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The intrinsic alignment of galaxies is a key factor in modeling weak-lensing observations and can serve as a valuable signal for both cosmological and astrophysical studies. Modelling this signal requires understanding how galaxy shapes…

Cosmology and Nongalactic Astrophysics · Physics 2025-07-16 Francisco Maion , Jens Stücker , Raul E. Angulo

We study the optical morphology of galaxies in a large-scale hydrodynamic cosmological simulation, the EAGLE simulation. Galaxy morphologies were characterized using non-parametric statistics (Gini, $M_{20}$, Concentration and Asymmetry)…

Astrophysics of Galaxies · Physics 2020-01-08 Lucas A. Bignone , Susana E. Pedrosa , James W. Trayford , Patricia B. Tissera , Leonardo J. Pellizza

Galaxy morphology in stellar light can be described by a series of "non-parametric" or "morphometric" parameters, such as concentration-asymmetry-smoothness, Gini, $M_{20}$, and Sersic fit. These parameters can be applied to column density…

We test the isotropy of the local distribution of galaxies using the 2MASS extended source catalogue. By decomposing the full sky survey into distinct patches and using a combination of photometric and spectroscopic redshift data, we use…

Cosmology and Nongalactic Astrophysics · Physics 2014-10-29 Stephen Appleby , Arman Shafieloo

Non-parametric morphology statistics have been used for decades to classify galaxies into morphological types and identify mergers in an automated way. In this work, we assess how reliably we can identify galaxy post-mergers with…

Quantitative dynamical models of galaxies require deprojecting the observed surface brightness to determine the luminosity density of the galaxy. Existing deprojection methods for axisymmetric galaxies assume that a unique deprojection…

Astrophysics · Physics 2015-06-24 Aaron J. Romanowsky , Christopher S. Kochanek

Accurate measurement of galaxy structures is a prerequisite for quantitative investigation of galaxy properties or evolution. Yet, the impact of galaxy inclination and dust on commonly used metrics of galaxy structure is poorly quantified.…

Astrophysics of Galaxies · Physics 2017-03-23 Brian Devour , Eric Bell

The systematic mapping of obscured and optically invisible galaxies behind the Milky Way through complementary surveys are important in arriving at the whole-sky distribution of complete galaxy samples and therewith for our understanding of…

Astrophysics · Physics 2007-05-23 R. C. Kraan-Korteweg

Gravitational lensing shear has the potential to be the most powerful tool for constraining the nature of dark energy. However, accurate measurement of galaxy shear is crucial and has been shown to be non-trivial by the Shear TEsting…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-13 L. M. Voigt , S. L. Bridle

We present an analysis of asymmetries in global HI spectra from the extended GALEX Arecibo SDSS Survey (xGASS), a stellar mass-selected and gas fraction-limited survey which is representative of the HI properties of galaxies in the local…

Astrophysics of Galaxies · Physics 2020-01-22 Adam B. Watts , Barbara Catinella , Luca Cortese , Chris Power

We discuss the possibility of performing blind surveys to detect large-scale features of the universe using 21cm emission. Using instruments with approx. 5'-10' resolution currently in the planning stage, it should be possible to detect…

Astrophysics · Physics 2008-11-26 Richard A. Battye , Rod D. Davies , Jochen Weller

We present an analysis of the sky distribution of neutral hydrogen (HI) deficiency and spectral asymmetry for galaxies detected by the HI Parkes All-Sky Survey (HIPASS) as a function of projected environment density. Previous studies of…

Astrophysics of Galaxies · Physics 2020-10-21 T. N. Reynolds , T. Westmeier , L. Staveley-Smith

Many physical properties of galaxies correlate with one another, and these correlations are often used to constrain galaxy formation models. Such correlations include the color-magnitude relation, the luminosity-size relation, the…

Astrophysics · Physics 2009-11-13 Graziano Rossi , Ravi K. Sheth

The intrinsic scatter in the ellipticities of galaxies about the mean shape, known as "shape noise," is the most important source of noise in weak lensing shear measurements. Several approaches to reducing shape noise have recently been put…

Cosmology and Nongalactic Astrophysics · Physics 2015-09-21 Rupert A. C. Croft , Peter E. Freeman , Thomas S. Schuster , Chad M. Schafer

We describe an efficient algorithm for calculating the statistics of weak lensing by large-scale structure based on a tiled set of independent particle-mesh N-body simulations which telescope in resolution along the line of sight. This…

Astrophysics · Physics 2008-11-26 Martin White , Wayne Hu

We present an analysis of morphological, kinematic and spectral asymmetries in observations of atomic neutral hydrogen (HI) gas from the Local Volume HI Survey (LVHIS), the VLA Imaging of Virgo in Atomic Gas (VIVA) survey and the Hydrogen…

Astrophysics of Galaxies · Physics 2020-03-11 T. N. Reynolds , T. Westmeier , L. Staveley-Smith , G. Chauhan , C. D. P. Lagos

Redshift is a key quantity for inferring cosmological model parameters. In photometric redshift estimation, cosmologists use the coarse data collected from the vast majority of galaxies to predict the redshift of individual galaxies. To…

Applications · Statistics 2016-04-07 Rafael Izbicki , Ann B. Lee , Peter E. Freeman

We demonstrate that morphological observables (e.g. steepness of the radial light profile, ellipticity, asymmetry) are intertwined and cannot be measured independently of each other. We present strong arguments in favour of model-based…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-19 Rene Andrae , Knud Jahnke , Peter Melchior

Modern spectroscopic surveys can only target a small fraction of the vast amount of photometrically cataloged sources in wide-field surveys. Here, we report the development of a generative AI method capable of predicting optical galaxy…

Soon to be operational HI survey instruments such as APERTIF and ASKAP will produce large datasets. These surveys will provide information about the HI in and around hundreds of galaxies with a typical signal-to-noise ratio of $\sim$ 10 in…

Instrumentation and Methods for Astrophysics · Physics 2016-09-14 D. Punzo , J. M. van der Hulst , J. B. T. M. Roerdink