The Gravitational Wave Contribution to Cosmic Microwave Background Anisotropies and the Amplitude of Mass Fluctuations from COBE Results
Abstract
A stochastic background of primordial gravitational waves may substantially contribute, via the SachsWolfe effect, to the largescale cosmic microwave background (CMB) anisotropies recently detected by COBE. This implies a bias in any resulting determination of the primordial amplitude of density fluctuations. We consider the constraints imposed on n < 1 ("tilted") powerlaw fluctuation spectra, taking into account the contribution from both scalar and tensor waves, as predicted by powerlaw inflation. The gravitational wave contribution to CMB anisotropies generally reduces the required rms level of mass fluctuation, thereby increasing the linear bias parameter, even in models where the spectral index is close to the HarrisonZel'dovich value n = 1. This `gravitational wave bias" helps to reconcile the predictions of CDM models with observations on pairwise galaxy velocity dispersion on small scales.
 Publication:

The Astrophysical Journal
 Pub Date:
 December 1992
 DOI:
 10.1086/186668
 arXiv:
 arXiv:hepph/9208214
 Bibcode:
 1992ApJ...401L..49L
 Keywords:

 Anisotropy;
 Cosmic Background Explorer Satellite;
 Cosmology;
 Gravitational Waves;
 Microwaves;
 Relic Radiation;
 Astronomical Models;
 Computational Astrophysics;
 Galactic Evolution;
 Universe;
 Astrophysics;
 COSMOLOGY: COSMIC MICROWAVE BACKGROUND;
 COSMOLOGY: OBSERVATIONS;
 COSMOLOGY: THEORY;
 COSMOLOGY: EARLY UNIVERSE;
 GALAXIES: FORMATION;
 High Energy Physics  Phenomenology
 EPrint:
 11 pages. Two figures available upon request