SCIENCE WITH A LMT : INTRODUCTION
Given the unique capability of Liquid Mirror Telescopes (hereafter LMTs) which can be entirely dedicated to specific observational projects, also considering their very low cost (~ 2 millions € for a 4m LMT) but because of their apparently restricted field of view (~0.5°), it was felt important to gather members from the astronomical community at large to discuss all potential astrophysical and cosmological applications using such telescopes. To fulfill this goal, a workshop entitled 'Science with Liquid Mirror Telescopes' has been organized at the Observatory of Marseille on April 14-15, 1997. Approximately 25 scientists from all over the world have participated to this meeting. At the end of the workshop, a general consensus had emerged about the need for constructing and operating a 4 m LMT in a good astronomical site in order to achieve several dedicated projects of great scientific interest. A detailed account of the main science drivers that could justify building a LMT as an astronomical research instrument may be found here (lien vers le proceeding).
LMT's can only observe the Zenith. Consequently, a LMT continuously monitors the strip of sky passing through the Zenith
. The telescope scans a strip of constant declination equal to the latitude of the observatory. Such a strip of constant declination moves in and out of the galactic plane.
Because a LMT observes the same region of the sky night after night
, it is possible to:
- co-add the images taken on different nights in order to improve the limiting magnitude attainable with a LMT;
subtract images taken on different nights to make a variability study of the corresponding strip of sky.
So a LMT is a unique instrument which can be entirely dedicated to the photometric and astrometric survey of a narrow band of the sky
. Most of the potential applications of LMTs come from the possibility of making time dependent photometric light curves of all the objects in the band of sky and its ability to discover objects with variable flux and/or position.
A short list of the science drivers of LMTs is presented in the next section
SCIENCE DRIVERS WITH LMTs :
QUASARS AND GRAVITATIONAL LENSES :
- search for quasars and multiple imaged quasars induced by gravitational lensing,
- statistical determination of the cosmological parameters H0, q0 and Lambda0 based upon surveys for multiply imaged quasars, if the mass distribution in the lens is sufficiently well modeled,
- determination of the mass distribution in the lensing galaxies adopting the value of H0 as derived from independent techniques.
SUPERNOVAE DETECTION :
- search for supernovae,
- statistical determination of the cosmological parameters H0, q0 and Lambda0 based upon surveys for supernovae,
- search for faint extended objects such as galactic nebulae, supernovae remnants, ...
OTHER SCIENTIFIC TOPICS :
- trigonometric parallaxes of faint nearby objects (e.g. brown dwarfs, ...),
- observational studies of large scale structures,
- detection of high stellar proper motions to probe a new range of small scale kinematics (stars, trans-neptunian objects, ...),
- astrometry of multiple star systems,
- a wide range of photometric variability studies (cf. photometry of stars, RR Lyrae, micro-lensing effects, photometry of variable AGN over day to year time scales, ...)
- search for low surface brightness and star-forming galaxies,
- galaxy clustering and evolution,
- serendipitous phenomena,
- and, finally, production of a unique database for follow up studies with the VLT, Gemini, SALT and other 8-10m class telescopes.