Angular Power Spectrum of the Microwave Background Anisotropy Seen by the COBE Differential Microwave Radiometer
Abstract
The angular power spectrum estimator developed by Peebles (1973) and Hauser & Peebles (1973) has been modified and applied to the 2 year maps produced by the COBE DMR. The power spectrum of the real sky has been compared to the power spectra of a large number of simulated random skies produced with noise equal to the observed noise and primordial density fluctuation power spectra of power law form, with $P(k) \propto k^n$. Within the limited range of spatial scales covered by the COBE DMR, corresponding to spherical harmonic indices $3 \leq \ell \lsim 30$, the best fitting value of the spectral index is $n = 1.25^{+0.4}_{-0.45}$ with the Harrison-Zeldovich value $n = 1$ approximately 0.5$\sigma$ below the best fit. For $3 \leq \ell \lsim 19$, the best fit is $n = 1.46^{+0.39}_{-0.44}$. Comparing the COBE DMR $\Delta T/T$ at small $\ell$ to the $\Delta T/T$ at $\ell \approx 50$ from degree scale anisotropy experiments gives a smaller range of acceptable spectral indices which includes $n = 1$.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- December 1994
- DOI:
- 10.1086/174919
- arXiv:
- arXiv:astro-ph/9401015
- Bibcode:
- 1994ApJ...436..443W
- Keywords:
-
- Background Radiation;
- Cosmology;
- Extraterrestrial Radio Waves;
- Microwaves;
- Power Spectra;
- Radio Astronomy;
- Spaceborne Astronomy;
- Universe;
- Anisotropy;
- Computerized Simulation;
- Cosmic Background Explorer Satellite;
- Microwave Radiometers;
- Power Series;
- Random Processes;
- Astronomy;
- COSMOLOGY: COSMIC MICROWAVE BACKGROUND;
- COSMOLOGY: OBSERVATIONS;
- COSMOLOGY: LARGE-SCALE STRUCTURE OF UNIVERSE;
- Astrophysics
- E-Print:
- 22 pages of LaTex using aaspp.sty and epsf.sty with appended Postscript figures, COBE Preprint 94-02