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Related papers: Unsupervised Classification of Galaxies. I. ICA fe…

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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

The large amount of data on galaxies, up to higher and higher redshifts, asks for sophisticated statistical approaches to build adequate classifications. Multivariate cluster analyses, that compare objects for their global similarities, are…

Cosmology and Nongalactic Astrophysics · Physics 2011-06-22 Didier Fraix-Burnet

Group studies involving large cohorts of subjects are important to draw general conclusions about brain functional organization. However, the aggregation of data coming from multiple subjects is challenging, since it requires accounting for…

Machine Learning · Statistics 2020-12-25 Hugo Richard , Luigi Gresele , Aapo Hyvärinen , Bertrand Thirion , Alexandre Gramfort , Pierre Ablin

We use narrow-band Halpha+[NII] imaging data gathered during VESTIGE, a blind survey of the Virgo cluster carried out with MegaCam at the CFHT, to identify HII regions in 385 galaxies showing ionised gas emission. We identify 76645 HII…

Astrophysics of Galaxies · Physics 2026-05-07 A. Boselli , M. Fossati , Y. Roehlly , M. Boquien , J. Braine , P. Cote , J. C. Cuillandre , B. Epinat , L. Ferrarese , S. Gwyn , G. Hensler

We present the construction and describe the properties of the Padova-Millennium Galaxy and Group Catalogue (PM2GC), a galaxy catalogue representative of the general field population in the local Universe. We characterize galaxy…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-28 Rosa Calvi , Bianca M. Poggianti , Benedetta Vulcani

Galaxies host a wide array of internal stellar components, which need to be decomposed accurately in order to understand their formation and evolution. While significant progress has been made with recent integral-field spectroscopic…

Astrophysics of Galaxies · Physics 2019-11-06 Min Du , Luis C. Ho , Dongyao Zhao , Jingjing Shi , Victor P. Debattista , Lars Hernquist , Dylan Nelson

We investigate the integrated spectra of a sample of 24 normal galaxies. A principal component analysis suggests that most of the variance present in the spectra is due to the differences in morphology of the galaxies in the sample. We show…

Astrophysics · Physics 2009-10-22 Laerte Sodre , Hector Cuevas

An analysis of the protein content of several crystal forms of proteins has been performed. We apply a new numerical technique, the Independent Component Analysis (ICA), to determine the volume fraction of the asymmetric unit occupied by…

Quantitative Methods · Quantitative Biology 2008-12-02 Antonio Lamura , Massimo Ladisa , Giovanni Nico , Dritan Siliqi

The primary distance indicators are established in our Galaxy and the Local Group. There are at least four different methods which give good distances: methods using proper motions, RR Lyraes, Cepheid variables, and Type II supernovae.…

Astrophysics · Physics 2009-10-28 Dragan Huterer , Dimitar D. Sasselov , Paul L. Schechter

We analyze empirical relationships between the optical, near infrared, and HI characteristics of isolated galaxies from the 2MIG Catalog covering the entire sky. Data on morphological types, K_S-, and B-magnitudes, linear diameters, HI…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-03 Yu. N. Kudrya , V. E. Karachentseva , I. D. Karachentsev

Here, a separation theorem about Independent Subspace Analysis (ISA), a generalization of Independent Component Analysis (ICA) is proven. According to the theorem, ISA estimation can be executed in two steps under certain conditions. In the…

Statistics Theory · Mathematics 2007-06-13 Zoltan Szabo , Barnabas Poczos , Andras Lorincz

The galaxy evolution is believed to be conditioned by the environment. Isolated galaxies or galaxies in poor groups are an excellent laboratory to study evolutionary mechanisms where effects of the environment are minimal. We present new…

Astrophysics of Galaxies · Physics 2022-03-14 Paola Mazzei , Roberto Rampazzo , Antonietta Marino , Ginevra Trinchieri , Michela Uslenghi , Anna Wolter

Here, we address the problem of Independent Subspace Analysis (ISA). We develop a technique that (i) builds upon joint decorrelation for a set of functions, (ii) can be related to kernel based techniques, (iii) can be interpreted as a…

Statistics Theory · Mathematics 2012-01-04 Zoltan Szabo , Andras Lorincz

Using single-component fits to SDSS/UKIDSS images of galaxies in the G09 region of the GAMA survey we study radial colour gradients across the galaxy population. We use the multiwavelength information provided by MegaMorph analysis of…

To understand the evolution of galaxies, we need to know as accurately as possible how many galaxies were present in the Universe at different epochs. Galaxies in the young Universe have hitherto mainly been identified using their expected…

We study morphology and luminosity segregation of galaxies in loose groups. We analyze the two catalogs of groups which have been identified in the Nearby Optical Galaxy (NOG) sample, by means of hierarchical and percolation…

Astrophysics · Physics 2009-11-07 M. Girardi , E. Rigoni , F. Mardirossian , M. Mezzetti

We present a statistical analysis of the properties of a large sample of dynamically hot old stellar systems, from globular clusters to giant ellipticals, which was performed in order to investigate the origin of ultra-compact dwarf…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-04 Tanuka Chattopadhyay , Margarita Sharina , Emmanuel Davoust , Tuli De , Asis Kumar Chattopadhyay

The Milky Way has distinct structural stellar components linked to its formation and subsequent evolution, but disentangling them is nontrivial. With the recent availability of high-quality data for a large numbers of stars in the Milky…

Astrophysics of Galaxies · Physics 2023-07-05 Amalie Stokholm , Víctor Aguirre Børsen-Koch , Dennis Stello , Marc Hon , Claudia Reyes