LensClean revisited
DOI: 10.1111/j.1365-2966.2004.07513.x (http) or 10.1111/j.1365-2966.2004.07513.x (doi)
ADS bibcode 2004MNRAS.349....1W
astro-ph/0312262
O. Wucknitz [1,2,3]
- University of Manchester, Jodrell Bank Observatory, Macclesfield, Cheshire SK11 9DL, UK
- Hamburger Sternwarte, Universität Hamburg, Gojenbergsweg 112, 21029 Hamburg, Germany
- Universität Potsdam, Institut für Physik, Am Neuen Palais 10,14469 Potsdam, Germany
Abstract
We discuss the LensClean algorithm which for a given gravitational lens model fits
a source
brightness distribution to interferometric radio data in a similar way as
standard Clean does in the unlensed case. The lens model
parameters can then be varied in order to minimize the residuals and determine
the best model for the lens mass distribution.
Our variant of this method is improved in order to be useful and stable
even for high dynamic range systems with nearly degenerated lens model
parameters. Our test case B0218+357 is dominated by two bright images but the
information needed to constrain the unknown parameters is
provided only by the
relatively smooth and weak Einstein ring. The new variant of LensClean is able to
fit lens models even in this difficult case.
In order to allow the use of general mass models with LensClean, we develop the new
method LenTil which inverts the lens equation much more reliably
than any other method. This high reliability is essential for the use as part
of LensClean.
Finally a new method is developed to produce source plane maps of the unlensed
source from the best LensClean brightness models. This method is based on the new
concept of "dirty beams" in the source plane.
The application to the lens B0218+357 leads to the first useful constraints for
the lens position and thus to a result for the Hubble
constant. These results are presented in an accompanying Paper II, together with
a discussion of classical lens modelling for this system.
Key words:
gravitational lensing -- techniques: interferometric -- methods: data analysis -- quasars: individual: JVAS B0218+357
This is the first of two papers about our new variant of LensClean (this Paper I) and its application to the lens B0218+357 (Paper II). This work was initially submitted in January 2003 as a single paper.
For more details, have a look at my PhD thesis.
MNRAS 349 (2004) 1-13 (link to online journal)
DOI (Digital Object Identifier): 10.1111/j.1365-2966.2004.07513.x (http) or 10.1111/j.1365-2966.2004.07513.x (doi)
ADS bibcode 2004MNRAS.349....1W (link to ADS entry)
astro-ph/0312262 (link to e-print archive)
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13 pages, b/w.
This is an electronic version of an article published in Monthly Notices of the Royal Astronomical Society: complete citation information for the final version of the paper, as published in the print edition of Monthly Notices of the Royal Astronomical Society, is available on the Blackwell Synergy online delivery service, accessible via the journal's website at http://www.blackwellpublishing.com/journals/MNR or http://www.blackwell-synergy.com
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