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Molecular clouds form from the atomic phase of the interstellar medium. However, characterizing the transition between the atomic and the molecular interstellar medium (ISM) is a difficult observational task. Here we address cloud formation…

Angular power spectra are an important measure of the angular clustering of a given distribution. In Cosmology, they are applied to such vastly different observations as galaxy surveys that cover a fraction of the sky and the Cosmic…

Astrophysics · Physics 2007-11-15 Brett Hayes , Robert Brunner , Volodymyr Kindratenko

Principal component analysis (PCA) is a widespread technique for data analysis that relies on the covariance-correlation matrix of the analyzed data. However to properly work with high-dimensional data, PCA poses severe mathematical…

Quantitative Methods · Quantitative Biology 2018-10-18 Luigi Leonardo Palese

Turbulence plays a major role in the formation and evolution of molecular clouds. The problem is that turbulent velocities are convolved with the density of an observed region. To correct for this convolution, we investigate the relation…

Astrophysics of Galaxies · Physics 2015-05-28 Julia Roman-Duval , Christoph Federrath , Christopher Brunt , Mark Heyer , James Jackson , Ralf Klessen

Given the rapid development of 3D scanners, point clouds are becoming popular in AI-driven machines. However, point cloud data is inherently sparse and irregular, causing significant difficulties for machine perception. In this work, we…

Computer Vision and Pattern Recognition · Computer Science 2022-10-04 Shi Qiu , Saeed Anwar , Nick Barnes

Cluster strong lensing cosmography is a promising probe of the background geometry of the Universe and several studies have emerged, thanks to the increased quality of observations using space and ground-based telescopes. For the first…

Cosmology and Nongalactic Astrophysics · Physics 2022-01-19 G. B. Caminha , S. H. Suyu , C. Grillo , P. Rosati

The heating of the Sun's chromosphere remains poorly understood. While progress has been made on understanding what drives the quiet Sun internetwork chromosphere, chromospheric heating in strong magnetic field regions continues to present…

Solar and Stellar Astrophysics · Physics 2013-02-07 J. de la Cruz Rodríguez , B. De Pontieu , M. Carlsson , L. H. M. Rouppe van der Voort

We propose an empirical method for identifying low damped modes and corresponding mode shapes using frequency measurements from a Wide Area Monitoring System. The method consists of two main steps: Firstly, Complex Principal Component…

Signal Processing · Electrical Eng. & Systems 2021-02-02 Hallvar Haugdal , Kjetil Uhlen

The solar chromosphere is a vigorously dynamic region of the sun, where waves and magnetic fields play an important role. To improve chromospheric diagnostics, we present new observations in Ca II 8542 carried out with the SST/CRISP on La…

Solar and Stellar Astrophysics · Physics 2015-03-14 Jaime de la Cruz Rodríguez , Hector Socas-Navarro , Michiel van Noort , Luc Rouppe van der Voort

For many transitions, atomic data, such as the oscillator strength (log(gf)) and the central wavelength of the line, are poorly constrained or even unknown. We present and test a new inversion method that infers atomic line parameters and…

Solar and Stellar Astrophysics · Physics 2024-06-19 D. Vukadinović , H. N. Smitha , A. Korpi-Lagg , M. van Noort , J. S. Castellanos Durán , S. K. Solanki

Present-day semi-empirical models of solar irradiance (SI) variations employ spectra computed on one-dimensional atmosphere models (1D models) representative of various solar surface features to reconstruct SI changes measured on timescales…

Solar and Stellar Astrophysics · Physics 2017-06-14 A. Cristaldi , I. Ermolli

We wish to relate the degree scale structure of galactic diffuse clouds to sub-arcsecond atomic and molecular absorption spectra obtained against extragalactic continuum background sources. To do this, we used the ARO 12m telescope to map…

Astrophysics of Galaxies · Physics 2015-06-04 H. S. Liszt , J. Pety

To mitigate the severe information loss arising from widely adopted linear scale cuts in constraints on modified gravity parameterisations with Weak Lensing (WL) and Large-Scale Structure (LSS) data, we introduce a novel alternative method…

Cosmology and Nongalactic Astrophysics · Physics 2026-03-10 C. M. A. Zanoletti , C. D. Leonard

We investigate the linear correlation coefficient between the intensities at different wavelengths in photospheric and chromospheric spectral lines. Waves that propagate vertically through the stratified solar atmosphere affect different…

Solar and Stellar Astrophysics · Physics 2015-05-14 C. Beck , W. Rammacher

During a solar flare, it is believed that reconnection takes place in the corona followed by fast energy transport to the chromosphere. The resulting intense heating strongly disturbs the chromospheric structure, and induces complex…

Solar and Stellar Astrophysics · Physics 2019-04-30 Christopher M. J. Osborne , John A. Armstrong , Lyndsay Fletcher

Principal component analysis (PCA) is a dimensionality reduction method in data analysis that involves diagonalizing the covariance matrix of the dataset. Recently, quantum algorithms have been formulated for PCA based on diagonalizing a…

Quantum Physics · Physics 2022-10-26 Max Hunter Gordon , M. Cerezo , Lukasz Cincio , Patrick J. Coles

We have developed a web tool to perform Principal Component Analysis (PCA, Murtagh & Heck 1987; Kendall 1980) onto spectral data. The method is especially designed to perform spectral classification of galaxies from a sample of input…

Astrophysics of Galaxies · Physics 2009-09-22 Mauricio Ortiz , Gaspar Galaz

The principal component analysis (PCA), a mathematical tool commonly used in statistics, has recently been employed to interpret the $p_T$-dependent fluctuations of harmonic flow $v_n$ in terms of leading and subleading flow modes in heavy…

Nuclear Experiment · Physics 2020-08-26 Ziming Liu , Arabinda Behera , Huichao Song , Jiangyong Jia

We study chromospheric oscillations including umbral flashes and running penumbral waves in a sunspot of active region (AR) using scanning spectroscopy in H-alpha and Ca II 8542A, with the Fast Imaging Solar Spectrograph (FISS) at the 1.6…

Solar and Stellar Astrophysics · Physics 2013-02-07 Ram Ajor Maurya , Jongchul Chae , Hyungmin Park , Heesu Yang , Donguk Song , Kyuhyoun Cho

Filaments are omnipresent features in the solar atmosphere. Their location, properties and time evolution can provide information about changes in solar activity and assist the operational space weather forecast. Therefore, filaments have…

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