Abstract: (arXiv)
We describe the BOOMERanG experiment and its main result, i.e. the measurement of the large scale curvature of the Universe. BOOMERanG is a balloon-borne microwave telescope with sensitive cryogenic detectors. BOOMERanG has measured the angular distribution of the Cosmic Microwave Background on 3\sim 3% of the sky, with a resolution of 10\sim 10 arcmin and a sensitivity of 20μK\sim 20 \mu K per pixel. The resulting image is dominated by hot and cold spots with rms fluctuations 80μK\sim 80 \mu K and typical size of 1o\sim 1^o. The detailed angular power spectrum of the image features three peaks and two dips at =(21313+10),(54132+20),(84525+12)\ell = (213^{+10}_{-13}), (541^{+20}_{-32}), (845^{+12}_{-25}) and =(41612+22),(750750+20)\ell = (416^{+22}_{-12}), (750^{+20}_{-750}), respectively. Such very characteristic spectrum can be explained assuming that the detected structures are the result of acoustic oscillations in the primeval plasma. In this framework, the measured pattern constrains the density parameter Ω\Omega to be 0.85<Ω<1.10.85 < \Omega < 1.1 (95% confidence interval). Other cosmological parameters, like the spectral index of initial density fluctuations, the density parameter for baryons, dark matter and dark energy, are detected or constrained by the BOOMERanG measurements and by other recent CMB anisotropy experiments. When combined with other cosmological observations, these results depict a new, consistent, cosmological scenario.
Note:
  • Proc. of the Erice School on Neutrinos in Astro, Particle and Nuclear Physics, 18.-26. September 2001, Amand Faessler, Jan Kuckei eds, Progress in Particle and Nuclear Physics, vol. 48