Power Spectrum of Cosmic String Perturbations on the Microwave Background
Abstract
I review recent progress towards a detailed understanding of the power spectrum of cosmic string perturbations induced on the Microwave Background (CMB). The use of a simple analytic model allows to include important effects that have not been included in previous studies. These effects are potential fluctuations on the last scattering surface (the SachsWolfe effect) and Doppler CMB perturbations. These previously neglected fluctuations are shown to dominate over postrecombination fluctuations (GottKaiserStebbins effect) on angular scales less than about $2^\circ$ assuming that no reionization occurs. The effective power spectrum index $n_{eff}$ is calculated on COBE scales and is shown to be somewhat larger than 1 ($1.35 \lsim n_{eff} \lsim 1.5$). After normalizing the model on COBE data and string simulations, I derive the predicted values of $({{\delta T}\over T})_{rms}$ for several ongoing CMB experiments on medium and small angular scales. A comparison is also made with current observations and predictions of models based on inflation.
 Publication:

arXiv eprints
 Pub Date:
 June 1994
 arXiv:
 arXiv:astroph/9406020
 Bibcode:
 1994astro.ph..6020P
 Keywords:

 Astrophysics;
 High Energy Physics  Phenomenology
 EPrint:
 Invited Talk at the Global Foundation conference `Unified Symmetry of the Small and the Large', January 2730 1994, Miami, Florida. To appear in the conference proceedings. 18 pages plus 6 figures (available in postscript from the author). Use LaTeX