Please use this identifier to cite or link to this item:
http://hdl.handle.net/20.500.12386/30139
Title: | The VIMOS Public Extragalactic Redshift Survey (VIPERS). The complexity of galaxy populations at 0.4 < z < 1.3 revealed with unsupervised machine-learning algorithms | Authors: | Siudek, M. Małek, K. Pollo, A. Krakowski, T. IOVINO, Angela SCODEGGIO, MARCO Moutard, T. Zamorani, G. Guzzo, L. GARILLI, BIANCA MARIA ROSA Granett, B. R. BOLZONELLA, MICOL de la Torre, S. ABBAS, Ummi Adami, C. BOTTINI, DARIO CAPPI, Alberto CUCCIATI, Olga Davidzon, I. FRANZETTI, PAOLO Fritz, A. Krywult, J. Le Brun, V. Le Fèvre, O. Maccagni, D. Marulli, F. POLLETTA, MARIA DEL CARMEN Tasca, L. A. M. Tojeiro, R. VERGANI, DANIELA ZANICHELLI, Alessandra Arnouts, S. Bel, J. Branchini, Enzo Franco Coupon, J. DE LUCIA, GABRIELLA Ilbert, O. Haines, C. P. Moscardini, L. Takeuchi, T. T. |
Issue Date: | 2018 | Journal: | ASTRONOMY & ASTROPHYSICS | Number: | 617 | First Page: | A70 | Abstract: | Aims: Various galaxy classification schemes have been developed so far to constrain the main physical processes regulating evolution of different galaxy types. In the era of a deluge of astrophysical information and recent progress in machine learning, a new approach to galaxy classification has become imperative. <BR /> Methods: In this paper, we employ a Fisher Expectation-Maximization (FEM) unsupervised algorithm working in a parameter space of 12 rest-frame magnitudes and spectroscopic redshift. The model (DBk) and the number of classes (12) were established based on the joint analysis of standard statistical criteria and confirmed by the analysis of the galaxy distribution with respect to a number of classes and their properties. This new approach allows us to classify galaxies based on only their redshifts and ultraviolet to near-infrared (UV-NIR) spectral energy distributions. <BR /> Results: The FEM unsupervised algorithm has automatically distinguished 12 classes: 11 classes of VIPERS galaxies and an additional class of broad-line active galactic nuclei (AGNs). After a first broad division into blue, green, and red categories, we obtained a further sub-division into: three red, three green, and five blue galaxy classes. The FEM classes follow the galaxy sequence from the earliest to the latest types, which is reflected in their colours (which are constructed from rest-frame magnitudes used in the classification procedure) but also their morphological, physical, and spectroscopic properties (not included in the classification scheme). We demonstrate that the members of each class share similar physical and spectral properties. In particular, we are able to find three different classes of red passive galaxy populations. Thus, we demonstrate the potential of an unsupervised approach to galaxy classification and we retrieve the complexity of galaxy populations at z ∼ 0.7, a task that usual, simpler, colour-based approaches cannot fulfil. <P />Based on observations collected at the European Southern Observatory, Cerro Paranal, Chile, using the Very Large Telescope under programs 182.A-0886 and partly 070.A-9007. Also based on observations obtained with MegaPrime/MegaCam, a joint project of CFHT and CEA/DAPNIA, at the Canada-France-Hawaii Telescope (CFHT), which is operated by the National Research Council (NRC) of Canada, the Institut National des Sciences de l'Univers of the Centre National de la Recherche Scientifique (CNRS) of France, and the University of Hawaii. This work is based in part on data products produced at TERAPIX and the Canadian Astronomy Data Centre as part of the Canada-France-Hawaii Telescope Legacy Survey, a collaborative project of NRC and CNRS. The VIPERS web site is <A href="http://www.vipers.inaf.it/">http://www.vipers.inaf.it/ | URI: | http://hdl.handle.net/20.500.12386/30139 | URL: | https://www.aanda.org/articles/aa/abs/2018/09/aa32784-18/aa32784-18.html | ISSN: | 0004-6361 | DOI: | 10.1051/0004-6361/201832784 | Bibcode ADS: | 2018A&A...617A..70S | Fulltext: | open |
Appears in Collections: | 1.01 Articoli in rivista |
Files in This Item:
File | Description | Size | Format | |
---|---|---|---|---|
aa32784-18.pdf | Pdf editoriale | 6.51 MB | Adobe PDF | View/Open |
Page view(s)
73
checked on Apr 24, 2024
Download(s)
46
checked on Apr 24, 2024
Google ScholarTM
Check
Altmetric
Altmetric
Items in DSpace are published in Open Access, unless otherwise indicated.