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We have selected a sample of 88 nearby (z<0.1) galaxy clusters from the SDSS-DR4 with redshift information for the cluster members. We have derived global properties for each cluster, such as their mean recessional velocity, velocity…

Astrophysics · Physics 2019-08-19 J. A. L. Aguerri , R. Sanchez-Janssen , C. Munoz-Tunon

Bivariate luminosity functions (LFs) are computed for galaxies in the New York Value-Added Galaxy Catalogue, based on the Sloan Digital Sky Survey Data Release 4. The galaxy properties investigated are the morphological type, inverse…

Astrophysics · Physics 2009-11-11 Nicholas M Ball , Jon Loveday , Robert J Brunner , Ivan K Baldry , Jon Brinkmann

A common assumption is that galaxies fall in two distinct regions on a plot of specific star-formation rate (SSFR) versus galaxy stellar mass: a star-forming Galaxy Main Sequence (GMS) and a separate region of `passive' or `red and dead…

Astrophysics of Galaxies · Physics 2017-01-25 Stephen Eales , Pieter de Vis , Matthew Smith , Kiran Appah , Laure Ciesla , Chris Duffield , Simon Schofield

[Abridged] We assemble a sample of 45 intermediate X-ray luminosity galaxy clusters at low redshifts using SDSS data to conduct a comprehensive investigation into the photometric variation of red sequence modal galaxy colours with…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-03 Peter C. Jensen , Kevin A. Pimbblet

Aims: We present a new method that uses luminosity or stellar mass functions combined with clustering measurements to select samples of galaxies at different redshifts likely to follow a progenitor-to-descendant relationship. As the method…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-28 Nelson Padilla , Daniel Christlein , Eric Gawiser , Danilo Marchesini

Classification of intermediate redshift ($z$ = 0.3--0.8) emission line galaxies as star-forming galaxies, composite galaxies, active galactic nuclei (AGN), or low-ionization nuclear emission regions (LINERs) using optical spectra alone was…

We present an extension of the pop-cosmos model for the evolving galaxy population up to redshift $z\sim6$. The model is trained on distributions of observed colors and magnitudes, from 26-band photometry of $\sim420,000$ galaxies in the…

In this study, a new Stacked Generalization technique called Fuzzy Stacked Generalization (FSG) is proposed to minimize the difference between N -sample and large-sample classification error of the Nearest Neighbor classifier. The proposed…

Machine Learning · Computer Science 2013-08-14 Mete Ozay , Fatos T. Yarman Vural

A combination of ground-based (NTT and VLT) and HST (HDF-N and HDF-S) public imaging surveys have been used to collect a sample of 1712 I-selected and 319 $K\leq 21$ galaxies. Photometric redshifts have been obtained for all these galaxies.…

Astrophysics · Physics 2009-10-31 A. Fontana , N. Menci , S. D'Odorico , E. Giallongo , F. Poli , S. Cristiani , A. Moorwood , P. Saracco

We measure the evolution of galaxy clustering out to a redshift of z~1.5 using data from two MUSYC fields, the Extended Hubble Deep Field South (EHDF-S) and the Extended Chandra Deep Field South (ECDF-S). We use photometric redshift…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-19 Nelson Padilla , Daniel Christlein , Eric Gawiser , Roberto González , Lucia Guaita , Leopoldo Infante

We use photometric redshifts to analyse the effect of local environment on galaxy colours at redshifts z < 0.63 in the SDSS data release 6. We construct mock SDSS-DR6 catalogues using semi-analytic galaxies to study possible systematic…

Astrophysics · Physics 2009-11-13 Ana Laura O'Mill , Nelson Padilla , Diego Garcia Lambas

Derivation of physical properties of galaxies using spectral energy distribution (SED) fitting is a powerful method, but can suffer from various systematics arising from model assumptions. Previously, such biases were mostly studied in the…

Astrophysics of Galaxies · Physics 2022-04-27 Katherine Zine , Samir Salim

In order to understand the formation and subsequent evolution of galaxies one must first distinguish between the two main morphological classes of massive systems: spirals and early-type systems. This paper introduces a project, Galaxy Zoo,…

We propose a new soft clustering scheme for classifying galaxies in different activity classes using simultaneously 4 emission-line ratios; log([NII ]/Ha), log([SII]/Ha), log([OI]/Ha) and log([OIII]/Hb). We fit 20 multivariate Gaussian…

Astrophysics of Galaxies · Physics 2019-02-20 Vasileios Stampoulis , David A. van Dyk , Vinay L. Kashyap , Andreas Zezas

We develop a straightforward and quantitative two-step method for spectroscopically classifying galaxies from the low signal-to-noise (S/N) optical spectra typical of galaxy redshift surveys. First, using \chi^2-fitting of characteristic…

Astrophysics · Physics 2009-10-28 Dennis Zaritsky , Ann I. Zabludoff , Jeffrey A. Willick

Compact groups of galaxies provide insight into the role of low-mass, dense environments in galaxy evolution because the low velocity dispersions and close proximity of galaxy members result in frequent interactions that take place over…

Recently, several studies have claimed that using class-specific feature subsets provides certain advantages over using a single feature subset for representing the data for a classification problem. Unlike traditional feature selection…

Machine Learning · Computer Science 2023-07-11 Suchismita Das , Nikhil R. Pal

We present the galaxy-galaxy angular correlations as a function of photometric redshift in a deep-wide galaxy survey centered on the Hubble Deep Field South. Images were obtained with the Big Throughput Camera on the Blanco 4m telescope at…

We study the evolution of galaxy populations around the spectroscopic WiggleZ sample of starforming galaxies at 0.25 < z < 0.75 using the photometric catalog from the Second Red-Sequence Cluster Survey (RCS2). We probe the optical…

The VIMOS-VLT Deep Survey (VVDS) currently offers a unique combination of depth, angular size and number of measured galaxies among surveys of the distant Universe: ~ 11,000 spectra over 0.5 deg2 to I_{AB}=24 (VVDS-Deep), 35,000 spectra…