Determining the hubble constant from the gravitational lens PG 1115+080

Charles Keeton, C. S. Kochanek

Research output: Contribution to journalArticle

82 Citations (Scopus)

Abstract

For the quadruple gravitational lens PG 1115+080, we combine recent measurements of the time delays with new lens models to determine the Hubble constant H0. We explore the effects of systematic uncertainties in the lens models on the estimates of H0, and we discuss how the uncertainties can be reduced by future observations. We find that the lens cannot be fit by an isolated lens galaxy, but that it can be well fit by including a perturbation from the nearby group of galaxies. To understand the full range of systematic uncertainties, it is crucial to use an ellipsoidal galaxy and to let the group position vary. In this case, the existing constraints cannot break degeneracies in the models with respect to the profiles of the galaxy and group and to the position of the group. Combining the known time delays with a range of lens models incorporating some of the plausible systematic effects yields H0 = 51-13+14 km s-1 Mpc-1. The constraints on the lens models, and hence on H0, can be improved by reducing the standard errors in the lens galaxy position from 50 mas to ∼10 mas, reducing the the uncertainties in the time delays to ∼0.5 days, and constraining the lens mass distribution using Hubble Space Telescope photometry and the fundamental plane. In particular, the time delay ratio rABC = ΔτAC/ΔτBA may provide the best constraint on the mass profile of the galaxy.

Original languageEnglish (US)
Pages (from-to)42-54
Number of pages13
JournalAstrophysical Journal
Volume487
Issue number1 PART I
DOIs
StatePublished - Jan 1 1997

Fingerprint

gravitational lenses
Hubble constant
lenses
galaxies
time lag
perturbation
profiles
mass distribution
Hubble Space Telescope
photometry
alternating current
estimates

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science

Keywords

  • Cosmology: Distance scale
  • Galaxies: Structure
  • Gravitational lensing

Cite this

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abstract = "For the quadruple gravitational lens PG 1115+080, we combine recent measurements of the time delays with new lens models to determine the Hubble constant H0. We explore the effects of systematic uncertainties in the lens models on the estimates of H0, and we discuss how the uncertainties can be reduced by future observations. We find that the lens cannot be fit by an isolated lens galaxy, but that it can be well fit by including a perturbation from the nearby group of galaxies. To understand the full range of systematic uncertainties, it is crucial to use an ellipsoidal galaxy and to let the group position vary. In this case, the existing constraints cannot break degeneracies in the models with respect to the profiles of the galaxy and group and to the position of the group. Combining the known time delays with a range of lens models incorporating some of the plausible systematic effects yields H0 = 51-13+14 km s-1 Mpc-1. The constraints on the lens models, and hence on H0, can be improved by reducing the standard errors in the lens galaxy position from 50 mas to ∼10 mas, reducing the the uncertainties in the time delays to ∼0.5 days, and constraining the lens mass distribution using Hubble Space Telescope photometry and the fundamental plane. In particular, the time delay ratio rABC = ΔτAC/ΔτBA may provide the best constraint on the mass profile of the galaxy.",
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Determining the hubble constant from the gravitational lens PG 1115+080. / Keeton, Charles; Kochanek, C. S.

In: Astrophysical Journal, Vol. 487, No. 1 PART I, 01.01.1997, p. 42-54.

Research output: Contribution to journalArticle

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