a decelerating to an accelerating phase of cosmic expansion, aligning closely with observational data as in the <span><math><mi>Λ</mi></math></span>CDM model. The analysis of energy conditions indicates that the strong energy condition is violated, in keeping with the current accelerated expansion of the universe and the nature of dark energy. By elucidating the quintessence behavior of our model through statefinder and Om diagnostics, this study contributes to a deeper understanding of cosmic evolution and the fundamental forces at play. The insights gained pave the way for future research into alternative cosmological models, inviting further exploration of the mysteries surrounding dark energy and the ultimate fate of the universe.</div></div>","PeriodicalId":48757,"journal":{"name":"Astronomy and Computing","volume":"49 ","pages":"Article 100888"},"PeriodicalIF":1.9,"publicationDate":"2024-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142571258","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"An efficient approach for searching three-body periodic orbits passing through Eulerian configuration","authors":"I. Hristov,&nbsp;R. Hristova","doi":"10.1016/j.ascom.2024.100880","DOIUrl":"10.1016/j.ascom.2024.100880","url":null,"abstract":"<div><div>A new efficient approach for searching three-body periodic equal-mass collisionless orbits passing through Eulerian configuration is presented. The approach is based on a symmetry property of the solutions at the half period. Depending on two previously established symmetry types on the shape sphere, each solution is presented by one or two distinct initial conditions (one or two points in the search domain). A numerical search based on Newton’s method on a relatively coarse search grid for solutions with relatively small scale-invariant periods <span><math><mrow><msup><mrow><mi>T</mi></mrow><mrow><mo>∗</mo></mrow></msup><mo>&lt;</mo><mn>70</mn></mrow></math></span> is conducted. The linear systems at each Newton’s iteration are computed by high order high precision Taylor series method. The search produced 12,431 initial conditions (i.c.s) corresponding to 6333 distinct solutions. In addition to passing through the Eulerian configuration, 35 of the solutions are also free-fall ones. Although most of the found solutions are new, all linearly stable solutions among them (only 7) are old ones. Particular attention is paid to the details of the high precision computations and the analysis of accuracy. All i.c.s are given with 100 correct digits.</div></div>","PeriodicalId":48757,"journal":{"name":"Astronomy and Computing","volume":"49 ","pages":"Article 100880"},"PeriodicalIF":1.9,"publicationDate":"2024-09-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S2213133724000957/pdfft?md5=e0e9ef0e698ea1e1adc33a7e5eff7275&pid=1-s2.0-S2213133724000957-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142315442","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Formation of S2 species in different redox states by radiative association in atomic and ionic collisions","authors":"Lidan Xiao ,&nbsp;Yang Chen ,&nbsp;Di Liu ,&nbsp;Boris F. Minaev ,&nbsp;Bing Yan","doi":"10.1016/j.ascom.2024.100877","DOIUrl":"10.1016/j.ascom.2024.100877","url":null,"abstract":"<div><div>Radiative associations for formations of the S₂, S₂⁺ and S₂^- molecular species during atomic collisions S(³P_u) + S(³P_u), S(³P_u) + S⁺(⁴S_u) and S(³P_u) + S^-(²P_u) are investigated. The adiabatic potential energy curves (PECs) and spin-allowed transition dipole moments (TDMs) are obtained by the internally contracted multireference configuration interaction method with the Davidson correction (icMRCI+Q). A number of PECs and TDMs are chosen to calculate the corresponding cross-sections and rate coefficients of radiative associations. The calculated rate coefficients are valid for the temperatures from 100 to 16000 K and fitted to the analytical function according to the three-parameter Arrhenius–Kooij formula. These results indicate that transitions originating in the ΔΛ=0 selection rule are the main contributors for the radiative association process. The present study can elucidate the further understanding the radiative association, which plays an important role in the formation and evolution of the S₂, S₂⁺ and S₂^- molecules.</div></div>","PeriodicalId":48757,"journal":{"name":"Astronomy and Computing","volume":"49 ","pages":"Article 100877"},"PeriodicalIF":1.9,"publicationDate":"2024-09-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142312426","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Determining research priorities using machine learning","authors":"B.A. Thomas ,&nbsp;A. Buonomo ,&nbsp;H. Thronson ,&nbsp;L. Barbier","doi":"10.1016/j.ascom.2024.100879","DOIUrl":"10.1016/j.ascom.2024.100879","url":null,"abstract":"<div><p>We summarize our exploratory investigation into whether Machine Learning (ML) techniques applied to publicly available professional text can substantially augment strategic planning for astronomy. We find that an approach based on Latent Dirichlet Allocation (LDA) using content drawn from astronomy journal papers can be used to infer high-priority research areas. While the LDA models are challenging to interpret, we find that they may be strongly associated with meaningful keywords and scientific papers which allow for human interpretation of the topic models.</p><p>Significant correlation is found between the results of applying these models to the previous decade of astronomical research (“1998–2010” corpus) and the contents of the Science Frontier Panels report which contains high-priority research areas identified by the 2010 National Academies’ Astronomy and Astrophysics Decadal Survey (“DS2010” corpus). Significant correlations also exist between model results of the 1998–2010 corpus and the submitted whitepapers to the Decadal Survey (“whitepapers” corpus). Importantly, we derive predictive metrics based on these results which can provide leading indicators of which content modeled by the topic models will become highly cited in the future. Using these identified metrics and the associations between papers and topic models it is possible to identify important papers for planners to consider.</p><p>A preliminary version of our work was presented by Thronson et al. (2021) and Thomas et al. (2022).</p></div>","PeriodicalId":48757,"journal":{"name":"Astronomy and Computing","volume":"49 ","pages":"Article 100879"},"PeriodicalIF":1.9,"publicationDate":"2024-09-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142167343","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}