The morphologies of distant galaxies. 1: an automated classification system

Abraham, Roberto; Valdés, Francisco; Yee, H. K. C.; Bergh, Sidney van den

doi:10.1086/174550

Cited by 327 publications

(384 citation statements)

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“…Concentration parameters are correlated to B/D or to the ratio of bulge to total light (de Vaucouleurs 1977 ;Okamura et al 1984 ;Kent 1985 ;Eder 1990 ; but see Naim, Ratnatunga, & Griffiths 1997) and Hubble type (Abraham et al 1994) of spiral galaxies, although they may be less sensitive in di †erentiating Sa, S0, and E galaxies (Abraham et al 1994 ;Smail et al 1997 ;van den Bergh 1997) and they are somewhat dependent on a galaxyÏs surface brightness (e.g., Abraham et al 1994). Unlike B/D, concentration parameters are independent of models assumed for galaxy components.…”

Section: R Concentration Parametermentioning

confidence: 99%

An Atlas of Hα and R Images and Radial Profiles of 63 Bright Virgo Cluster Spiral Galaxies

Koopmann

Kenney

Young

2001

ASTROPHYS J SUPPL S

123

141

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Section: R Concentration Parametermentioning

confidence: 99%

An Atlas of Hα and R Images and Radial Profiles of 63 Bright Virgo Cluster Spiral Galaxies

Koopmann

Kenney

Young

2001

ASTROPHYS J SUPPL S

123

141

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“…As noted in several instances below, the intrinsic patchiness and low signal-to-noise ratio of the FUV images have posed special difficulties for the techniques typically used to measure C and A. We have therefore modiÐed the deÐnitions proposed by Abraham et al (1994Abraham et al ( , 1996aAbraham et al ( , 1996b, while retaining the general idea of a correlation between high concentration plus symmetry and an ordered appearance. The e †ects of these modiÐcations will be explored later in this section.…”

Section: Concentration and Asymmetry Indicesmentioning

confidence: 99%

“…In practice, di †erent authors have measured C using a variety of deÐnitions (Doi et al 1993 ;Abraham et al 1994 ;Naim, Ratnatunga, & Griffiths 1997). We select a very simple expression :…”

Section: Concentration and Asymmetry Indicesmentioning

confidence: 99%

“…The emerging methods are, by design, easily applicable to the current generation of large CCD imaging surveys. Abraham et al (1994) developed a numerical index for the central concentration (C) of galaxies, following the Yerkes classiÐcation system of Morgan (1958) and the correlations between concentration and Hubble type presented by Okamura, Kodaira, & Watanabe (1984) and Doi, Fukugita, & Okamura (1993). These authors later (Abraham et al 1996b) added a quantitative measure of galaxy asymmetry (A) to form a two-part classiÐcation system that distinguishes three bins : E/S0 galaxies, spiral galaxies, and irregular or peculiar systems.…”

Section: Introductionmentioning

confidence: 99%

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Quantitative Morphology of Galaxies Observed in the Ultraviolet

Kuchinski

Madore

Freedman

et al. 2001

The Astronomical Journal

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We present a quantitative study of the far-ultraviolet (FUV) and optical morphology in 32 nearby galaxies and estimate the "" morphological k-correction ÏÏ expected if these objects were observed unevolved at high redshift. Using the common indices of central concentration (C) and rotational asymmetry (A) to quantify morphology, we consider independently two phenomena that give rise to this kcorrection. Bandshifting, the decrease in the rest-frame wavelength of light observed through optical Ðlters, is explored by measuring these indices in several passbands for each galaxy, and it is found to be the primary driver of changes in C and A. In general, the optical trend found for decreasing C and increasing A when going to shorter wavelengths extends to the FUV. However, the patchy nature of recent star formation in late-type galaxies, which is accentuated in the FUV, results in poor quantitative correspondence between morphologies determined in the optical and FUV. We then artiÐcially redshift our FUV images into the Hubble Deep Field (HDF) Ðlters to simulate various cosmological distance e †ects, such as surface brightness dimming and loss of spatial resolution. Hubble types of many galaxies in our sample are not readily identiÐable at redshifts beyond z D 1, and the galaxies themselves are difficult to detect beyond z D 3. Because only features of the highest surface brightness remain visible at cosmological distances, the change in C and A between simulated high-z galaxies and their unredshifted counterparts depends on whether their irregular features are primarily bright or faint. Our simulations suggest that k-corrections alone are indeed capable of producing the peculiar morphologies observed at high redshift ; for example, several spiral galaxies have C and A indices typical of irregular or peculiar HDF objects viewed at z º 2. We brieÑy discuss some elements of a scheme to classify rest-frame UV images, mergers, protogalaxies, and other objects for which classical Hubble types do not adequately encompass the existing morphology.

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“…These classifiers can be either parametric (model-based) or nonparametric. Nonparametric classifiers include the C ÀA system (Watanabe, Kodaira, & Okamura 1985;Abraham et al 1994Abraham et al , 1996Wu 1999; Conselice, Bershady, & Jangren 2000), artificial neural nets trained from visual classification sets (Odewahn 1995;Odewahn et al 1996), and self-organizing maps (Naim, Ratnatunga, & Griffiths 1997). Parametric classifiers include radial multi-Gaussian deconvolution (Bendinelli 1991;Fasano et al 1998) and bulge + disk decomposition (Schade et al 1995(Schade et al , 1996Ratnatunga, Griffiths, & Ostrander 1999).…”

Section: Introductionmentioning

confidence: 99%

The DEEP Groth Strip Survey. II. Hubble Space Telescope Structural Parameters of Galaxies in the Groth Strip

Simard

Willmer

Vogt

et al. 2002

ASTROPHYS J SUPPL S

410

176

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The quantitative morphological classification of distant galaxies is essential to the understanding of the evolution of galaxies over the history of the universe. This paper presents Hubble Space Telescope WFPC2 F606W and F814W photometric structural parameters for 7450 galaxies in the '' Groth Strip.'' These parameters are based on a two-dimensional bulge + disk surface brightness model and were obtained using an automated reduction and analysis pipeline described in detail here. A first set of fits was performed separately in each bandpass, and a second set of fits was performed simultaneously on both bandpasses. The information produced by these two types of fits can be used to explore different science goals. Systematic and random fitting errors in all structural parameters as well as bulge and disk colors are carefully characterized through extensive sets of simulations. The results of these simulations are given in catalogs similar to the real science catalogs so that both real and simulated measurements can be sampled according to the same selection criteria to show biases and errors in the science data subset of interest. The effects of asymmetric structures on the recovered bulge+disk fitting parameters are also explored through simulations. The full multidimensional photometric survey selection function of the Groth Strip is also computed. This selection function, coupled to bias maps from simulations, provides a complete and objective reproduction of the observational limits, and these limits can be applied to theoretical predictions from galaxy evolution models for direct comparisons with the data.

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The morphologies of distant galaxies. 1: an automated classification system

Cited by 327 publications

References 0 publications

An Atlas of Hα and R Images and Radial Profiles of 63 Bright Virgo Cluster Spiral Galaxies

An Atlas of Hα and R Images and Radial Profiles of 63 Bright Virgo Cluster Spiral Galaxies

Quantitative Morphology of Galaxies Observed in the Ultraviolet

The DEEP Groth Strip Survey. II. Hubble Space Telescope Structural Parameters of Galaxies in the Groth Strip

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