Can Baryonic Features Produce the Observed 100 H -1 MPC Clustering?


Eisenstein DJ, Hu W, Silk J, Szalay AS. Can Baryonic Features Produce the Observed 100 H -1 MPC Clustering?. The Astrophysical Journal Letters. 1998;494 :L1.

Date Published:

February 1, 1998


We assess the possibility that baryonic acoustic oscillations inadiabatic models may explain the observations of excess power inlarge-scale structure on 100 h-1 Mpc scales. The observed locationrestricts models to two extreme areas of parameter space. In eithercase, the baryon fraction must be large ( Omega b/ Omega0>~0.3 ) in order to yield significant features. The firstregion requires Omega 0<~0.2 h to match the location,implying large blue tilts ( n>~1.4 ) to satisfy cluster abundanceconstraints. The power spectrum also continues to rise toward largerscales in these models. The second region requires Omega 0~1, implying Omega b well out of the range of big bangnucleosynthesis constraints; moreover, the peak is noticeably wider thanthe observations suggest. Testable features of both solutions are thatthey require moderate reionization and thereby generate potentiallyobservable (~1 mu K) large-angle polarization, as well as subarcminutetemperature fluctuations. In short, baryonic features in adiabaticmodels may explain the observed excess only if currently favoreddeterminations of cosmological parameters are in substantial error or ifpresent surveys do not represent a fair sample of 100 h-1 Mpcstructures.