Issue |
A&A
Volume 440, Number 3, September IV 2005
|
|
---|---|---|
Page(s) | 799 - 808 | |
Section | Cosmology (including clusters of galaxies) | |
DOI | https://doi.org/10.1051/0004-6361:20042570 | |
Published online | 05 September 2005 |
Tracing large-scale structure at high redshift with Lyman-α emitters: the effect of peculiar velocities
1
Dipartimento di Astronomia, Università di Trieste, via Tiepolo 11, 34131 Trieste, Italy e-mail: monaco@ts.astro.it
2
European Southern Observatory, Karl-Schwarzschild-Straße 2, 85748 Garching by München, Germany
3
Astronomical Observatory, University of Copenhagen, Juliane Maries Vej 30, 2100 Copenhagen Ø, Denmark
4
University of Aarhus, Ny Munkegade, 8000 Århus C, Denmark
5
European Southern Observatory, Alonso de Córdova 3107, Casilla 19001, Vitacura, Santiago 19, Chile
6
Institute for Computational Cosmology, Department of Physics, University of Durham, South Road, Durham DH1 3LE, UK
7
University of Antwerp, Campus Drie Eiken, Universiteitsplein 1, 2610 Antwerp, Belgium
Received:
17
December
2004
Accepted:
17
May
2005
We investigate the effect of peculiar velocities on the
redshift space distribution of galaxies, and we focus in
particular on Lyα emitters. We generate catalogues of dark
matter (DM) halos and identify emitters with halos of the same
co-moving space density (
). We decompose the peculiar velocity field of
halos into streaming, gradient and random components, and compute and
analyse these as a function of scale. Streaming velocities are
determined by fluctuations on very large scales, strongly affected by
sample variance, but have a modest impact on the interpretation of
observations. Gradient velocities are the most important as they
distort structures in redshift space, changing the thickness and
orientation of sheets and filaments. Random velocities are typically
below or of the same order as the typical observational uncertainty on
the redshift. We discuss the importance of these effects for the
interpretation of data on the large-scale structure as traced by
Lyα emitters (or similar kinds of astrophysical high-redshift
objects), focusing on the induced errors in the viewing angles of
filaments. We compare our predictions of velocity patterns
for Lyα emitters to observations and find that redshift clumping of Lyα emitters, as reported for instance in
the fields of high-redshift radio galaxies, does not allow to infer whether
an observed field is sampling an early galaxy overdensity.
Key words: cosmology: theory / cosmological parameters
© ESO, 2005
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