Daily Image
24-02-2009
Three decades of gravitational lenses
| Submitter: | Olaf Wucknitz |
| Description: | The first gravitational lens Q0957+561 was discovered thirty years ago in 1979. It consists of a radio-loud background quasar that is lensed into two distorted images by a foreground galaxy and its surrounding cluster. To celebrate this anniversary, a gravitational lensing symposium will be held at the JENAM this year. Please register for this event before 9th March at http://www.jenam2009.eu/ . The picture illustrates the discovery from the first Jodrell Bank survey scans (right), showing the source blended with the nearby galaxy NGC3079 (see daily image of 14-04-08 and 05-11-08), the POSS identification (centre, nice handwriting by Meg Urry), through to the resolved optical HST and VLBI imaging (left). The two spectra show the same features at the same redshift, which was the first clear evidence that we see two copies of one and the same object. The background image is a VLA radio map of the system. Today, gravitational lensing has become a very active field in astrophysics, and is used to study all kinds of phenomena from galactic stars and extrasolar planets, to dark matter, dark energy and even cosmology. The idea to use gravitational lenses to measure cosmic distances and the expansion of the universe was first proposed by Sjur Refsdal, back in 1964. We dedicate the meeting to the memory of this most important pioneer of the field who died on 29th January. ASTRON and JIVE have several close lensing links. Mike Garrett was the last PhD student of Dennis Walsh, who discovered the first lens, and who passed away in 2005. Olaf Wucknitz (former JIVE postdoc) was the last PhD student of Sjur Refsdal. Bob Campbell's PhD thesis focused on the milliarcsecond structure of the cores of 0957+561 A,B. A fresh supply of lensing research will be provided by John McKean who recently joined ASTRON's Astronomy Group as a postdoc. A high-resolution version of the poster and more information is available at http://www.astro.uni-bonn.de/~wucknitz/jenam2009/ . |
| Copyright: | You are welcome to distribute this. |
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