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Red and blue galaxies are traditionally classified using some specific cuts in colour or other galaxy properties, which are supported by empirical arguments. The vagueness associated with such cuts are likely to introduce a significant…

Astrophysics of Galaxies · Physics 2020-09-09 Biswajit Pandey

Disk and halo stars are generally classified using several conventional methods, such as the Toomre diagram, sharp cuts in metallicity ([Fe/H]), vertical distance ($\left|Z\right|$) from the Galactic plane, or thresholds on the orbital…

Astrophysics of Galaxies · Physics 2025-12-04 Amit Mondal , Biswajit Pandey

We analyse the u-r color distribution of 24346 galaxies with Mr<=-18 and z<0.08, drawn from the Sloan Digital Sky Survey first data release, as a function of luminosity and environment. The color distribution is well fit with two Gaussian…

We analyze the SDSS data to classify the galaxies based on their colour using a fuzzy set-theoretic method and quantify their environments using the local dimension. We find that the fraction of the green galaxies does not depend on the…

Astrophysics of Galaxies · Physics 2021-07-01 Apashanka Das , Biswajit Pandey , Suman Sarkar

The Sloan Digital Sky Survey (SDSS) and photometric/spectroscopic surveys in the GOODS-South field (the Chandra Deep Field-South, CDFS) are used to construct volume-limited, stellar mass-selected samples of galaxies at redshifts 0<z<1. The…

We present a multiscale approach to measurements of galaxy density, applied to a volume-limited sample constructed from SDSS DR5. We populate a rich parameter space by obtaining independent measurements of density on different scales for…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-18 David Wilman , Stefano Zibetti , Tamas Budavari

The Spectral Galaxy Pairs (SGPs) are defined as the composite galaxy spectra which contain two independent redshift systems. These spectra are useful for studying dust properties of the foreground galaxies. In this paper, a total of 165…

Astrophysics of Galaxies · Physics 2016-11-04 Haifeng Yang , Ali Luo , Xiaoyan Chen , Jifu Zhang , Wen Hou , Jianghui Cai , Peng Wei , Juanjuan Ren , Xiaojie Liu , Yongheng Zhao

While we already seem to have a general scenario of the evolution of different types of galaxies, a complete and satisfactory understanding of the processes that led to the formation of all the variety of today's galaxy types is still…

Astrophysics of Galaxies · Physics 2022-11-23 M. Siudek , K. Lisiecki , M. Mezcua , K. Małek , A. Pollo , J. Krywult , A. Karska , Junais

We analyse $u-r$ colour distributions for several samples of galaxies in groups drawn from the Fourth Data Release of the Sloan Digital Sky Survey. For all luminosity ranges and environments considered the colour distributions are well…

Astrophysics · Physics 2009-11-11 Hector J. Martinez , Ana L. O'Mill , Diego G. Lambas

The populations of both quiescent and actively star-forming galaxies at 1<z<2 are still under-represented in our spectroscopic census of galaxies throughout the history of the Universe. In the light of galaxy formation models, however, the…

We apply clustering-based redshift inference to all extended sources from the Sloan Digital Sky Survey photometric catalogue, down to magnitude r = 22. We map the relationships between colours and redshift, without assumption of the…

We identify a sample of 324 red and 273 blue face-on spiral galaxies selected from 115 low-redshift (0.014 < z < 0.18) galaxy clusters imaged with CFHT+MegaCam in u- and r-band, KPNO 0.9-meter 2TKA and MOSAIC 8K camera in B and Rc, and…

Galaxies broadly fall into two categories: star-forming (blue) galaxies and quiescent (red) galaxies. In between, one finds the less populated ``green valley". Some of these galaxies are suspected to be in the process of ceasing their…

We analyzed the spatial distribution of 28500 photometrically selected galaxies with AB magnitude 23.5<R<25.5 and redshift 1.4<z<3.5 in 21 fields with a total area of 0.81 square degrees. The galaxies were divided into three subsamples,…

Astrophysics · Physics 2009-11-10 K. L. Adelberger , C. C. Steidel , M. Pettini , A. E. Shapley , N. A. Reddy , D. K. Erb

Understanding the formation and evolution of galaxy populations requires robust classification and characterisation techniques that jointly account for internal galaxy properties and environment. We analyse $5,306$ galaxies from the Galaxy…

Astrophysics of Galaxies · Physics 2026-05-25 Fan Dai , Ranjan Maitra , Ivan K. Baldry

We explore the constraints that can be placed on the evolutionary timescales for typical low redshift galaxies evolving from the blue cloud through the green valley and onto the red sequence. We utilise galaxies from the GAMA survey with…

To explore the evolutionary connection among red, green, and blue galaxy populations, based on a sample of massive ($M_* > 10^{10} M_{\odot} $) galaxies at 0.5<z<2.5 in five 3D-HST/CANDELS fields, we investigate the dust content,…

Astrophysics of Galaxies · Physics 2018-04-16 Yizhou Gu , Guanwen Fang , Qirong Yuan , Zhenyi Cai , Tao Wang

We explore constraints on the joint photometric and morphological evolution of typical low redshift galaxies as they move from the blue cloud through the green valley and onto the red sequence. We select GAMA survey galaxies with…

We analyze the evolution of red and blue galaxies in different cosmic web environments from redshift $z=3$ to $z=0$ using the IllustrisTNG simulation. We use Otsu's method to classify the red or blue galaxies at each redshift and determine…

Astrophysics of Galaxies · Physics 2025-09-24 Biswajit Pandey , Anindita Nandi
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