Multiple-streaming and the probability distribution of density in redshift space
Jan, 199923 pages
Published in:
- Astrophys.J. 537 (2000) 12-20
e-Print:
- astro-ph/9901104 [astro-ph]
DOI:
Report number:
- FERMILAB-PUB-99-004-A
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Abstract: (arXiv)
We examine several aspects of redshift distortions by expressing the redshift-space density in terms of the eigenvalues and orientation of the local Lagrangian deformation tensor. We explore the importance of multiple-streaming using the Zel'dovich approximation (ZA), and compute the average number of streams in real and redshift-space. It is found that multiple-streaming can be significant in redshift-space but negligible in real-space, even at moderate values of the linear fluctuation amplitude (). Moreover, unlike their real-space counter-parts, redshift-space multiple-streams can flow past each other with minimal interactions. Such nonlinear redshift-space effects, which operate even when the real-space density field is quite linear, could suppress the classic compression of redshift-structures predicted by linear theory (Kaiser 1987). We also compute using the ZA the probability distribution function (PDF) of density, as well as , in real and redshift-space, and compare it with the PDF measured from N-body simulations. The role of caustics in defining the character of the high density tail is examined. It is found that (non-Lagrangian) smoothing, due to both finite resolution or discreteness and small-scale velocity dispersions, is very effective in erasing caustic structures, unless the initial power spectrum is sufficiently truncated.Note:
- 23 pages, 5 ps figures, submitted to ApJ Report-no: FERMILAB-Pub-99/004-A, CITA-99-1 Journal-ref: Astrophys.J. 537 (2000) 12-20
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