Bernyk et al. (2014) (MNRAS 2014 on press; astro-ph preprint here) have described a much needed on-line service that I am sure many astronomers will welcome, the Theoretical Astrophysical Observatory (TAO), described as an “on-line an online virtual laboratory that houses mock observations of galaxy survey data.” Visit at https://tao.asvo.org.au/.
Users can produce “mock galaxy mock galaxy catalogues based on selectable combinations of a dark matter simulation, semi analytic galaxy formation models, and stellar population synthesis models.” Generating these mocks are ordinarily difficult because they are computationally demanding and require expert knowledge of the techniques. Now astronomers can use a simple web interface to access cosmological simulations and galaxy-formation models and ship them off to a supercomputer for processing and product creation. Some of the use cases quoted by Bernyk et al. include:
- Making survey predictions and planning observational strategies;
- The comparison of observational data with simulations and models;
- Testing how different physical prescriptions in the same galaxy model affect galaxy evolution;
- The comparison of different galaxy models run on the same dark matter simulation.
The user interface, where astronomers select models and make on-demand processing requests, looks like this:
Underpinning the interface is a modular architecture that takes advantage of the VO Table Access Protocol (TAP) to process queries:
Much of the heavy lifting is performed on the gStar supercomputer at Swinburne University, shown as the box with the black outline. You can see one of the key features of the TAO in the middle of the box: four science modules that support further processing of the data. These modules are:
- Light-cone module. This module remaps the spatial and temporal distribution of galaxies in the original simulation box on to that of the observer light-cone. The parameters of the cone are user configurable.
- Spectral energy distribution module (SED). This module retrieves the star formation and metallicity histories for each galaxy (either in the box or cone) from the TAO database and applies a user-selected stellar population synthesis model and dust model to produce individual galaxy spectra. These spectra are convolved with a set of filters in order to compute both apparent and absolute magnitudes’
- Image module. This module takes the output of both the light-cone and SED modules to construct user defined mock images. Images can be customized using a range of prop-erties, such as sky area, depth, and a selected filter.
Simulation data module. This core module provides direct access to the original simulation and semi-analytic galaxy formation model data stored in the TAO SQL database. The user can specify the desired galaxy and dark matter halo properties to be retrieved at an epoch of interest from the simulation box.
The paper describes several case studies to highlight the applicability of the TAO. See the figure below for two sample products (Figure numbers from original paper):