The power spectra of the cosmic microwave background and density fluctuations seeded by local cosmic strings

We compute the power spectra in the cosmic microwave background and cold dark matter (CDM) fluctuations seeded by strings, using the largest string simulations performed so far. We find that local strings differ from global defects in that the scalar components of the stress-energy tensor dominate over vector and tensor components. This result has far reaching consequences. We find that cosmic strings exhibit a single Doppler peak of acceptable height at high . They also seem to have a less severe bias problem than global defects, although the CDM power spectrum in the standard cosmology is the wrong shape to fit large scale structure data.