On Variational Dynamics in Redshift Space

Schmoldt, I.; Saha, Prasenjit

doi:10.1086/300383

Cited by 22 publications

(24 citation statements)

References 19 publications

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“…Dynamical studies of the Local Group of ever greater sophistication all conclude that the mass of the Local Group is 4‐‐8×10 12 M ⊙ (e.g. Schmoldt & Saha 1998). If the haloes of M31 and the Milky Way have flat rotation curves with amplitude v c , their masses interior to radius r are given by…”

Section: Discussionmentioning

confidence: 99%

Warps and cosmic infall

Jiang

Binney

1999

Monthly Notices of the Royal Astronomical Society

124

117

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A B S T R A C TN-body simulations show that when infall reorientates the outer parts of a galactic halo by several degrees per Gyr, a self-gravitating disc that is embedded in the halo develops an integral-sign warp that is comparable in amplitude to observed warps. Studies of angularmomentum acquisition suggest that the required rate of halo reorientation is realistic for galaxies like the Milky Way.

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Section: Discussionmentioning

confidence: 99%

Warps and cosmic infall

Jiang

Binney

1999

Monthly Notices of the Royal Astronomical Society

124

117

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“…Minimization of the modified action readily yields the orbits expansion parameters C i,n (see Schmoldt & Saha 1998 for a similar treatment of this problem). The recovered orbits from redshift space depend on V through the f 0 in the expansion (20).…”

Section: Redshift Space Distributionsmentioning

confidence: 99%

On the least action principle in cosmology

Nusser¹,

Branchini²

2000

Monthly Notices of the Royal Astronomical Society

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Given the present distribution of mass tracing objects in an expanding universe, we develop and test a fast method for recovering their past orbits using the least action principle. In this method, termed FAM for fast action minimization, the orbits are expanded in a set of orthogonal time basis functions satisfying the appropriate boundary conditions at the initial and final times. The conjugate gradient method is applied to locate the extremum of the action in the space of the expansion coefficients of the orbits. The treecode gravity solver routine is used for computing the gravitational field appearing in the action and the potential field appearing in the gradient of the action. The time integration of the Lagrangian is done using Gaussian quadratures. FAM allows us to increase the number of galaxies over previous numerical action principle implementations by more than one order of magnitude. For example, orbits for the similar to 15 000 IRAS PSCz galaxies can be recovered in similar to 12 000 CPU seconds on a 400-MHz DEC-Alpha machine. FAM can recover the present peculiar velocities of particles and the initial fluctuations field. It successfully recovers the flow field down to cluster scales, where deviations of the flow from the Zel'dovich solution are significant. We also show how to recover orbits from the present distribution of objects in redshift space by direct minimization of a modified action, without iterating the solution between real and redshift spaces

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“…(12)), as suggested by Schmoldt & Saha (1998). The corresponding dipolar and quadrupolar term may then be based on the best available determinations of these parameters.…”

Section: Inserting External Tidal Potentialmentioning

confidence: 99%

Local supercluster dynamics: external tidal impact of the PSCzsample traced by optimized numerical least action method

Romano-Díaz¹,

Branchini²,

Weygaert³

2005

A&A

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Abstract. We assess the extent to which the flux-limited IRAS PSCz redshift survey encapsulates the complete or major share of matter inhomogeneities responsible for the external tidal forces affecting the peculiar velocity flow within the Local Supercluster and its immediate surroundings. We here investigate this issue on the basis of artificially constructed galaxy catalogs. Two large unconstrained N-body simulations of cosmic structure formation in two different cosmological scenarios form the basis of this study. From these N-body simulations a set of galaxy mock catalogs is selected. From these a variety of datasets is selected imitating the observational conditions of either the local volume-limited Local Supercluster mimicking NBG catalog or the deeper magnitude-limited PSCz catalog. The mildly nonlinear dynamics in the "mock" Local Supercluster and PSCz velocities are analyzed by means of the Least Action Principle technique in its highly optimized implementation of the Fast Action Method. By comparing the velocities in these reconstructions with the "true" velocities of the corresponding galaxy mock catalogs we assess the extent and nature of the external tidal influence on the Local Supercluster volume. We find that the dynamics in the inner 30 h −1 Mpc volume is strongly affected by the external forces. Most of the external forces can be traced back to a depth of no more than 100 h −1 Mpc. This is concluded from the fact that the FAM reconstructions of the 100 h −1 Mpc PSCz volume appear to have included most gravitational influences. In addition, we demonstrate that for all considered cosmological models the bulk flow and shear components of the tidal velocity field generated by the external distribution of PSCz galaxies provides sufficient information for representing the full external tidal force field.

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On Variational Dynamics in Redshift Space

Cited by 22 publications

References 19 publications

Warps and cosmic infall

Warps and cosmic infall

On the least action principle in cosmology

Local supercluster dynamics: external tidal impact of the PSCzsample traced by optimized numerical least action method

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