Data Guide | Available Data Sets

N-body Simulations and Semi-Analytic Models

Here we list the base N-body simulations upon which the semi-analytic galaxies in TAO are built. Further information on each simulation is provided in their respective pages, as linked. For each simulation, we list the semi-analytic models that have been used to fill their haloes with galaxies. Each of these is also linked to a page with further information. In most cases, these simulation–model pairings are confined to box (snapshot) and light-cone data products. Pre-made catalogues exist for some of these as well as models not listed here (see below).

Survey / Telescope Presets

TAO offers the user access to pre-configured data sets that match the approximate redshift range, footprint, and basic galaxy properties of a number of current popular galaxy surveys. This is an easy way to create a basic mock catalogue for one of these surveys. The parameters of each can be modified before submitting, allowing further customisation.

Premade Catalogues

This option allows you to download pre-constructed mock catalogues. Such mocks may have been previously built for a specific purpose and/or include features or properties that TAO cannot currently produce itself. These cannot be modified (to do that we recommend you create a new galaxy catalogue), however you can sub-select from the premade catalogue property list, and make additional property cuts (e.g. taking a higher mass or magnitude limit).

Redshift Zero Catalogues from Croton et al. 2006

These mocks are the same as those used in Croton et al. 2006 and run on the Millennium Simulation box, output at z=0.

• BVRIK(Cousins) or ugriz(SDSS) filter sets are included (Vega).
• Catalogues are provided for the full simulation box and the mini-Millennium Run box (same but 1/512 the size, optimised for testing).
• Each full catalogue contains approximately 9 million galaxies down to a limiting absolute magnitude of M_B-5logh = -15.6 or M_r-5logh = -16.6.
• The following redshift zero information is available for each galaxy:
• position and velocity
• total and bulge magnitudes in 5 bands (BVRIK or ugriz)
• total and bulge stellar mass
• cold, hot and ejected gas mass
• black hole mass
• star formation rate

Survey Light-Cones from Croton et al. 2006

These cones were built using the original Croton et al. 2006 semi-analytic model, with the addition of the dust prescription given in Kitzbichler & White 2007. They were constructed by taking lines-of-sight through the Millennium Simulation halo and galaxy catalogue box at increasing redshifts, using code written by Manfred Kitzbichler and described in Kitzbichler & White 2007.

Three sets of light-cones are available, differing primarily in their magnitude limits, redshift depth, and sky coverage. Common to all cones are the following fields:

• galaxy type (central or satellite)
• galaxy/halo position and velocity
• halo virial properties (Mvir, Vvir, Rvir)
• halo spin and velocity dispersion
• total and bulge stellar mass
• cold, hot and ejected gas mass
• black hole mass
• star formation rate
• hot halo cooling and AGN heating rates
• apparent and absolute (total and bulge) magnitudes in DEEP2 (BRIK), SDSS (ugriz), and Cousins (BVRIK) filters, for each galaxy (14 filters in all)

Note that:

• All magnitudes are in the AB system.
• Absolute magnitudes for DEEP2 and SDSS filters were calculated from the apparent magnitudes using the appropriate version of Mike Blanton's k-correct. For some cones the k-corrections may not be valid across the entire redshift range. In such cases, please use the Cousins absolute magnitudes or do your own k-corrections from the apparent magnitudes.

CANDELS Light-Cones from z=0 to z=10

These premade catalogues are a preliminary set of cones built for the CANDELS Team, matched to the 5 different survey fields of interest for CANDELS science, extending up to redshift 10 and cut at WFC3/F160W < 28.0. Three different semi-analytic galaxy models are provided for each field, each built using the same set of halo merger trees extracted from the Bolshoi Simulation. Many different filters and galaxy/halo properties are available, making the full cone data somewhat unwieldy in size. Accessed through TAO, each cone can be sub-selected to only include the properties of interest, making the data footprint much more manageable.

More information on the models can be found here. In particular, a full summary of the model recipes and parameter values can be found here. The following table provides a list of model and field combinations on offer:

Quasar Mocks from z=0 to z=4.89

These quasar mocks were constructed on the merger trees of the Millennium Simulation using the analytic method described in “A simple model to link the properties of quasars to the properties of dark matter halos out to high redshift" (Croton 2009. MNRAS, 394, 1109).

They were constrained to have the correct quasar luminosity function and mBH-σ relation from low to high redshift. They also reproduce many other fundamental quasar statistics, such as the observed quasar clustering and lifetimes. Catalogues include the entire halo mass function at each redshift (i.e. halos both with and without quasars) so that lifetimes, HODs, etc can be calculated. A flag is included for each object indicating whether the model has marked it as an active quasar or not.

There are 16 model+simulation outputs provided in total, covering redshifts up to z=4.89. The following information is available for each object:

• quasar absolute magnitude
• black hole mass
• host halo virial mass and velocity
• quasar/halo position in real and redshift space

Durham Millennium-XXL Mock Light-Cones

Two premade Light-Cones exist using data from the Millennium-XXL simulation data on TAO. These are detailed in the paper by Smith et al. (2017). The "Halo Catalogue" extends out to z=2.2 and includes the following properties from the simulation:

• halo virial properties (Mvir, Vvir, Rvir)
• halo velocity dispersion
• right ascension and declination
• observed and cosmological redshift

The "Galaxy Catalogue" has been built by applying a Halo Occupation Distribution model to the simulation. This extends to z=0.8 and includes the following galaxy/halo properties:

• absolute and apparent SDSS r-band magnitudes
• g - r colour
• halo mass
• right ascension and declination
• observed and cosmological redshift

Meraxes/Tiamat Galaxy Catalogue

Meraxes (Mutch et al. 2016) has been built as part of the Dark-ages Galaxy Observables from Numerical Simulations (DRAGONS) programme. It is the first semi-analytic galaxy formation model to possess a full temporal and spatial coupling between the ionization state of the IGM during the Epoch of Reionization and the growth of galaxies.

Meraxes has been run on the Tiamat N-body simulation (Poole et al. 2016), which was also developed as part of the DRAGONS programme.