Chang Refsdal lens

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The Chang-Refsdal lens is a point mass - gravitational lensing caused by a shear term is disturbed.

The name comes from Kyongae Chang and Sjur Refsdal , who published an article in the science journal Nature in 1979 , which described that individual foreground stars can influence the brightness of quasars .

Physical background

This type of gravitational lens represents a model of the effect of a single star in the line of sight of one of the images of a background object (for example, a quasar ) caused by the gravitational lensing effect of a galaxy . Kyongae Chang has shown in her dissertation (1980) that this image can be broken down into up to four sub-images. Due to the very small angular distance, these images cannot be observed directly. However, when the images are created, when the star moves into the line of sight, there can be drastic, characteristic variations in brightness from which information about the mass of the star or the structure of the background object can be obtained. The observation of one or more stars that create this effect is also called the microgravity lensing effect.

See also

literature

  • P. Schneider, J. Ehlers , EE Falco: Gravitational Lenses. Springer, Berlin 1999 ( limited preview in the Google book search).
  • J. Schramm: Stars over Hamburg - The history of astronomy in Hamburg, chapter gravitational lenses. 2nd revised and expanded edition, Kultur- & Geschichtkontor, Hamburg 2010, ISBN 978-3-9811271-8-8 .

Individual evidence

  1. ↑ Kyongae Chang, Sjur Refsdal: Flux Variations of QSO Q0957 + 561 A, B and image splitting by stars Near the Light Path. In: Nature. 282, 1979, pp. 561-564, doi : 10.1038 / 282561a0 .
  2. ↑ Jin H. An, N. Wyn Evans: The Chang-Refsdal lens revisited . In: Monthly Notices of the Royal Astronomical Society . tape 369 , no. 1 , 2006, p. 317–334 , doi : 10.1111 / j.1365-2966.2006.10303.x , bibcode : 2006MNRAS.369..317A .