Degeneracies of the radial mass profile in lens models
ADS bibcode 2001glrp.conf..157W
astro-ph/9909291
ASP Conference Series Vol. 237 (2001)
Gravitational Lensing: Recent Progress and Future Goals
editors: T.G. Brainerd and C.S. Kochanek
O. Wucknitz [1], S. Refsdal [1]
- Hamburger Sternwarte, Gojenbergsweg 112, D-21029 Hamburg, Germany
Abstract
Original Poster
We discuss a simple parameter degeneracy in lens models which follows
directly from the well known mass sheet degeneracy. A spherical power
law model with external shear can be transformed into an equivalent
scaled model with an additional mass sheet. This transformation
effectively changes the mass index of the radial density distribution.
Wambsganss and Paczynski (1994) have found this degeneracy for
numerical models of 2237+0305 before.
Proceedings version
We discuss a simple parameter degeneracy in lens models which
follows directly from the well known mass sheet degeneracy and
prevents determining the radial mass distribution from lensing alone
for many systems. For cosmological important systems like 1115+080
it is shown that no exact value of H0 can be determined without
assuming a mass index.
Erratum
Embarrassingly, I have to withdraw the last section of the original poster version about elliptical models. The assumed deflection angle does not correspond to a physical mass distribution. This invalidates the results for elliptical models. The scaling behaviour for them is different from the spherical + shear models as I will show in an upcoming paper. This does not affect the proceedings version.
ADS bibcode 2001glrp.conf..157W (link to ADS entry)
proceedings version:
astro-ph/9909291 (link to e-print archive)
download original poster version
gzipped postscript file (162.5 kB, last change 13 Sep 1999)
unzipped postscript file (505.4 kB)
(see erratum above)
download proceedings version
gzipped postscript file (26.5 kB, last change 27 Oct 1999)
unzipped postscript file (60.1 kB)
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