AAS 204th Meeting, June 2004
Session 8 UV/Optical Universe at Ultra-High Angular Resolution
Topical Realted Poster, Monday, May 31, 2004, 9:20am-6:30pm, Ballroom

[Previous] | [Session 8] | [Next]

[8.06] Characterizing Dark Energy Through Nano-Arcsecond Astrometry of Quasars

M.J. Pierce (University of Wyoming), W.C. Cash (University of Colorado)

Recent technological developments suggest that space-based interferometry at X-ray wavelengths is feasible. At these wavelengths nano-arcsecond astrometry is be possible with modest, 2-km, baselines. We discuss the prospects for using this capability for high-precision, astrometric measurements of X-ray luminous quasars. The space motion of the Earth with respect to the Cosmic Microwave Background is well characterized and provides an ideal reference frame for such measurements. In particular, it induces a differential parallax for chance alignments of quasars located at different redshifts. We show that the fringes can in principle be measured and that the resulting signal is ideally suited for characterizing the equation of state of dark energy as a function of redshift. The geometric nature of this approach offers a number of advantages over alternative methods. We present a baseline concept for a space-based X-ray interferometer capable of making these measurements and discuss some of the possible technical difficulties with this technique. We also discuss some of the systematic errors with this approach. These include the effects of the transverse peculiar motions of the quasar host galaxies and of gravitational lensing by intervening galaxy halos. We conclude that high-precision astrometry of X-ray luminous quasars offers great promise for characterizing the dark energy content of the universe.

If you would like more information about this abstract, please follow the link to http://www.physics.uwyo.edu/~mpierce/. This link was provided by the author. When you follow it, you will leave the Web site for this meeting; to return, you should use the Back comand on your browser.

[Previous] | [Session 8] | [Next]

Bulletin of the American Astronomical Society, 36 #2
© YEAR. The American Astronomical Soceity.