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In search for the furthest galaxies

teaserAn international research team is performing a program in search for the furthest galaxies in the universe. But distant objects are also very faint. For this reason, the search relies upon one of the strangest implications of general relativity: the amplification of light coming from remote bodies due to the gravitational effects of closer ones, the gravitational lensing effect.


The DAFT/FADA Survey team (leaded by Christophe Adami and with participation of the IAA) has selected almost one hundred very massive galaxy clusters located at moderate distances, with the hope that some of them may be acting as gravitational lenses amplifying the images of galaxies far, far away. Then they study the surroundings of those clusters, by means of many telescopes all around the world, identifying candidates that may count among the furthest galaxies known to date. To this end it is necessary to observe very faint targets that have to be looked at not only in visible light, but also in the infrared. This is due to the cosmological redshift effect, that makes distant galaxies to appear brighter when observed in this “invisible” light, than in the bands accessible to the human eye.


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The surroundings of galaxy cluster GHO 1322+3027 observed with different telescopes and at several spectral bands. The small red circles mark three candidates to be extremely distant galaxies. The infrared image taken at Calar Alto is bottom right.

Recent data have led to several promising candidates, thanks to observations performed at Calar Alto with the 3.5 m Zeiss reflecting telescope and the infrared camera Omega 2000. The results indicate that some targets may be placed really far away (redshift larger tan 6, what means distances larger than ten billion light-years). These results still require additional studies to be fully confirmed, but this on-going research offers an excellent example of what can be reached by means of international cooperation and using in a coordinate way data coming from different observatories.


 

© Calar alto Observatory, February 2013                                               This e-mail address is being protected from spambots. You need JavaScript enabled to view it