Astronomy and Computing最新文献

{"title":"A general relativistic hydrodynamic simulation code for studying advective, sub-Keplerian accretion flow onto black holes","authors":"S.K. Garain","doi":"10.1016/j.ascom.2025.100974","DOIUrl":"10.1016/j.ascom.2025.100974","url":null,"abstract":"<div><div>In this paper, we describe a general relativistic hydrodynamics simulation code which is developed to simulate advective accretion flow onto black holes. We are particularly interested in the accretion simulations of sub-Keplerian matter in the close vicinity of black holes. Due to the presence of centrifugal barrier, a nearly free-falling sub-Keplerian accretion flow slows down close to a black hole and can even pass through shocks before accelerating again to the black hole. We design our simulation code using the high resolution shock capturing scheme so that such shock structures can be captured and analyzed for relevance. In this paper, we describe our implementation and validation of the code against a few known analytical and numerical results of sub-Keplerian matter accretion.</div></div>","PeriodicalId":48757,"journal":{"name":"Astronomy and Computing","volume":"53 ","pages":"Article 100974"},"PeriodicalIF":1.9,"publicationDate":"2025-06-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144297827","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":"Impact of cosmic web on galaxy properties and their correlations: Insights from Principal Component Analysis","authors":"Anindita Nandi,&nbsp;Biswajit Pandey","doi":"10.1016/j.ascom.2025.100972","DOIUrl":"10.1016/j.ascom.2025.100972","url":null,"abstract":"<div><div>We use Principal Component Analysis (PCA) to analyse a volume-limited sample from the SDSS and explore how cosmic web environments affect the interrelations between various galaxy properties, such as <span><math><mrow><mo>(</mo><mi>u</mi><mo>−</mo><mi>r</mi><mo>)</mo></mrow></math></span> colour, stellar mass, specific star formation rate, metallicity, morphology, and <span><math><mrow><mi>D</mi><mn>4000</mn></mrow></math></span>. Our analysis reveals that the first three principal components (PC1, PC2 and PC3) account for approximately <span><math><mrow><mo>∼</mo><mn>85</mn><mtext>%</mtext></mrow></math></span> of the data variance. We classify galaxies into different cosmic web environments based on the eigenvalues of the deformation tensor and compare PC1, PC2, PC3 across these environments, ensuring a mass-matched sample of equal size for each environment. PC1 is dominated by colour, sSFR, D4000, and morphology. It displays clear bimodality across all cosmic web environments, with sheets and clusters showing distinct preferences for negative and positive PC1 values, respectively. This variation reflects the strong role of environmental processes in regulating star formation. PC2 and PC3, respectively show positively and negatively skewed unimodal distributions in all environments. PC2 is primarily influenced by metallicity whereas PC3 is dominated by stellar mass. It indicates that metallicity evolves gradually and is less sensitive to environmental extremes, highlighting the importance of internal, secular processes. PC3 likely captures residual variation in stellar mass within the two main galaxy populations (star-forming and quiescent) separated by PC1. A Kolmogorov–Smirnov (KS) test confirms that the distributions of PC1, PC2 and PC3 differ significantly across environments, with a confidence level exceeding 99.99%. Furthermore, we calculate the normalized mutual information (NMI) between the principal components and individual galaxy properties within different cosmic web environments. A two-tailed t-test reveals that for each relationship and each pair of environments, the null hypothesis is rejected with a confidence level <span><math><mrow><mo>&gt;</mo><mn>99</mn><mo>.</mo><mn>99</mn><mtext>%</mtext></mrow></math></span>. Our analysis confirms that cosmic web environments play a significant role in shaping the correlations between galaxy properties.</div></div>","PeriodicalId":48757,"journal":{"name":"Astronomy and Computing","volume":"53 ","pages":"Article 100972"},"PeriodicalIF":1.9,"publicationDate":"2025-06-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144313613","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":"Geometric analysis of variability of radiocarbon abundances and solar activity","authors":"Isao Shoji ,&nbsp;Tadafumi Takata ,&nbsp;Yoshihiko Mizumoto","doi":"10.1016/j.ascom.2025.100971","DOIUrl":"10.1016/j.ascom.2025.100971","url":null,"abstract":"<div><div>This paper discusses a geometric time series analysis of variability of radiocarbon abundances and solar activity. Cosmic rays sometimes have a severe impact on the Earth’s environment. They interact with atoms in the atmosphere, producing radionuclides such as radiocarbon. Consequently, the ratio of radiocarbon to stable carbon in the atmosphere fluctuates on the basis of the influx of cosmic rays. Consequently, historical records of radiocarbon abundances show the intensity of cosmic rays in the past. The International Calibration (IntCal) curve widely used for radiocarbon dating is also used as a reference for such records. From a statistical point of view, detecting rapid changes in radiocarbon abundances, which are considered indicators of intense cosmic rays, from the IntCal data is challenging because such variations are generally smoothed out during the calibration process. However, in this study, we used a geometric time series analysis method to identify several rapid changes directly from the IntCal data. These variations in radiocarbon abundances also serve as indicators of solar activity. We also detected signals corresponding to solar grand minima and grand maxima by correlating them with temporal changes in the vector field derived from the dynamical system characterized by a second-order random oscillation.</div></div>","PeriodicalId":48757,"journal":{"name":"Astronomy and Computing","volume":"53 ","pages":"Article 100971"},"PeriodicalIF":1.9,"publicationDate":"2025-06-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144313610","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":"Energy and polarization based online interference mitigation in radio interferometry","authors":"S. Yatawatta,&nbsp;A.-J. Boonstra,&nbsp;C.P. Broekema","doi":"10.1016/j.ascom.2025.100973","DOIUrl":"10.1016/j.ascom.2025.100973","url":null,"abstract":"<div><div>Radio frequency interference (RFI) is a persistent contaminant in terrestrial radio astronomy. While new radio interferometers are becoming operational, novel sources of RFI are also emerging. In order to strengthen the mitigation of RFI in modern radio interferometers, we propose an online RFI mitigation scheme that can be run in the correlator of such interferometers. We combine statistics based on the energy as well as the polarization alignment of the correlated signal to develop an online RFI mitigation scheme that can be applied to a data stream produced by the correlator in real-time, especially targeted at low duty-cycle or transient RFI detection. In order to improve the computational efficiency, we explore the use of both single precision and half precision floating point operations in implementing the RFI mitigation algorithm. This ideally suits its deployment in accelerator computing devices such as graphics processing units (GPUs) as used by the LOFAR correlator. We provide results based on simulations and real data to demonstrate the efficacy of the proposed method.</div></div>","PeriodicalId":48757,"journal":{"name":"Astronomy and Computing","volume":"53 ","pages":"Article 100973"},"PeriodicalIF":1.9,"publicationDate":"2025-06-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144289191","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":"AutoKnots: Adaptive knot allocation for spline interpolation","authors":"Sandro D.P. Vitenti ,&nbsp;Fernando de Simoni ,&nbsp;Mariana Penna-Lima ,&nbsp;Eduardo J. Barroso","doi":"10.1016/j.ascom.2025.100970","DOIUrl":"10.1016/j.ascom.2025.100970","url":null,"abstract":"<div><div>In astrophysical and cosmological analyses, the increasing quality and volume of astronomical data demand efficient and precise computational tools. Interpolation methods, particularly spline-based approaches, play a critical role in this context. This work introduces a novel adaptive algorithm for automatic knots (AutoKnots) allocation in spline interpolation, designed to meet user-defined precision requirements. Unlike traditional methods relying on manually configured knot distributions, the proposed technique automatically determines the optimal number and placement of knots based on interpolation error criteria, often requiring only a single parameter. The algorithm progressively improves interpolation by adaptively sampling the function-to-be-approximated, <span><math><mrow><mi>f</mi><mrow><mo>(</mo><mi>x</mi><mo>)</mo></mrow></mrow></math></span>, in regions where the interpolation error exceeds the desired threshold. All function evaluations contribute to the final approximation, ensuring efficiency. Although each resampling step involves recomputing the interpolation table, this process is highly optimized and computationally negligible compared to the cost of evaluating <span><math><mrow><mi>f</mi><mrow><mo>(</mo><mi>x</mi><mo>)</mo></mrow></mrow></math></span>. For inherently fast functions, interpolation may not offer significant benefits. Precision tests on different functions demonstrate the algorithm’s efficacy, while a heuristic enhancement improves accuracy in flat regions. Integrated into the Numerical Cosmology library (NumCosmo), this algorithm has been extensively used and tested. NumCosmo includes rigorous unit tests that underscore its robustness and reliability. As a practical application, we compute the surface mass density <span><math><mrow><mi>Σ</mi><mrow><mo>(</mo><mi>R</mi><mo>)</mo></mrow></mrow></math></span> and average surface mass density <span><math><mrow><mover><mrow><mi>Σ</mi></mrow><mo>¯</mo></mover><mrow><mo>(</mo><mo>&lt;</mo><mi>R</mi><mo>)</mo></mrow></mrow></math></span> for Navarro–Frenk–White and Hernquist halo density profiles, offering analytical benchmarks. This adaptive algorithm provides a mature, user-friendly tool for interpolation challenges in computational astrophysics and cosmology.</div></div>","PeriodicalId":48757,"journal":{"name":"Astronomy and Computing","volume":"53 ","pages":"Article 100970"},"PeriodicalIF":1.9,"publicationDate":"2025-06-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144254205","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":"SAS in ESA Datalabs: A new platform for XMM-Newton analysis","authors":"Esin G. Gülbahar ,&nbsp;Camille M. Diez ,&nbsp;Aitor Ibarra ,&nbsp;Ivan Valtchanov ,&nbsp;Richard Saxton ,&nbsp;Ignacio de la Calle Pérez ,&nbsp;Jose Lopez-Miralles ,&nbsp;Alejandro González Ganzábal ,&nbsp;Peter Kretschmar","doi":"10.1016/j.ascom.2025.100969","DOIUrl":"10.1016/j.ascom.2025.100969","url":null,"abstract":"<div><div>XMM-Newton is a cornerstone mission of the European Space Agency (ESA) for X-ray astronomy, providing high-quality X-ray data for astrophysical research since the start of the century. Its Science Analysis System (SAS) has been a reliable data reduction and analysis software, evolving throughout the years to meet changing user needs, while incorporating new methods. This paper presents the XMM-SAS Datalab, a tool within the cloud-based ESA Datalabs platform, designed to enhance the interactivity and collaborative potential of SAS. By integrating SAS with a modern, Python-based JupyterLab interface, it enables shared analysis workspaces, removes the need for local software setup, and provides faster access through containerised environments and preconfigured libraries. Moving SAS to the cloud preserves a consistent software setup while eliminating installation complexities, saving time and effort. A case study of the X-ray binary Vela X-1 demonstrates that the Datalabs platform reliably replicates local SAS outputs, with minimal deviations attributed to calibration file versions. The XMM-SAS Datalab allows straightforward X-ray data analysis with collaborative process, setting the way for future adaptations in e-science platforms and multi-wavelength astronomy, while offering traceability and reproducibility of scientific results.</div></div>","PeriodicalId":48757,"journal":{"name":"Astronomy and Computing","volume":"53 ","pages":"Article 100969"},"PeriodicalIF":1.9,"publicationDate":"2025-06-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144262710","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":"Cosmological implications and stability of f(Q,T) gravity with pilgrim dark energy model","authors":"M. Sharif ,&nbsp;Iqra Ibrar","doi":"10.1016/j.ascom.2025.100967","DOIUrl":"10.1016/j.ascom.2025.100967","url":null,"abstract":"<div><div>This manuscript endeavors to construct a pilgrim dark energy framework within the <span><math><mrow><mi>f</mi><mi>(Q,T)</mi></mrow></math></span> gravity theory, employing a correspondence approach aligned with a non-interacting model that incorporates pressureless matter alongside a power-law scale factor. Here <span><math><mi>Q</mi></math></span> and <span><math><mi>T</mi></math></span> represent the non-metricity and trace of the energy–momentum tensor, respectively. This extended modified gravity framework accurately replicates various epochs in the cosmological history. The <span><math><mrow><mi>f</mi><mi>(Q,T)</mi></mrow></math></span> gravity models are utilized to derive the equation of state parameter, phase planes and squared speed of sound. The analysis reveals that the reconstructed model exhibits an increasing or decreasing trend with the pilgrim dark energy parameter. The equation of state parameter characterizes the phantom regime, while the squared speed of sound parameter provides a stable framework for examining the ongoing cosmic evolution. The <span><math><mrow><msub><mrow><mi>ω</mi></mrow><mrow><mi>D</mi><mi>E</mi></mrow></msub><mo>−</mo><msubsup><mrow><mi>ω</mi></mrow><mrow><mi>D</mi><mi>E</mi></mrow><mrow><mo>′</mo></mrow></msubsup></mrow></math></span> plane trajectories reveal the freezing region, while the <span><math><mrow><mi>r</mi><mo>−</mo><mi>s</mi></mrow></math></span> phase plane shows the Chaplygin gas model. It is important to highlight that our findings align with the most recent observational data.</div></div>","PeriodicalId":48757,"journal":{"name":"Astronomy and Computing","volume":"53 ","pages":"Article 100967"},"PeriodicalIF":1.9,"publicationDate":"2025-05-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144212679","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":"SSOXmatch: A Java pipeline to compute cross-matches of Solar System bodies in astronomical observations","authors":"T. Alonso-Albi","doi":"10.1016/j.ascom.2025.100968","DOIUrl":"10.1016/j.ascom.2025.100968","url":null,"abstract":"<div><div>In this paper I will describe a new software package developed using the Java programming language, aimed to compute the positions of any Solar System body (among asteroids, comets, planets, and satellites) to help to perform cross-matches of them in observations taken from earth- and space-based observatories. The space telescopes supported are Hubble, James Webb, Euclid, XMM-Newton, Spitzer, Herschel, Gaia, Kepler, Chandra, and TESS, although the flexibility of the software allows to support any other mission without the need to change a single line of code. The orbital elements can be selected among the asteroid database from the Lowell observatory (completed with the cometpro database of comets maintained by the LTE), and the JPL database of minor bodies.</div><div>The software does not depend on external tools, and performs its own numerical integration of minor bodies. The dynamical model implemented for the Solar System includes the gravity effects of all major bodies, including the Earth, Moon, and Pluto as individual bodies, 16 perturbing asteroids as in other tools, the General Relativity effects, the oblateness of the Sun, Earth, and Moon, and the non-gravitational forces for both comets and asteroids. A complete set of web services allow to compute the cross-matches (that are later to be confirmed, for instance by visual inspection of the images) and also ephemerides of specific bodies. The code is highly optimized and follows the highest standards in terms of software quality and documentation.</div></div>","PeriodicalId":48757,"journal":{"name":"Astronomy and Computing","volume":"52 ","pages":"Article 100968"},"PeriodicalIF":1.9,"publicationDate":"2025-05-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143946499","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":"Analyzing the position and stability of the Lagrangian points under the gravitational effect of the Sun, Moon and the Earth including its oblateness","authors":"M. Kumar ,&nbsp;S. Yadav ,&nbsp;P.K. Behera","doi":"10.1016/j.ascom.2025.100966","DOIUrl":"10.1016/j.ascom.2025.100966","url":null,"abstract":"<div><div>The present study explores the existence and stability of the Lagrangian points in the Earth–Moon–Sun system, consider the artificial satellite moving around the Earth under the gravitational attraction of the Sun, the Earth and the Moon. Equations of motion of the satellite are determined in spherical polar coordinate system with the help of potential of the Earth. The positions and stability of the Lagrangian points lie on the <span><math><mi>x</mi></math></span>-axis and <span><math><mi>y</mi></math></span>-axis are investigated including the effect of <span><math><msub><mrow><mi>J</mi></mrow><mrow><mn>2</mn></mrow></msub></math></span> (oblateness of the Earth), <span><math><mi>ν</mi></math></span> (orbital angle of the Moon around the bary-center), <span><math><mi>α</mi></math></span> (orbital angle of the bary-center system around the Sun) and <span><math><mi>θ</mi></math></span> (longitude of the satellite). Finally, the zero velocity curves are drawn by taking different values of Jacobi constant. It is observed that region of possible motion decreases on increasing the values of Jacobi constants</div></div>","PeriodicalId":48757,"journal":{"name":"Astronomy and Computing","volume":"52 ","pages":"Article 100966"},"PeriodicalIF":1.9,"publicationDate":"2025-04-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143904146","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":"Classification of spiral galaxies by spiral arm number using convolutional neural network","authors":"Ming Wei Lee,&nbsp;John Y.H. Soo,&nbsp;Syarawi M.H. Sharoni","doi":"10.1016/j.ascom.2025.100965","DOIUrl":"10.1016/j.ascom.2025.100965","url":null,"abstract":"<div><div>The structural information of spiral galaxies such as the spiral arm number, offer valuable insights into the formation processes of spirals and their physical roles in galaxy evolution. We developed classifiers based on convolutional neural networks (CNNs) using variants of the EfficientNet architecture with different transfer learning techniques and pre-trained weights to categorise spiral galaxies by their number of spiral arms. A selected dataset from Galaxy Zoo 2, comprising 11<!--> <!-->718 images filtered based on appropriate criteria is used for training and evaluation. Both the V2M model (EfficientNetV2M architecture fine-tuned on ImageNet) and the B0 model (EfficientNetB0 architecture with Zoobot pre-trained weights) achieved high accuracy on the down-sampled dataset, with most performance metrics exceeding 0.8 across all classes, except for galaxies with 4 arms due to the limited number of samples in this category. Merging higher-arm-number classes (more than 4 arms) improved the V2M model’s accuracy significantly for 4-arm galaxies, as this approach allowed the model to focus on more distinct features within fewer, broader categories with a more balanced class distribution. GradCAM++ and SmoothGrad highlight the networks’ effectiveness in classifying galaxies, through the distinction of the galaxy structures and the extraction of the spiral arms, with the V2M model showing better capabilities in both tasks. Lower-arm galaxies tend to be misclassified as “can’t tell” when their spiral arms are not clearly visible, while higher-arm galaxies tend to be misclassified as having fewer arms when their features are only partially detected. The study also found that galaxies with 3 arms tend to have lower stellar masses, and this tendency is reduced in the model predictions. The models’ mispredictions between 2-arm and 1/3-arm are likely resulting from external interference and dynamic nature of spiral arms. The V2M model prediction also shows a slight tendency towards higher stellar mass in <strong>many-arm</strong> galaxies.</div></div>","PeriodicalId":48757,"journal":{"name":"Astronomy and Computing","volume":"52 ","pages":"Article 100965"},"PeriodicalIF":1.9,"publicationDate":"2025-04-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143869175","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}