Non-Gaussianity and the CMB bispectrum: Confusion between primordial and lensing-Rees-Sciama contribution?
- Institute of Space Sciences (IEEC-CSIC), Fac. Ciencies, Campus UAB, Bellaterra (Spain)
- Institute of Space Sciences (IEEC-CSIC), Fac. Ciencies, Campus UAB, Bellaterra (Spain) and ICC-UB, Instituto de Ciencias del Cosmos at Universitad de Barcelona, Marti i Franques 1, Barcelona (Spain)
We revisit the predictions for the expected cosmic microwave background bispectrum signal from the cross-correlation of the primary-lensing-Rees-Sciama signal; we point out that it can be a significant contaminant to the bispectrum signal from primordial non-Gaussianity of the local type. This non-Gaussianity, usually parametrized by the non-Gaussian parameter f{sub NL}, arises, for example, in multifield inflation. In particular both signals are frequency-independent, and are maximized for nearly squeezed configurations. While their detailed scale-dependence and harmonic imprints are different for generic bispectrum shapes, we show that, if not included in the modeling, the primary-lensing-Rees-Sciama contribution yields an effective f{sub NL} of 10 when using a bispectrum estimator optimized for local non-Gaussianity. Considering that expected 1-{sigma} errors on f{sub NL} are <10 from forthcoming experiments, we conclude that the contribution from this signal must be included in future constraints on f{sub NL} from the cosmic microwave background bispectrum.
- OSTI ID:
- 21313542
- Journal Information:
- Physical Review. D, Particles Fields, Vol. 80, Issue 12; Other Information: DOI: 10.1103/PhysRevD.80.123007; (c) 2009 The American Physical Society; Country of input: International Atomic Energy Agency (IAEA); ISSN 0556-2821
- Country of Publication:
- United States
- Language:
- English
Similar Records
The full squeezed CMB bispectrum from inflation
The cold spot as a large void: Rees-Sciama effect on CMB power spectrum and bispectrum