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We present a method for automated classification of galaxies with low signal-to-noise (S/N) spectra typical of redshift surveys. We develop spectral simulations based on the parameters for the 2dF Galaxy Redshift Survey, and with these…

天体物理学 · 物理学 2015-06-24 S. R. Folkes , O. Lahav , S. J. Maddox

Large sky spectroscopic surveys have reached the scale of photometric surveys in terms of sample sizes and data complexity. These huge datasets require efficient, accurate, and flexible automated tools for data analysis and science…

Measuring the physical properties of galaxies such as redshift frequently requires the use of Spectral Energy Distributions (SEDs). SED template sets are, however, often small in number and cover limited portions of photometric color space.…

天体物理仪器与方法 · 物理学 2017-12-13 J. Bryce Kalmbach , Andrew J. Connolly

We describe an Artificial Neural Network (ANN) approach to classification of galaxy images and spectra. ANNs can replicate the classification of galaxy images by a human expert to the same degree of agreement as that between two human…

天体物理学 · 物理学 2007-05-23 Ofer Lahav

A Fourier analysis on galaxy number counts from redshift data of both the Sloan Digital Sky Survey and the 2dF Galaxy Redshift Survey indicates that galaxies have preferred periodic redshift spacings of $\Delta z =$ 0.0102, 0.0246, and…

天体物理学 · 物理学 2008-09-11 John G. Hartnett , Koichi Hirano

A comprehensive study on compactness has been carried out on the 2dF Galaxy Group Catalogue constructed by Merch\'an & Zandivarez. The compactness indexes defined in this work take into account different geometrical constraints in order to…

天体物理学 · 物理学 2009-11-07 A. Zandivarez , M. J. L. Dominguez , C. J. Ragone , H. Muriel , H. J. Martinez

We have constructed a large, statistically complete sample of galaxy clusters serendipitously detected as extended X-ray sources in 647 ROSAT PSPC pointed observations. The survey covers 158 square degrees with a median sample flux limit of…

We present a dataset built for machine learning applications consisting of galaxy photometry, images, spectroscopic redshifts, and structural properties. This dataset comprises 286,401 galaxy images and photometry from the Hyper-Suprime-Cam…

宇宙学与河外天体物理 · 物理学 2024-10-02 Tuan Do , Bernie Boscoe , Evan Jones , Yun Qi Li , Kevin Alfaro

We present a detailed investigation into the recent star formation histories of 5,697 Luminous Red Galaxies (LRGs) based on the Hdelta (4101A) and [OII] (3727A) lines. LRGs are luminous (L>3L*), galaxies which have been selected to have…

Galaxy clusters are the largest structures in Universe. They are very important as both cosmological probes and astrophysical laboratories. Several methods have been developed to detect galaxy clusters with different techniques (optical,…

宇宙学与河外天体物理 · 物理学 2012-10-09 Begoña Ascaso

Using photometric data from the Dark Energy Survey and the Wide-field Infrared Survey Explorer, we estimate photometric redshifts for 105 million galaxies using the nearest-neighbour algorithm. From such a large data base, 151,244 clusters…

宇宙学与河外天体物理 · 物理学 2022-06-07 Z. L. Wen , J. L. Han

Estimating redshifts from broadband photometry is often limited by how accurately we can map the colors of galaxies to an underlying spectral template. Current techniques utilize spectrophotometric samples of galaxies or spectra derived…

天体物理仪器与方法 · 物理学 2025-03-11 John Franklin Crenshaw , Andrew J. Connolly

Using the deep multi-wavelength MUSYC, GOODS, and FIRES surveys we construct a stellar mass-limited sample of galaxies at 2<z<3. The sample comprises 294 galaxies with M>10^11 Solar masses distributed over four independent fields with a…

We present a spectroscopic catalog of (mostly) red galaxies in 24 galaxy clusters in the redshift range 0.17 < z < 0.92 obtained with the LRIS instrument on the Keck I telescope. Here we describe the observations and the galaxy spectra,…

宇宙学与河外天体物理 · 物理学 2015-05-13 Daniel Stern , Raul Jimenez , Licia Verde , S. Adam Stanford , Marc Kamionkowski

We present a description of the observations and data reduction procedures for an extensive spectroscopic and multi-band photometric study of nine high redshift, optically-selected cluster candidates. The primary goal of the survey is to…

天体物理学 · 物理学 2009-10-30 J. B. Oke , Marc Postman , Lori Lubin

We describe a new method of combining optical and infrared photometry to select Luminous Red Galaxies (LRGs) at redshifts $z > 0.6$. We explore this technique using a combination of optical photometry from CFHTLS and HST, infrared…

星系天体物理 · 物理学 2015-04-27 Abhishek Prakash , Timothy C. Licquia , Jeffrey A. Newman , Sandhya M. Rao

Galaxy spectra are essential to probe the spatial distribution of galaxies in our Universe. To better interpret current and future spectroscopic galaxy redshift surveys, it is important to be able to simulate these data sets. We describe…

Two main strategies have been implemented in mapping the local universe: whole-sky 'shallow' surveys and 'deep' surveys over limited parts of the sky. The two approaches complement each other in studying cosmography and statistical…

天体物理学 · 物理学 2007-05-23 Ofer Lahav

We have determined the composite luminosity function (LF) for galaxies in 60 clusters from the 2dF Galaxy Redshift Survey. The LF spans the range $-22.5<M_{b_{\rm J}}<-15$, and is well-fitted by a Schechter function with ${M_{b_{\rm…

The current and forthcoming observations of large samples of high-redshift galaxies selected according to various photometric and spectroscopic criteria can be interpreted in the context of galaxy formation, by means of models of evolving…

天体物理学 · 物理学 2007-05-23 B. Guiderdoni , J. E. G. Devriendt