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Joint analyses of the large-scale distribution of galaxies, and their motions under the gravitational influence of this density field, allow powerful tests of the cosmological model, including measurement of the growth rate of cosmic…

Cosmology and Nongalactic Astrophysics · Physics 2024-10-14 Chris Blake , Ryan J. Turner

Analyses of peculiar velocity surveys face several challenges, including low signal--to--noise in individual velocity measurements and the presence of small--scale, nonlinear flows. This is the second in a series of papers in which we…

Astrophysics · Physics 2009-11-07 Hume A. Feldman , Richard Watkins , Adrian L. Melott , Scott W. Chambers

The complex relationship between the galaxy density field and the underlying matter field limits our ability to extract cosmological constraints from galaxy redshift surveys. Our approach is to use halos rather than galaxies to trace the…

Astrophysics · Physics 2009-08-12 Beth A. Reid , David N. Spergel , Paul Bode

Modeling of the spectral line energy distribution (SLED) of the CO molecule can reveal the physical conditions (temperature, density) of molecular gas in Galactic clouds and other galaxies. Recently, the Herschel Space Observatory and ALMA…

Astrophysics of Galaxies · Physics 2018-05-23 J. Kamenetzky , G. C. Privon , D. Narayanan

We describe application of the `shapelet' linear decomposition of galaxy images to morphological classification using images of $\sim$ 3000 galaxies from the Sloan Digital Sky Survey. After decomposing the galaxies we perform a principal…

Astrophysics · Physics 2009-11-10 Brandon C. Kelly , Timothy A. McKay

We derive constraints on cosmological parameters using the power spectrum of galaxy clustering measured from the final two-degree field galaxy redshift survey (2dFGRS) and a compilation of measurements of the temperature power spectrum and…

Here, we present a machine vision approach, combining a VAE framework with PCA, to decipher galaxy images. Using mock gri-band images from the EAGLE simulation, the VAE finds that around 35 features are needed to describe the images. Adding…

Astrophysics of Galaxies · Physics 2025-11-27 Samuel Howie , Ting-Yun Cheng , Carlton M. Baugh

We analyze the photometric information contained in individual pixels of galaxies in the Hubble Deep Field North (HDFN) using a new technique, _pixel-z_, that combines predictions of evolutionary synthesis models with photometric redshift…

We use the number density of peaks in the smoothed cosmological density field taken from the 2dF Galaxy Redshift Survey to constrain parameters related to the power spectrum of mass fluctuations, n (the spectral index), dn/d(lnk) (rolling…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-14 S. De , R. A. C. Croft

In the era of vast spectroscopic surveys focusing on Galactic stellar populations, astronomers want to exploit the large quantity and good quality of data to derive their atmospheric parameters without losing precision from automatic…

Solar and Stellar Astrophysics · Physics 2017-12-13 M. Tsantaki , D. T. Andreasen , G. D. C. Teixeira , S. G. Sousa , N. C. Santos , E. Delgado-Mena , G. Bruzual

The morphology of a galaxy has been shown to encode the evolutionary history and correlates strongly with physical properties such as stellar mass, star formation rates and past merger events. While the majority of galaxies in the local…

Astrophysics of Galaxies · Physics 2023-02-23 Clár-Bríd Tohill , Steven Bamford , Christopher Conselice

We present a power spectrum analysis of the final 2dF Galaxy Redshift Survey, employing a direct Fourier method. The sample used comprises 221,414 galaxies with measured redshifts. We investigate in detail the modelling of the sample…

We present a comprehensive study of the applications of the pixel color-magnitude diagram (pCMD) technique for measuring star formation histories (SFHs) and other stellar population parameters of galaxies, and demonstrate that the technique…

Astrophysics of Galaxies · Physics 2019-05-15 B. A. Cook , Charlie Conroy , Pieter van Dokkum , Joshua S. Speagle

Large direct-imaging surveys usually use a template-fitting technique to estimate photometric redshifts for galaxies, which are then applied to derive important galaxy properties such as luminosities and stellar masses. These estimates can…

Astrophysics of Galaxies · Physics 2015-06-22 B. C. Hsieh , H. K. C. Yee

We make use of snapshots taken from the Quijote suite of simulations, consisting of 2000 simulations where five cosmological parameters have been varied ($\Omega_m$, $\Omega_b$, $h$, $n_s$ and $\sigma_8$) in order to investigate the…

Cosmology and Nongalactic Astrophysics · Physics 2021-10-12 Andrei Lazanu

Measuring distances of cosmological sources such as galaxies, stars and quasars plays an increasingly critical role in modern cosmology. Obtaining the optical spectrum and consequently calculating the redshift as a distance indicator could…

Astrophysics of Galaxies · Physics 2022-01-13 Aidin Momtaz , Mohammad Hossein Salimi , Soroush Shakeri

Temporal and spectral information extracted from a stream of photons received from astronomical sources is the foundation on which we build understanding of various objects and processes in the Universe. Typically astronomers fit a number…

High Energy Astrophysical Phenomena · Physics 2016-11-18 T. N. Ukwatta , P. R. Wozniak

Two parameters are developed to analyze the CCD images from ground-based and/or space telescopes. The first parameter, deduced from the intensity profile of the object sharp, is useful to resolve stars and hot pixels. The second parameter…

Astrophysics · Physics 2007-05-23 Filip Hroch

We compare the properties of clouds in simulated M33 galaxies to those observed in the real M33. We apply a friends of friends algorithm and CPROPS to identify clouds, as well as a pixel by pixel analysis. We obtain very good agreement…

Astrophysics of Galaxies · Physics 2019-03-20 C. L. Dobbs , E. Rosolowsky , A. R. Pettitt , J. Braine , E. Corbelli , J. Sun