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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 language | English |
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Pages (from-to) | 141-154 |
Number of pages | 14 |
Journal | Chinese Journal of Astronomy and Astrophysics |
Volume | 6 |
Issue number | 2 |
DOIs | |
Publication status | Published - 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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Dive into the research topics of 'Concordance of kinematics and lensing of elliptical galaxies with WMAP cosmology'. Together they form a unique fingerprint.Projects
- 1 Finished
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Astrophysics at St Andrews: Astrophysics at St.Andrews
Cameron, A. C. (PI) & Horne, K. D. (CoI)
1/04/06 → 31/03/11
Project: Standard