Cosmic Microwave Background and Density Fluctuations from Strings plus Inflation

In cosmological models where local cosmic strings are formed at the end of a period of inflation, the perturbations are seeded both by the defects and by the quantum fluctuations, with similar amplitudes. In a flat cosmology with zero cosmological constant and 5% baryonic component, strings plus inflation fit the observational data much better than each component individually. The large-angle cosmic microwave background spectrum is mildly tilted, for Harrison-Zeldovich inflationary fluctuations. It then rises to a thick Doppler bump, covering $\ell =200\mathrm{}–600$, modulated by soft secondary undulations. The standard cold dark matter antibiasing problem is cured.