Elsevier

New Astronomy Reviews

Volume 49, Issues 7–9, November 2005, Pages 360-365
New Astronomy Reviews

Dark energy and cosmic sound

https://doi.org/10.1016/j.newar.2005.08.005Get rights and content

Abstract

I describe how acoustic oscillations imprinted into the late-time correlations of galaxies by baryonic physics at the epoch of recombination can be used as a cosmological standard ruler. Measurements of this length scale by large galaxy surveys would allow us to compute the angular diameter distance to and Hubble parameter at the redshifts of the survey. This in turn offers a robust way to measure the acceleration of the universe. I briefly present calculations of the statistical performance from baseline surveys; full details of the methods and results are available in Seo and Eisenstein [ApJ, 598 (2003) 720]. I discuss the advantages and disadvantages of the acoustic oscillation method relative to other dark energy probes.

Section snippets

General remarks

The unexpected late-time acceleration of the expansion of the universe (Riess et al., 1998, Perlmutter et al., 1999) ranks as one of the top problems in modern cosmology and physics. Sorting between the myriad proposed solutions will require observations of very high precision, as the differences under debate are typically at the percent level (see Fig. 1). The possibility of systematic error, due to the considerable level of precision required, the level of theoretical modeling for

Sound in space?

As this was a meeting on wide-field imaging from space, the question of whether the acoustic oscillation method requires space is apropos. Of course, at many redshifts, imaging (for the purpose of detection and colors, not morphology) and spectroscopy from the ground are straightforward.

However, there are some ways in which a space mission could be of great benefit. Most obviously, the redshift range between 1.4 and 2.0 is spectroscopically challenging from the ground due to the lack of strong

Pros and cons

More generally, it is worth reviewing the advantages and disadvantages of the acoustic oscillation method relative to other methods. First, on the plus side, the acoustic oscillation method is a geometrical large-angle standard ruler test; it is not sensitive to dust or any form of small angle aberration. The ruler itself is based on clean linear-regime physics from the recombination epoch, which is very sensitively probed by the CMB. It is difficult to imagine astrophysical systematic effects

Acknowledgments

D.J.E. thanks Hee-Jong Seo for her collaborations on these topics. D.J.E. is supported by Grant AST-0098577 from the National Science Foundation and by an Alfred P. Sloan Research Fellowship.

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