Reconstruction of cosmological density and velocity fields in the Lagrangian Zel'dovich approximation

Croft, Rupert A. C.; Gaztañaga, E.

doi:10.1093/mnras/285.4.793

Cited by 63 publications

(73 citation statements)

References 24 publications

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“…There is an extensive literature on reconstruction methods for large-scale structure (e.g., Peebles 1989;Weinberg 1992;Nusser and Dekel 1992;Croft and Gaztanaga 1997;Narayanan and Weinberg 1998;Mohayaee et al 2006). Even simple methods appear adequate for BAO recovery, but better reconstruction is valuable for other applications of large-scale structure .…”

Section: Reconstructionmentioning

confidence: 99%

Observational probes of cosmic acceleration

et al. 2013

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The accelerating expansion of the universe is the most surprising cosmological discovery in many decades, implying that the universe is dominated by some form of "dark energy" with exotic physical properties, or that Einstein's theory of gravity breaks down on cosmological scales. The profound implications of cosmic acceleration have inspired ambitious efforts to understand its origin, with experiments that aim to measure the history of expansion and growth of structure with percent-level precision or higher. We review in detail the four most well established methods for making such measurements: Type Ia supernovae, baryon acoustic oscillations (BAO), weak gravitational lensing, and the abundance of galaxy clusters. We pay particular attention to the systematic uncertainties in these techniques and to strategies for controlling them at the level needed to exploit "Stage IV" dark energy facilities such as BigBOSS, LSST, Euclid, and WFIRST. We briefly review a number of other approaches including redshift-space distortions, the Alcock-Paczynski effect, and direct measurements of the Hubble constant H 0 . We present extensive forecasts for constraints on the dark energy equation of state and parameterized deviations from General Relativity, achievable with Stage III and Stage IV experimental programs that incorporate supernovae, BAO, weak lensing, and cosmic microwave background data. We also show the level of precision required for clusters or other methods to provide constraints competitive with those of these fiducial programs. We emphasize the value of a balanced program that employs several of the most powerful methods in combination, both to cross-check systematic uncertainties and to take advantage of complementary information. Surveys to probe cosmic acceleration produce data sets that support a wide range of scientific investigations, and they continue the longstanding astronomical tradition of mapping the universe in ever greater detail over ever larger scales.

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Section: Reconstructionmentioning

confidence: 99%

Observational probes of cosmic acceleration

et al. 2013

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“…The generation of vorticity and velocity dispersion impacts the reconstruction of primordial fluctuations from peculiar velocities [21,22] which assume a cold (single-stream) potential flow, as do other reconstruction methods based on galaxy positions [23,24,25]. The understanding of the nonlinear evolution of the volume weighted (as opposed to mass or galaxy weighted) velocity field is important, since the velocity difference PDF is one of the building blocks that contributes to the redshift space galaxy power spectrum, independent of galaxy bias and calculable from first principles ( [26], see also [27] for recent discussion).…”

Section: Introductionmentioning

confidence: 99%

Generation of vorticity and velocity dispersion by orbit crossing

2009

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We study the generation of vorticity and velocity dispersion by orbit crossing using cosmological numerical simulations, and calculate the backreaction of these effects on the evolution of large-scale density and velocity divergence power spectra. We use Delaunay tessellations to define the velocity field, showing that the power spectra of velocity divergence and vorticity measured in this way are unbiased and have better noise properties than for standard interpolation methods that deal with mass weighted velocities. We show that high resolution simulations are required to recover the correct large-scale vorticity power spectrum, while poor resolution can spuriously amplify its amplitude by more than one order of magnitude. We measure the scalar and vector modes of the stress tensor induced by orbit crossing using an adaptive technique, showing that its vector modes lead, when input into the vorticity evolution equation, to the same vorticity power spectrum obtained from the Delaunay method. We incorporate orbit crossing corrections to the evolution of large scale density and velocity fields in perturbation theory by using the measured stress tensor modes. We find that at large scales (k ≃ 0.1 h Mpc −1 ) vector modes have very little effect in the density power spectrum, while scalar modes (velocity dispersion) can induce percent level corrections at z = 0, particularly in the velocity divergence power spectrum. In addition, we show that the velocity power spectrum is smaller than predicted by linear theory until well into the nonlinear regime, with little contribution from virial velocities.

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“…In the PIZA method of solving the assignment problem (Croft & Gaztañaga 1997), initially a random pairing between N Lagrangian and N Eulerian coordinates is made. Starting from this initial random one-to-one assignment, subsequently a pair (corresponding to two Eulerian and two Lagrangian positions) is chosen at random.…”

Section: Solving the Assignment Problemmentioning

confidence: 99%

Back to the primordial Universe by a Monge–Ampère–Kantorovich optimization scheme

Mohayaee

Frisch

Matarrese

et al. 2003

A&A

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Abstract.A new method for reconstruction of the primordial density fluctuation field is presented. Various previous approaches to this problem rendered non-unique solutions. Here, it is demonstrated that the initial positions of dark matter fluid elements, under the hypothesis that their displacement is the gradient of a convex potential, can be reconstructed uniquely. In our approach, the cosmological reconstruction problem is reformulated as an assignment problem in optimization theory. When tested against numerical simulations, our scheme yields excellent reconstruction on scales larger than a few megaparsecs.

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Reconstruction of cosmological density and velocity fields in the Lagrangian Zel'dovich approximation

Cited by 63 publications

References 24 publications

Observational probes of cosmic acceleration

Observational probes of cosmic acceleration

Generation of vorticity and velocity dispersion by orbit crossing

Back to the primordial Universe by a Monge–Ampère–Kantorovich optimization scheme

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