Intensity Mapping with the SKA

Intensity mapping with the SKA

Phil Bull arXiv:1405.1452 University of Oslo SKA

Low-freq. aperture array Very cheap, large field of view Electronic beam forming SKA1-LOW

Mid-freq. aperture array Cheap, large field of view Electronic beam forming

Dish arrays ~96-250 steerable dishes Interferometer with dense core Baselines from 20m – 100km SKA1-MID, SKA1-SUR KAT 7 7 x 12m dishes S. African site It's alive!

MeerKAT S. African site 64 x 13.5m dishes Choice of two bands for HI

ASKAP 36 x 12m dishes 36-element PAFs W. Australia (MRO)

Square Kilometre Array

● Large frequency range

● Gigantic collecting area

● Broad range of angular resolutions

● 2018 – 2023: Phase 1 construction

● First science from 2020 (c.f. Euclid)

● More propaganda at www.skatelescope.org

Forecasts

Fisher formalism

● Fisher matrix:

● Signal covariance:

● Redshift-space power spectrum:

Fisher formalism

● Noise covariance:

● Residual foregrounds:

Interferometer vs. dish survey

15m dishes, 25,000 sq. deg survey

~ BINGO

~ MeerKAT/ASKAP

~ SKA1

~ Euclid/LSST

Power Spectrum

Distance measures

Dark Energy

Curvature

● Curvature is a strong prediction of inflation

● Eternal inflation would be ruled-out if curvature was detected above the |10-4| level (Kleban & Schillo, Guth & Nomura)

-4 ● Fundamental limit of detectability at ~|10 | too (Vardanyan et al. 2009, PB & Kamionkowski 2013)

Kleban & Schillo (2012)

Curvature

Modified gravity

Marginal constraints

USPs

Competition

● Galaxy redshift survey always wins! (for same volume)

● IM can never exactly match CV-limited redshift survey

● Foregrounds

● Resolution effects

Ultra-large scales

SKA-SUR Full (Band 1)

Non-Gaussianity

● Scale-dependent bias at small k

● SKA should be able to measure σ(fNL) ~ 1

fNL = 10

Camera et al. (2013) Redshift range

Summary

● SKA is not purpose-designed for IM

● SKA 21cm survey will compete with Euclid, LSST IF we can use autocorrelation data

● It will also complement galaxy redshift surveys

● We can also do things that optical surveys can't