Automated galaxy morphology

A Fourier approach

S. C. Odewahn, S. H. Cohen, Rogier Windhorst, Ninan Sajeeth Philip

Research output: Contribution to journalArticle

42 Citations (Scopus)

Abstract

We use automated surface photometry and pattern classification techniques to morphologically classify galaxies. The two-dimensional light distribution of a galaxy is reconstructed using Fourier series fits to azimuthal profiles computed in concentric elliptical annuli centered on the galaxy. Both the phase and amplitude of each Fourier component have been studied as a function of radial bin number for a large collection of galaxy images using principal-component analysis. We find that up to 90% of the variance in many of these Fourier profiles may be characterized in as few as three principal components and that their use substantially reduces the dimensionality of the classification problem. We use supervised learning methods in the form of artificial neural networks to train galaxy classifiers that detect morphological bars at the 85%-90% confidence level and can identify the Hubble type with a 1 σ scatter of 1.5 steps on the 16 step stage axis of the revised Hubble system. Finally, we systematically characterize the adverse effects of decreasing resolution and signal-to-noise ratio on the quality of morphological information predicted by these classifiers.

Original languageEnglish (US)
Pages (from-to)539-557
Number of pages19
JournalAstrophysical Journal
Volume568
Issue number2 I
DOIs
StatePublished - Apr 1 2002

Fingerprint

galaxies
artificial neural network
signal-to-noise ratio
train
principal component analysis
classifiers
Fourier series
annuli
profiles
principal components analysis
learning
photometry
confidence
signal to noise ratios
distribution
supervised learning
effect
method

Keywords

  • Galaxies: fundamental parameters (classification)
  • Galaxies: structure methods: data analysis

ASJC Scopus subject areas

  • Space and Planetary Science

Cite this

Odewahn, S. C., Cohen, S. H., Windhorst, R., & Philip, N. S. (2002). Automated galaxy morphology: A Fourier approach. Astrophysical Journal, 568(2 I), 539-557. https://doi.org/10.1086/339036

Automated galaxy morphology : A Fourier approach. / Odewahn, S. C.; Cohen, S. H.; Windhorst, Rogier; Philip, Ninan Sajeeth.

In: Astrophysical Journal, Vol. 568, No. 2 I, 01.04.2002, p. 539-557.

Research output: Contribution to journalArticle

Odewahn, SC, Cohen, SH, Windhorst, R & Philip, NS 2002, 'Automated galaxy morphology: A Fourier approach', Astrophysical Journal, vol. 568, no. 2 I, pp. 539-557. https://doi.org/10.1086/339036
Odewahn, S. C. ; Cohen, S. H. ; Windhorst, Rogier ; Philip, Ninan Sajeeth. / Automated galaxy morphology : A Fourier approach. In: Astrophysical Journal. 2002 ; Vol. 568, No. 2 I. pp. 539-557.
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