Hubble Volume Mock 2dF, 6dF, PSCz and SDSS Galaxy Redshift Catalogues

Hubble Volume Mock APM, 2dF,6dF, PSCz and SDSS

by Shaun Cole, Carlton Baugh, Enzo Branchini, Steve Hatton and the VIRGO consortium

The mock catalogues which are available here are extracted from the 1 billion particle N-body simulations performed by the VIRGO consortium of volumes approaching the size of the entire Hubble Volume.

If you make use of Hubble Volume data downloaded from this site please let us know by dropping a short email to Prof . Please acknowledge both the Durham astrophysics theory group and the VIRGO consortium in any papers you produce that make use of these mock catalogues.

The methods of generating the mock catalogues is the same as for the original published mock catalogues (Cole etal MNRAS 1998 300, 945) . The only biasing scheme that was utilised is bias model 2, which is a 2-parameter model based on the final density field. These catalogues have been stored as (gzipped) ASCII files and hopefully their content needs little explanation.

Three different sets of Hubble Volume mock catalogues are available in the following three directories:

  • LambdaCDM03 which date from June 2002
  • LambdaCDM04 which date from december 2003 and are the catalogues used in the analysis of the Cole etal 2005 2dFGRS power spectrum analysis. They differ from the LambdaCDM03 in just two minor ways. The k+e correction used in the selection was tweaked and so were the bias parameters.
  • LambdaCDM04r which differ from the previous in that the observers were placed at random rather that locations picked to fit Local Group constraints.

    See the information described and linked below for details.

    Mock APM, 2dF, PSCz and 6dF catalogues

    This set all have "Local Group" observers and the position and orientation of the observer is the same in the corresponding APM, 2dF, 6dF and PSCz catalogues.

    The advantages

    1. The large volume of the simulation box (L= 2000 Mpc/h for TauCDM) means that long wavelengths are well represented and many essentially independent APM, 2dF, 6dF, PSCz or SDSS volumes can be drawn from a single simulation.
    2. We have used a more realistic k+e correction for the model galaxies and tuned the bias parameters and luminosity function to produce a selection function and clustering that is a reasonable match to that of the genuine galaxy redshift survey data.
    3. We have not chosen the observer at random but instead selected only observers which satisfy a certain set of constraints which effectively make the observer live in a region with similar properties to the Local Group.
    4. Rather than generating the 2dF SGP catalogue we have generated a larger catalogue covering the full area of the published APM catalogue down to a magnitude of Bj=20.5 . Also the NGP region has been extended over a larger delcination range than will be targetted in the 2dF redshift survey. Software to extract the precise 2dF regions from this is available. Note that it is an idealised catalogue and we have the software to cut out the holes around bright stars etc in the genuine catalogue.
    5. We have generated one catalogue with the selection characteristics of the full SDSS photometric catalogue. The Hubble Volume simulation is the only one large enough to make this feasible.

    The disadvantages

    1. We do not have a wide range of different cosmological models. At present there is just a TauCDM model and a LambdaCDM model. Nor do we have a range of different biasing schemes. Thus these catalogues are not as useful as the original set for testing the robustness of analysis techniques.
    2. The mass resolution is slightly poorer than in the orginals. The mean particle seperation is 2 Mpc/h as opposed to 1.8 Mpc/h .