The 6dF Galaxy Survey: Peculiar velocity field and cosmography

Christopher M. Springob*, Christina Magoulas, Matthew Colless, Jeremy Mould, Pirin Erdoğdu, D. Heath Jones, John R. Lucey, Lachlan Campbell, Christopher J. Fluke

*Corresponding author for this work

    Research output: Contribution to journalArticlepeer-review

    132 Citations (Scopus)

    Abstract

    We derive peculiar velocities for the 6dF Galaxy Survey (6dFGS) and describe the velocity field of the nearby (z < 0.055) Southern hemisphere. The survey comprises 8885 galaxies for which we have previously reported Fundamental Plane data. We obtain peculiar velocity probability distributions for the redshift-space positions of each of these galaxies using a Bayesian approach. Accounting for selection bias, we find that the logarithmic distance uncertainty is 0.11 dex, corresponding to 26 per cent in linear distance. We use adaptive kernel smoothing to map the observed 6dFGS velocity field out to cz ~ 16000 km s-1, and compare this to the predicted velocity fields from the PSCz Survey and the 2MASS Redshift Survey. We find a better fit to the PSCz prediction, although the reduced χ2 for the whole sample is approximately unity for both comparisons. This means that, within the observational uncertainties due to redshift-independent distance errors, observed galaxy velocities and those predicted by the linear approximation from the density field agree. However, we find peculiar velocities that are systematically more positive than model predictions in the direction of the Shapley and Vela superclusters, and systematically more negative than model predictions in the direction of the Pisces-Cetus Supercluster, suggesting contributions from volumes not covered by the models.

    Original languageEnglish
    Pages (from-to)2677-2697
    Number of pages21
    JournalMonthly Notices of the Royal Astronomical Society
    Volume445
    Issue number3
    DOIs
    Publication statusPublished - 5 Sept 2014

    Fingerprint

    Dive into the research topics of 'The 6dF Galaxy Survey: Peculiar velocity field and cosmography'. Together they form a unique fingerprint.

    Cite this