ASPECT: A spectra clustering tool for exploration of large spectral surveys

Abstract

We present the novel, semi-automated clustering tool ASPECT for analysing voluminous archives of spectra. The heart of the program is a neural network in form of Kohonen's self-organizing map. The resulting map is designed as an icon map suitable for the inspection by eye. The visual analysis is supported by the option to blend in individual object properties such as redshift, apparent magnitude, or signal-to-noise ratio. In addition, the package provides several tools for the selection of special spectral types, e.g. local difference maps which reflect the deviations of all spectra from one given input spectrum (real or artificial). ASPECT is able to produce a two-dimensional topological map of a huge number of spectra. The software package enables the user to browse and navigate through a huge data pool and helps him to gain an insight into underlying relationships between the spectra and other physical properties and to get the big picture of the entire data set. We demonstrate the capability of ASPECT by clustering the entire data pool of 0.6 million spectra from the Data Release 4 of the Sloan Digital Sky Survey (SDSS). To illustrate the results regarding quality and completeness we track objects from existing catalogues of quasars and carbon stars, respectively, and connect the SDSS spectra with morphological information from the GalaxyZoo project.

arXiv comment15 pages, 14 figures; accepted for publication in Astronomy and Astrophysics

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Cited by in corpus (9)

• SOMz: photometric redshift PDFs with self organizing maps and random atlas
• An automatic taxonomy of galaxy morphology using unsupervised machine learning
• A large sample of Kohonen-selected SDSS quasars with weak emission lines: selection effects and statistical properties
• Data mining techniques on astronomical spectra data. I : Clustering Analysis
• A large sample of Kohonen selected E+A (post-starburst) galaxies from the Sloan Digital Sky Survey
• On the fundamentality of the radial acceleration relation for late-type galaxy dynamics
• Broad-band spectral energy distribution of 3000 Angstroem break quasars from the Sloan Digital Sky Survey
• Galaxy Manifold: Characterizing and understanding galaxies with two parameters
• A Treasure Hunt in the Pool of Spectra Classified as High-redshift QSOs by the Spectroscopic Pipeline of the SDSS DR16