Determination of inflationary observables by cosmic microwave background anisotropy experiments
- Department of Physics, The University of Chicago, Chicago, Illinois 60637-1433 (United States)
Inflation produces scale-invariant scalar and tensor perturbation spectra which lead to anisotropy in the cosmic microwave background (CMB). The amplitudes and shapes of these spectra can be parametrized by {ital Q}{sub {ital S}}{sup 2}, {ital r}{equivalent_to}{ital Q}{sub {ital T}}{sup 2}/{ital Q}{sub {ital S}}{sup 2}, {ital n}{sub {ital S}}, and {ital n}{sub {ital T}} where {ital Q}{sub {ital S}}{sup 2} and {ital Q}{sub {ital T}}{sup 2} are the scalar and tensor contributions to the square of the CMB quadrupole and {ital n}{sub {ital S}} and {ital n}{sub {ital T}} are the power-law spectral indices. Even if we restrict ourselves to information from angles greater than one-third of a degree, three of these observables can be measured with some precision. The combination 105{sup 1{minus}{ital n}}{sub {ital S}}{ital Q}{sub {ital S}}{sup 2} can be known to better than {plus_minus}0.3%. The scalar index {ital n}{sub {ital S}} can be determined to better than {plus_minus}0.02. The ratio {ital r} can be known to {plus_minus}0.1 for {ital n}{sub {ital S}}{congruent}1 and slightly better for smaller {ital n}{sub {ital S}}. The precision with which {ital n}{sub {ital T}} can be measured depends weakly on {ital n}{sub {ital S}} and strongly on {ital r}. For {ital n}{sub {ital S}}{congruent}1, {ital n}{sub {ital T}} can be determined with a precision of about {plus_minus}0.056(1.5+{ital r})/{ital r}. A full-sky experiment with a 20 arc min beam using technology available today, similar to those being planned by several groups, can achieve the above precision. Good angular resolution is more important than high signal-to-noise ratio; for a given detector sensitivity and observing time a smaller beam provides more information than a larger beam. The uncertainties in {ital n}{sub {ital S}} and {ital r} are roughly proportional to the beam size. We briefly discuss the effects of uncertainty in the Hubble constant, baryon density, cosmological constant, and ionization history.
- OSTI ID:
- 244264
- Journal Information:
- Physical Review, D, Vol. 52, Issue 8; Other Information: PBD: 15 Oct 1995
- Country of Publication:
- United States
- Language:
- English
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