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

Raccanelli, Alvise and Doré, Olivier and Bacon, David J. and Maartens, Roy and Santos, Mario G. and Camera, Stefano and Davis, Tamara and Drinkwater, Michael J. and Jarvis, Matt and 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). Art. No. 042. ISSN 1475-7516.

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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 SKA 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(f_(NL)) ~ 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 f_(NL). Our results show that SKA continuum surveys could provide constraints competitive with CMB and forthcoming optical surveys, potentially allowing a measurement of σ(f_(NL)) ~ 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.

Item Type:Article
Related URLs:
URLURL TypeDescription DOIArticle
Doré, Olivier0000-0002-5009-7563
Santos, Mario G.0000-0003-3892-3073
Jarvis, Matt0000-0001-7039-9078
Norris, Ray0000-0002-4597-1906
Additional Information:© 2015 IOP Publishing Ltd and Sissa Medialab srl. Received October 24, 2014; Accepted December 19, 2014; Published January 30, 2015. AR would like to thank S. Stevanato for useful discussions. Part of the research described in this paper was carried out at the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the National Aeronautics and Space Administration. DJB and RM were supported by the U.K. Science & Technology Facilities Council (grant ST/K0090X/1). RM, MGS and MJ were supported by the South Africa Square Kilometre Array Project and the South African National Research Foundation. MGS and SC acknowledges support from FCT under grant PTDC/FIS-AST/2194/2012. Parts of this research were supported by the Australian Research Council Centre of Excellence in All-sky Astrophysics (CAASTRO), through project number CE110001020.
Funding AgencyGrant Number
Science and Technology Facilities Council (STFC)ST/K0090X/1
South Africa Square Kilometre Array ProjectUNSPECIFIED
National Research Foundation (South Africa)UNSPECIFIED
Fundação para a Ciência e a Tecnologia (FCT)PTDC/FIS-AST/2194/2012
Australian Research CouncilCE110001020
Subject Keywords:power spectrum; cosmological parameters from LSS; integrated Sachs-Wolfe effect; physics of the early universe
Issue or Number:1
Classification Code:PACS: 98.70.Vc; 95.80.+p; 98.62.Py
Record Number:CaltechAUTHORS:20141222-142559397
Persistent URL:
Official Citation:Probing primordial non-Gaussianity via iSW measurements with SKA continuum surveys Alvise Raccanelli et al JCAP01(2015)042
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:53111
Deposited By: Ruth Sustaita
Deposited On:22 Dec 2014 22:41
Last Modified:09 Mar 2020 13:19

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