Astrophysics

Balloon Mapping of a Flat Universe

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Science  05 Jan 2001:
Vol. 291, Issue 5501, pp. 17
DOI: 10.1126/science.291.5501.17a

Spatial fluctuations in the cosmic microwave background (CMB) radiation represent weak temperature anomalies produced right after the Big Bang as large-scale structure started to form in the universe. Measuring the CMB is difficult because the signal is weak and can be contaminated by Earth's atmosphere and other astrophysical foregrounds. Recent studies with the COBE satellite and the BOOMERANG balloon experiment in Antarctica have produced useful maps of the CMB temperature fluctuations.

Now, Hanany et al. have generated a map and power spectrum of CMB anisotropy using the MAXIMA-1 Balloon experiment which was launched from Palestine, Texas. The MAXIMA-1 results provide improved sensitivity and a broader range of angular scales than previous observations. A companion paper by Balbi et al. discusses the cosmological implications. The MAXIMA-1 CMB map and spectrum indicate a flat universe and strongly constrain the relative level of primordial density fluctuations between different angular scales; these results are consistent with predictions of a period of inflationary growth of the universe shortly after the Big Bang. An inventory of the energy in the universe and amounts of cold dark matter and ordinary matter (baryons) are also derived from these observations and analyzed together with results from recent supernova type I-A measurements. — LR

Astrophys. J.545, L5 (2000); Astrophys. J.545, L1 (2000).

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