Concordance of kinematics and lensing of elliptical galaxies with WMAP cosmology

H Zhao, B Qin

Research output: Contribution to journalArticlepeer-review

8 Citations (Scopus)

Abstract

We explore degeneracies in strong lensing model so to make time delay data consistent with the WMAP (Wilkinson Microwave Anisotropy Probe) cosmology. Previous models using a singular isothermal lens often yield a time delay between the observed multiple images too small than the observed value if we "hardwire" the now widely quoted post-WMAP "high" value of the Hubble constant (H-0 similar to 71 +/- 4 km s(-1) Mpc(-1)). Alternatively, the lens density profile (star plus dark matter) is required to be locally steeper than r(-2) (isothermal) profile near the Einstein radius (of the order 3 kpc) to fit the time delays; a naive extrapolation of a very steep profile to large radius would imply a lens halo with a scale length of the order only 3 kpc, too compact to be consistent with CDM. We explore more sophisticated, mathematically smooth, positive lens mass density profiles which are consistent with a large halo and the post-WMAP Ho. Thanks to the spherical monopole degeneracy, the "reshuffling" of the mass in a lens model does not affect the quality of the fit to the image positions, amplifications, and image time delays. Even better, unlike the better-known mass sheet degeneracy, the stellar mass-to-light and the Ho value are not affected either. We apply this monopole degeneracy to the quadruple imaged time-delay system PG 1115+080. Finally we discuss the implications of the time delay data on the newly proposed relativistic MOND theory.

Original languageEnglish
Pages (from-to)141-154
Number of pages14
JournalChinese Journal of Astronomy and Astrophysics
Volume6
Issue number2
DOIs
Publication statusPublished - Apr 2006

Keywords

  • cosmological parameters
  • dark matter
  • distance scale
  • gravitational lensing
  • MODIFIED NEWTONIAN DYNAMICS
  • DARK-MATTER
  • GRAVITATIONAL LENSES
  • SCALING RELATIONS
  • DENSITY PROFILE
  • HUBBLE CONSTANT
  • TIME DELAYS
  • PG 1115+080
  • MODELS
  • DEGENERACIES

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