Issue |
A&A
Volume 541, May 2012
|
|
---|---|---|
Article Number | L4 | |
Number of page(s) | 4 | |
Section | Letters | |
DOI | https://doi.org/10.1051/0004-6361/201219036 | |
Published online | 18 April 2012 |
Quantifying the coherent outflows of galaxies around voids in the SDSS DR7
1 IANIGLA-CONICET, Parque Gral San
Martín, CC 330, 5500 Mendoza,
Argentina
e-mail: spatiri@mendoza-conicet.gob.ar
2 Instituto de Astrofísica de
Canarias, c/ Via Láctea
s/n, 38200
Tenerife,
Spain
3 Departamento de Astrofísica,
Universidad de La Laguna, 38205
Tenerife,
Spain
4 Campus of International Excellence
UAM/CSIC, Cantoblanco, 28049
Madrid,
Spain
5 Instituto de Física Teórica,
UAM/CSIC, Universidad Autónoma de Madrid, Cantoblanco, 28049
Madrid,
Spain
6 Instituto de Astrofísica de
Andalucía (CSIC), Glorieta de la
Astronomía, 18008
Granada,
Spain
Received:
14
February
2012
Accepted:
26
March
2012
We report the detection, with a high level of confidence, of coherent outflows around voids found in the seventh data release of the Sloan Digital Sky Survey (SDSS DR7). In particular, we developed a robust ⟨|cos θ|⟩ statistical test to quantify the strength of redshift-space distortions (RSD) associated with extended coherent velocity fields. We consistently find that the vector that joins void centers with galaxies that lie in shells around them is more likely to be perpendicular to the line-of-sight than parallel to it. This effect is clear evidence for the existence of outflows in the vicinity of voids. We show that the RSD exist for a wide range of void radius and shell thickness, but they are more evident in the largest voids in our sample. For instance, we find that the ⟨|cos θ|⟩ for galaxies located in shells within 2 h-1Mpc from the edge of voids larger than 15 h-1Mpc deviates 3.81σ from uniformity. The measurements presented in this work provide useful information to constrain cosmological parameters, in particular Ωm and σ8.
Key words: cosmology: observations / large-scale structure of Universe / galaxies: statistics / methods: statistical
© ESO, 2012
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