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The galaxy power spectrum on the lightcone etc.pdf (2.45 MB)

The galaxy power spectrum on the lightcone: deep, wide-angle redshift surveys and the turnover scale

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posted on 2023-06-10, 05:03 authored by Daniel Pryer, Robert E SmithRobert E Smith, Robin Booth, Chris Blake, Alexander Eggemeier, Jonathan LovedayJonathan Loveday
We derive expressions for the survey-window convolved galaxy power spectrum in real space for a full sky and deep redshift survey, but taking into account the geometrical lightcone effect. We investigate the impact of using the standard mean redshift approximation as a function of survey depth, and show that this assumption can lead to both an overall amplitude suppression and scale-dependent error when compared to the 'true' spectrum. However, we also show that by using a carefully chosen 'effective fixed-time', one can find a range of scales where the approximation to the full model is highly accurate, but only on a more restricted set of scales. We validate the theory by constructing dark matter and galaxy lightcone mock surveys from a large N-body simulation with a high cadence of snapshots. We do this by solving the light cone equation exactly for every particle, where the particle worldlines are obtained in a piecewise fashion with cubic interpolation between neighbouring snapshots. We find excellent agreement between our measurements and the theory (~ ±5%) over scales (0.004 h Mpc-1 = k = 0.54 h Mpc-1) and for a variety of magnitude limits. Finally, we look to see how accurately we can measure the turnover scale of the galaxy power spectrum k 0. Using the lightcone mocks we show that one can detect the turnover scale with a probability P = 95% in an all-sky catalogue limited to an apparent magnitude m lim ~ 21. We also show that the detection significance would remain high for surveys with m lim ~ 22 and 20% sky coverage.


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Journal of Cosmology and Astroparticle Physics




IOP Publishing



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This is the Accepted Manuscript version of an article accepted for publication in Journal of Cosmology and Astroparticle Physics.?IOP Publishing Ltd is not responsible for any errors or omissions in this version of the manuscript or any version derived from it.?The Version of Record is available online at

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