The galaxy two-point correlation function down to V = 26 magnitudes on 0°.5 scales

Lyman W. Neuschaefer, Rogier Windhorst, Alan Dressler

Research output: Contribution to journalArticle

40 Citations (Scopus)

Abstract

We extend the measurement of the galaxy angular two-point correlation function w(θ) down to V ∼ 26 mag on scales θ ≲ 0°.45. For this, we used the Palomar 200 inch (5.08 m) Four-Shooter CCD-array to image two deep radio-optical survey regions (0.2 deg2) with contiguous mosaics in Gunn gri, yielding in total ∼ 60,000 faint galaxies down to V ∼ 26 mag. Here, we present the first results for one mosaic in Gunn g. In the entire magnitude range 14 ≲ g ≲ 26 mag, w(θ) is consistent with a power law of the form w(θ) = Aωθ1-γ and roughly maintains a constant slope (1 - γ ≃ -0.6 to -0.8). The slope of w(θ) has thus apparently undergone little change over the entire redshift range sampled for 14 ≲ g ≲ 26 mag. For 20 ≲ g ≲ 24.5 mag, the amplitude of w(θ) - Aω- continues to decrease toward fainter magnitudes. Beyond g ≳ 25 mag, our catalogs become gradually incomplete, and Aω starts to rise again while maintaining roughly the same slope. In order of expected importance, possible explanations for this effect are: (1) differential incompleteness between chips (due to sensitivity, seeing, and/or focus variations); (2) the systematic selection at the faintest magnitudes of the highest surface brightness galaxies, which are known locally to cluster more strongly than low surface brightness galaxies; (3) an increasing fraction of faint objects could be distant subgalactic clumps that still have to merge into single L* galaxies; (4) the faint galaxy counts (g ≳ 25 mag) are dominated by a population of nearby dwarf galaxies, so that zmed starts to decrease again for g ≳ 25 mag; (5) if Ω ≃ 1 and zmed ≳ 1.25 for g ≳ 25 mag, the θ-z relation would go through a minimum, causing w(θ) to move toward larger θ at fainter magnitudes or higher redshifts.

Original languageEnglish (US)
Pages (from-to)32-43
Number of pages12
JournalAstrophysical Journal
Volume382
Issue number1
StatePublished - Nov 20 1991

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galaxies
slopes
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Keywords

  • Cosmology
  • Galaxies: clustering
  • Galaxies: evolution

ASJC Scopus subject areas

  • Space and Planetary Science

Cite this

The galaxy two-point correlation function down to V = 26 magnitudes on 0°.5 scales. / Neuschaefer, Lyman W.; Windhorst, Rogier; Dressler, Alan.

In: Astrophysical Journal, Vol. 382, No. 1, 20.11.1991, p. 32-43.

Research output: Contribution to journalArticle

Neuschaefer, Lyman W. ; Windhorst, Rogier ; Dressler, Alan. / The galaxy two-point correlation function down to V = 26 magnitudes on 0°.5 scales. In: Astrophysical Journal. 1991 ; Vol. 382, No. 1. pp. 32-43.
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abstract = "We extend the measurement of the galaxy angular two-point correlation function w(θ) down to V ∼ 26 mag on scales θ ≲ 0°.45. For this, we used the Palomar 200 inch (5.08 m) Four-Shooter CCD-array to image two deep radio-optical survey regions (0.2 deg2) with contiguous mosaics in Gunn gri, yielding in total ∼ 60,000 faint galaxies down to V ∼ 26 mag. Here, we present the first results for one mosaic in Gunn g. In the entire magnitude range 14 ≲ g ≲ 26 mag, w(θ) is consistent with a power law of the form w(θ) = Aωθ1-γ and roughly maintains a constant slope (1 - γ ≃ -0.6 to -0.8). The slope of w(θ) has thus apparently undergone little change over the entire redshift range sampled for 14 ≲ g ≲ 26 mag. For 20 ≲ g ≲ 24.5 mag, the amplitude of w(θ) - Aω- continues to decrease toward fainter magnitudes. Beyond g ≳ 25 mag, our catalogs become gradually incomplete, and Aω starts to rise again while maintaining roughly the same slope. In order of expected importance, possible explanations for this effect are: (1) differential incompleteness between chips (due to sensitivity, seeing, and/or focus variations); (2) the systematic selection at the faintest magnitudes of the highest surface brightness galaxies, which are known locally to cluster more strongly than low surface brightness galaxies; (3) an increasing fraction of faint objects could be distant subgalactic clumps that still have to merge into single L* galaxies; (4) the faint galaxy counts (g ≳ 25 mag) are dominated by a population of nearby dwarf galaxies, so that zmed starts to decrease again for g ≳ 25 mag; (5) if Ω ≃ 1 and zmed ≳ 1.25 for g ≳ 25 mag, the θ-z relation would go through a minimum, causing w(θ) to move toward larger θ at fainter magnitudes or higher redshifts.",
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AB - We extend the measurement of the galaxy angular two-point correlation function w(θ) down to V ∼ 26 mag on scales θ ≲ 0°.45. For this, we used the Palomar 200 inch (5.08 m) Four-Shooter CCD-array to image two deep radio-optical survey regions (0.2 deg2) with contiguous mosaics in Gunn gri, yielding in total ∼ 60,000 faint galaxies down to V ∼ 26 mag. Here, we present the first results for one mosaic in Gunn g. In the entire magnitude range 14 ≲ g ≲ 26 mag, w(θ) is consistent with a power law of the form w(θ) = Aωθ1-γ and roughly maintains a constant slope (1 - γ ≃ -0.6 to -0.8). The slope of w(θ) has thus apparently undergone little change over the entire redshift range sampled for 14 ≲ g ≲ 26 mag. For 20 ≲ g ≲ 24.5 mag, the amplitude of w(θ) - Aω- continues to decrease toward fainter magnitudes. Beyond g ≳ 25 mag, our catalogs become gradually incomplete, and Aω starts to rise again while maintaining roughly the same slope. In order of expected importance, possible explanations for this effect are: (1) differential incompleteness between chips (due to sensitivity, seeing, and/or focus variations); (2) the systematic selection at the faintest magnitudes of the highest surface brightness galaxies, which are known locally to cluster more strongly than low surface brightness galaxies; (3) an increasing fraction of faint objects could be distant subgalactic clumps that still have to merge into single L* galaxies; (4) the faint galaxy counts (g ≳ 25 mag) are dominated by a population of nearby dwarf galaxies, so that zmed starts to decrease again for g ≳ 25 mag; (5) if Ω ≃ 1 and zmed ≳ 1.25 for g ≳ 25 mag, the θ-z relation would go through a minimum, causing w(θ) to move toward larger θ at fainter magnitudes or higher redshifts.

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