Detailed decomposition of galaxy images. II. beyond axisymmetric models

Chien Y. Peng, Luis C. Ho, Christopher D Impey, Hans Walter Rix

Research output: Contribution to journalArticle

756 Citations (Scopus)

Abstract

We present a two-dimensional (2D) fitting algorithm (GALFIT, ver. 3) with new capabilities to study the structural components of galaxies and other astronomical objects in digital images. Our technique improves on previous 2D fitting algorithms by allowing for irregular, curved, logarithmic and power-law spirals, ring, and truncated shapes in otherwise traditional parametric functions like the Sérsic, Moffat, King, Ferrer, etc., profiles. One can mix and match these new shape features freely, with or without constraints, and apply them to an arbitrary number of model components of numerous profile types, so as to produce realistic-looking galaxy model images. Yet, despite the potential for extreme complexity, the meaning of the key parameters like the Sérsic index, effective radius, or luminosity remains intuitive and essentially unchanged. The new features have an interesting potential for use to quantify the degree of asymmetry of galaxies, to quantify low surface brightness tidal features beneath and beyond luminous galaxies, to allow more realistic decompositions of galaxy subcomponents in the presence of strong rings and spiral arms, and to enable ways to gauge the uncertainties when decomposing galaxy subcomponents. We illustrate these new features by way of several case studies that display various levels of complexity.

Original languageEnglish (US)
Pages (from-to)2097-2129
Number of pages33
JournalAstronomical Journal
Volume139
Issue number6
DOIs
StatePublished - 2010

Fingerprint

decomposition
galaxies
structural component
digital image
gauge
asymmetry
power law
rings
profiles
brightness
luminosity
radii
index
parameter

Keywords

  • Galaxies: bulges
  • Galaxies: fundamental parameters
  • Galaxies: structure
  • Techniques: image processing
  • Techniques: photometric

ASJC Scopus subject areas

  • Space and Planetary Science
  • Astronomy and Astrophysics

Cite this

Detailed decomposition of galaxy images. II. beyond axisymmetric models. / Peng, Chien Y.; Ho, Luis C.; Impey, Christopher D; Rix, Hans Walter.

In: Astronomical Journal, Vol. 139, No. 6, 2010, p. 2097-2129.

Research output: Contribution to journalArticle

Peng, Chien Y. ; Ho, Luis C. ; Impey, Christopher D ; Rix, Hans Walter. / Detailed decomposition of galaxy images. II. beyond axisymmetric models. In: Astronomical Journal. 2010 ; Vol. 139, No. 6. pp. 2097-2129.
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