Galaxy and Mass Assembly (GAMA): Redshift Space Distortions from the Clipped Galaxy Field

Simpson, F and Blake, C and Peacock, JA and Baldry, IK and Bland-Hawthorn, J and Heavens, A and Heymans, C and Loveday, J and Norberg, P (2016) Galaxy and Mass Assembly (GAMA): Redshift Space Distortions from the Clipped Galaxy Field. Physical Review D, 93. ISSN 1550-2368

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Abstract

We present the first cosmological measurement derived from a galaxy density field subject to a `clipping' transformation. By enforcing an upper bound on the galaxy number density field in the Galaxy and Mass Assembly survey (GAMA), contributions from the nonlinear processes of virialisation and galaxy bias are greatly reduced. This leads to a galaxy power spectrum which is easier to model, without calibration from numerical simulations. We develop a theoretical model for the power spectrum of a clipped field in redshift space, which is exact for the case of anisotropic Gaussian fields. Clipping is found to extend the applicability of the conventional Kaiser prescription by more than a factor of three in wavenumber, or a factor of thirty in terms of the number of Fourier modes. By modelling the galaxy power spectrum on scales k < 0.3 h/Mpc and density fluctuations $\delta_g < 4$ we measure the normalised growth rate $f\sigma_8(z = 0.18) = 0.29 \pm 0.10$.

Item Type: Article astro-ph.CO; astro-ph.CO Q Science > QB Astronomy Astrophysics Research Institute American Physical Society Author 19 Jan 2016 14:27 23 Mar 2016 13:01 http://researchonline.ljmu.ac.uk/id/eprint/2680