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C.J. Miller (CMU)
Recently, Eisenstein and Hu (1998) assessed the possibility that baryonic oscillations in adiabatic models may explain observations of excess power in large-scale structure found near the 100h-1Mpc length scale. A ``bump'' (or oscillation) in the power spectrum, can be the result of a non-negligible baryon content of the Universe. Eisenstein and Hu concluded that only two regions of cosmological parameter space fit the data, and both rather poorly. One region requires a high matter density (Omegao ~1), the other a low matter density (Omegao ~0.1). In both cases, the baryon fraction is rather high (fb ~0.35). The high matter density option is ruled out by big bang nucleosynthesis constraints. The low matter density option is much more appealing. Unfortunately, the power spectrum from low Omegao models continues to rise toward larger scales after the k= 0.05hMpc-1 ``bump'', and the data does not support this.
Recently, a number of galaxy and cluster surveys have been published that are large enough to probe the power spectrum beyond k = 0.05hMpc-1. In this report, we combine a number of high-quality cluster and galaxy datasets that trace structure to scales approaching k = 0.009hMpc-1. In these new data, we find that the ``bump'' has shifted slightly towards smaller k and that the power continues to rise on large scales, providing strong support for the detection of baryonic features in a low matter density Universe. We present new constraints on the cosmological parameters that produce the observed features in the power spectrum.
The author(s) of this abstract have provided an email address for comments about the abstract: cmiller3@andrew.cmu.edu