Gravitational lensing and dark structures

Yu Chung N Cheng, Lawrence Krauss

Research output: Contribution to journalArticle

10 Citations (Scopus)

Abstract

We examine whether a cosmologically significant distribution of dark galaxy group or cluster-sized objects can have an optical depth for multiple imaging of distant background sources, which is comparable with that from known galaxies while at the same time producing angular splittings of the same order of magnitude. Our purpose is to explore whether such objects could realistically account for some of the observed lenses. Modeling such systems as isothermal spheres with core radii and assuming a Schechter-type distribution function, we find that independent of the cosmology (open, flat matter-dominated, or flat cosmological constant-dominated) an allowed, albeit narrow, parameter range exists that is comparable in velocity dispersion with that for known compact groups of galaxies, although the preferred core radii are somewhat smaller than that normally assumed for compact groups. Dark cluster-sized objects, on the other hand, cannot reproduce the observed lensing characteristics. If the one known dark cluster were a good representative of such a distribution, most such objects would not produce multiple images. We also present a result for the angular splitting from an isothermal sphere lens with nonzero core radius, extending earlier work of Hinshaw & Krauss. Our results are expressed as contour plots for fixed lensing probabilities and angular splittings.

Original languageEnglish (US)
Pages (from-to)25-32
Number of pages8
JournalAstrophysical Journal
Volume514
Issue number1 PART 1
StatePublished - Mar 20 1999
Externally publishedYes

Fingerprint

radii
lenses
galaxies
galactic clusters
cosmology
optical thickness
optical depth
plots
distribution functions
modeling
distribution
parameter

Keywords

  • Dark matter
  • Galaxies: clusters: general
  • Galaxies: fundamental parameters
  • Galaxies: statistics
  • Gravitational lensing

ASJC Scopus subject areas

  • Space and Planetary Science

Cite this

Cheng, Y. C. N., & Krauss, L. (1999). Gravitational lensing and dark structures. Astrophysical Journal, 514(1 PART 1), 25-32.

Gravitational lensing and dark structures. / Cheng, Yu Chung N; Krauss, Lawrence.

In: Astrophysical Journal, Vol. 514, No. 1 PART 1, 20.03.1999, p. 25-32.

Research output: Contribution to journalArticle

Cheng, YCN & Krauss, L 1999, 'Gravitational lensing and dark structures', Astrophysical Journal, vol. 514, no. 1 PART 1, pp. 25-32.
Cheng YCN, Krauss L. Gravitational lensing and dark structures. Astrophysical Journal. 1999 Mar 20;514(1 PART 1):25-32.
Cheng, Yu Chung N ; Krauss, Lawrence. / Gravitational lensing and dark structures. In: Astrophysical Journal. 1999 ; Vol. 514, No. 1 PART 1. pp. 25-32.
@article{44b81137d8ad4ba58c0a0861fe87e3e4,
title = "Gravitational lensing and dark structures",
abstract = "We examine whether a cosmologically significant distribution of dark galaxy group or cluster-sized objects can have an optical depth for multiple imaging of distant background sources, which is comparable with that from known galaxies while at the same time producing angular splittings of the same order of magnitude. Our purpose is to explore whether such objects could realistically account for some of the observed lenses. Modeling such systems as isothermal spheres with core radii and assuming a Schechter-type distribution function, we find that independent of the cosmology (open, flat matter-dominated, or flat cosmological constant-dominated) an allowed, albeit narrow, parameter range exists that is comparable in velocity dispersion with that for known compact groups of galaxies, although the preferred core radii are somewhat smaller than that normally assumed for compact groups. Dark cluster-sized objects, on the other hand, cannot reproduce the observed lensing characteristics. If the one known dark cluster were a good representative of such a distribution, most such objects would not produce multiple images. We also present a result for the angular splitting from an isothermal sphere lens with nonzero core radius, extending earlier work of Hinshaw & Krauss. Our results are expressed as contour plots for fixed lensing probabilities and angular splittings.",
keywords = "Dark matter, Galaxies: clusters: general, Galaxies: fundamental parameters, Galaxies: statistics, Gravitational lensing",
author = "Cheng, {Yu Chung N} and Lawrence Krauss",
year = "1999",
month = "3",
day = "20",
language = "English (US)",
volume = "514",
pages = "25--32",
journal = "Astrophysical Journal",
issn = "0004-637X",
publisher = "IOP Publishing Ltd.",
number = "1 PART 1",

}

TY - JOUR

T1 - Gravitational lensing and dark structures

AU - Cheng, Yu Chung N

AU - Krauss, Lawrence

PY - 1999/3/20

Y1 - 1999/3/20

N2 - We examine whether a cosmologically significant distribution of dark galaxy group or cluster-sized objects can have an optical depth for multiple imaging of distant background sources, which is comparable with that from known galaxies while at the same time producing angular splittings of the same order of magnitude. Our purpose is to explore whether such objects could realistically account for some of the observed lenses. Modeling such systems as isothermal spheres with core radii and assuming a Schechter-type distribution function, we find that independent of the cosmology (open, flat matter-dominated, or flat cosmological constant-dominated) an allowed, albeit narrow, parameter range exists that is comparable in velocity dispersion with that for known compact groups of galaxies, although the preferred core radii are somewhat smaller than that normally assumed for compact groups. Dark cluster-sized objects, on the other hand, cannot reproduce the observed lensing characteristics. If the one known dark cluster were a good representative of such a distribution, most such objects would not produce multiple images. We also present a result for the angular splitting from an isothermal sphere lens with nonzero core radius, extending earlier work of Hinshaw & Krauss. Our results are expressed as contour plots for fixed lensing probabilities and angular splittings.

AB - We examine whether a cosmologically significant distribution of dark galaxy group or cluster-sized objects can have an optical depth for multiple imaging of distant background sources, which is comparable with that from known galaxies while at the same time producing angular splittings of the same order of magnitude. Our purpose is to explore whether such objects could realistically account for some of the observed lenses. Modeling such systems as isothermal spheres with core radii and assuming a Schechter-type distribution function, we find that independent of the cosmology (open, flat matter-dominated, or flat cosmological constant-dominated) an allowed, albeit narrow, parameter range exists that is comparable in velocity dispersion with that for known compact groups of galaxies, although the preferred core radii are somewhat smaller than that normally assumed for compact groups. Dark cluster-sized objects, on the other hand, cannot reproduce the observed lensing characteristics. If the one known dark cluster were a good representative of such a distribution, most such objects would not produce multiple images. We also present a result for the angular splitting from an isothermal sphere lens with nonzero core radius, extending earlier work of Hinshaw & Krauss. Our results are expressed as contour plots for fixed lensing probabilities and angular splittings.

KW - Dark matter

KW - Galaxies: clusters: general

KW - Galaxies: fundamental parameters

KW - Galaxies: statistics

KW - Gravitational lensing

UR - http://www.scopus.com/inward/record.url?scp=0033586104&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=0033586104&partnerID=8YFLogxK

M3 - Article

VL - 514

SP - 25

EP - 32

JO - Astrophysical Journal

JF - Astrophysical Journal

SN - 0004-637X

IS - 1 PART 1

ER -