Probing primordial non-Gaussianity via iSW measurements with SKA continuum surveys

Raccanelli, Alvise, Dore, Olivier, Bacon, David J., Maartens, Roy, Santos, Mario G., Camera, Stefano, Davis, Tamara M., Drinkwater, Michael J., Jarvis, Matt, Norris, Ray and Parkinson, David (2015) Probing primordial non-Gaussianity via iSW measurements with SKA continuum surveys. Journal of Cosmology and Astroparticle Physics, 2015 1: 1-16. doi:10.1088/1475-7516/2015/01/042

Author Raccanelli, Alvise
Dore, Olivier
Bacon, David J.
Maartens, Roy
Santos, Mario G.
Camera, Stefano
Davis, Tamara M.
Drinkwater, Michael J.
Jarvis, Matt
Norris, Ray
Parkinson, David
Title Probing primordial non-Gaussianity via iSW measurements with SKA continuum surveys
Journal name Journal of Cosmology and Astroparticle Physics   Check publisher's open access policy
ISSN 1475-7516
Publication date 2015-01
Sub-type Article (original research)
DOI 10.1088/1475-7516/2015/01/042
Volume 2015
Issue 1
Start page 1
End page 16
Total pages 16
Place of publication Bristol, United Kingdom
Publisher Institute of Physics Publishing
Collection year 2016
Language eng
Formatted abstract
The Planck CMB experiment has delivered the best constraints so far on primordial non-Gaussianity, ruling out early-Universe models of inflation that generate large non-Gaussianity. Although small improvements in the CMB constraints are expected, the next frontier of precision will come from future large-scale surveys of the galaxy distribution. The advantage of such surveys is that they can measure many more modes than the CMB—in particular, forthcoming radio surveys with the Square Kilometre Array will cover huge volumes. Radio continuum surveys deliver the largest volumes, but with the disadvantage of no redshift information. In order to mitigate this, we use two additional observables. First, the integrated Sachs-Wolfe effect—the cross-correlation of the radio number counts with the CMB temperature anisotropies—helps to reduce systematics on the large scales that are sensitive to non-Gaussianity. Second, optical data allows for cross-identification in order to gain some redshift information. We show that, while the single redshift bin case can provide a σ(fNL) ~ 20, and is therefore not competitive with current and future constraints on non-Gaussianity, a tomographic analysis could improve the constraints by an order of magnitude, even with only two redshift bins. A huge improvement is provided by the addition of high-redshift sources, so having cross-ID for high-z galaxies and an even higher-z radio tail is key to enabling very precise measurements of fNL. We use Fisher matrix forecasts to predict the constraining power in the case of no redshift information and the case where cross-ID allows a tomographic analysis, and we show that the constraints do not improve much with 3 or more bins. Our results show that SKA continuum surveys could provide constraints competitive with CMB and forthcoming optical surveys, potentially allowing a measurement of σ(fNL) ~ 1 to be made. Moreover, these measurements would act as a useful check of results obtained with other probes at other redshift ranges with other methods.
Keyword Power spectrum
Cosmological parameters from LSS
Integrated Sachs-Wolfe effect
Physics of the early universe
Q-Index Code C1
Q-Index Status Confirmed Code
Institutional Status UQ

Document type: Journal Article
Sub-type: Article (original research)
Collections: School of Mathematics and Physics
Official 2016 Collection
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