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The Clipped Power Spectrum

The Clipped Power Spectrum. Fergus Simpson University of Edinburgh. FS, James, Heavens, Heymans (2011 PRL) FS, Heavens, Heymans ( arXiv:1306.6349 ). Outline. Introduction to Clipping Part I: The Clipped Bispectrum Part II: The Clipped Power Spectrum. Outline. Introduction to Clipping

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The Clipped Power Spectrum

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  1. The Clipped Power Spectrum Fergus Simpson University of Edinburgh FS, James, Heavens, Heymans (2011 PRL) FS, Heavens, Heymans (arXiv:1306.6349)

  2. Outline • Introduction to Clipping • Part I: The Clipped Bispectrum • Part II: The Clipped Power Spectrum

  3. Outline • Introduction to Clipping • Part I: The Clipped Bispectrum • Part II: The Clipped Power Spectrum

  4. Ripples (easy) Waves (hard)

  5. Accuracy of Perturbation Theory Not only time dependence… …but also spatial dependence:

  6. Local Density Transformations • Reduce nonlinear contributions by suppressing high density regions Neyrinck et al (2009)

  7. Clipping • Typically only 1% of the field is subject to clipping

  8. Outline • Introduction to Clipping • Part I: The Clipped Bispectrum • Part II: The Clipped Power Spectrum

  9. The Bispectrum

  10. The Clipped Bispectrum

  11. The Clipped Bispectrum

  12. The Clipped Bispectrum FS, James, Heavens, Heymans PRL (2011)

  13. Part I Summary • >104 times more triangles available after clipping • Enables precise determination of galaxy bias • BUT • Why does it work to such high k? • What about P(k)?

  14. Outline • Introduction to Clipping • Part I: The Clipped Bispectrum • Part II: The Clipped Power Spectrum

  15. The Power Spectrum

  16. The Clipped Power Spectrum

  17. The Clipped Power Spectrum

  18. Clipped Perturbation Theory • Reduce contributions from by suppressing regions with large

  19. Clipping Part II: The Power Spectrum • Exact solution for a Gaussian Random Field δG: • Exact solution for δ2 :

  20. The Clipped Power Spectrum

  21. The Clipped Power Spectrum

  22. The Clipped Galaxy Power Spectrum

  23. Parameter Constraints FS, Heavens, Heymans arXiv:1306.6349

  24. Part II: Summary • Clipped power spectrum is analytically tractable • Higher order PT terms are suppressed • Nonlinear galaxy bias terms are suppressed • Well approximated by • Applying δmax allows kmax to be increased • ~300 times more Fourier modes available • BUT what happens in redshift space?

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