Topology of the COBE-DMR First Year Sky Maps

We use the topological genus to test the COBE-DMR first-year sky maps against the hypothesis that the observed temperature fluctuations reflect Gaussian initial density perturbations with random phases. The amplitude of the genus curve reflects the ratio of large- to small-scale power, while the shape tests the Gaussian nature of the temperature distribution. The DMR data are consistent with a Gaussian power law model of initial density perturbations, P(k) ~ k(n) . We use Monte Carlo simulations to fit the DMR data and derive the quadrupole normalization Q_{rms-PS} and the power-law spectral index n. The National Aeronautics and Space Administration/Goddard Space Flight Center (NASA/GSFC) is responsible for the design, development, and operation of the Cosmic Background Explorer (COBE). The COBE program is supported by the Astrophysics Division of NASA's Office of Space Science and Applications.