The elegant theory that underlies gravitational lensing phenomena makes it a powerful tool for exploring the large scale structure of the universe. ELTs bring improved angular resolution and faint source spectroscopy capabilities to gravitational lensing studies which will enble qualitatively new investigations. Probing background sources having more than a decade higher source density than current studies will take weak lensing measurements from the outskirts of individual clusters into the cosmic web. These measurements require imaging and spectroscopy of distant galaxies fainter than m_AB ~ 27 mag (~50 nano-Jansky). Strong gravitational lensing magnifies background sources and will allow the study of individual unresolved sources at least one decade fainter in flux than the telescope will otherwise reach, providing exploratory studies for 100m class telescopes. Strongly lensed sources will allow spectroscopy at sub nano-Jansky source frame flux levels in about 10⁶ seconds. The expected sources include globular clusters in formation and individual first light stars. The geometry of strong lensing will also become a powerful constraint on cosmological constants. In lensed sources it will be possible to measure source frame velocities at about the 500 km s^-1 level. These science goals will require an AO capability in which the PSF shape can be mapped to a precision of 1-2% over a field of about 2 arc-minutes, an integral field-unit spectrograph capable of being deployed on arcs that are generally 10 arc-seconds long and astrometric precision at the level of 10's of micro arc-second.

Date Published: 7 July 2004
PDF: 5 pages
Proc. SPIE 5382, Second Backaskog Workshop on Extremely Large Telescopes, (7 July 2004); doi: 10.1117/12.566084

Published in SPIE Proceedings Vol. 5382:
Second Backaskog Workshop on Extremely Large Telescopes
Arne L. Ardeberg; Torben Andersen, Editor(s)