The bispectrum of redshifted 21-cm fluctuations from the dark ages
| dc.creator | Pillepich, Annalisa | |
| dc.creator | Porciani, Cristiano | |
| dc.creator | Matarrese, Sabino | |
| dc.date | 2006-11-03 | |
| dc.date | 2007-03-13 | |
| dc.date.accessioned | 2026-07-07T11:00:06Z | |
| dc.date.available | 2026-07-07T11:00:06Z | |
| dc.description | Brightness-temperature fluctuations in the redshifted 21-cm background from the cosmic dark ages are generated by irregularities in the gas-density distribution and can then be used to determine the statistical properties of density fluctuations in the early Universe. We first derive the most general expansion of brightness-temperature fluctuations up to second order in terms of all the possible sources of spatial fluctuations. We then focus on the three-point statistics and compute the angular bispectrum of brightness-temperature fluctuations generated prior to the epoch of hydrogen reionization. For simplicity, we neglect redshift-space distortions. We find that low-frequency radio experiments with arcmin angular resolution can easily detect non-Gaussianity produced by non-linear gravity with high signal-to-noise ratio. The bispectrum thus provides a unique test of the gravitational instability scenario for structure formation, and can be used to measure the cosmological parameters. Detecting the signature of primordial non-Gaussianity produced during or right after an inflationary period is more challenging but still possible. An ideal experiment limited by cosmic variance only and with an angular resolution of a few arcsec has the potential to detect primordial non-Gaussianity with a non-linearity parameter of f_NL ~ 1. Additional sources of error as weak lensing and an imperfect foreground subtraction could severely hamper the detection of primordial non-Gaussianity which will benefit from the use of optimal estimators combined with tomographic techniques. | |
| dc.description | 15 pages, 4 figures, revised version accepted for publication in ApJ (contains an improved discussion of gas temperature fluctuations) | |
| dc.identifier | https://arxiv.org/abs/astro-ph/0611126 | |
| dc.identifier | http://arxiv.org/abs/astro-ph/0611126 | |
| dc.identifier | Astrophys.J.662:1-14,2007 | |
| dc.identifier | doi:10.1086/517963 | |
| dc.identifier.uri | http://salesiana.dossiersoluciones.com/handle/123456789/187615 | |
| dc.subject | Astrophysics | |
| dc.title | The bispectrum of redshifted 21-cm fluctuations from the dark ages | |
| dc.type | text |