Technical Guide | Overview

The Theoretical Astrophysical Observatory (TAO) provides web access to cloud-based mock extragalactic survey data, generated using sophisticated semi-analytic galaxy formation models that are coupled to large N-body cosmological simulations. TAO is designed to be flexible, so that different simulations and galaxy formation models can be stored and accessed from a single location with a consistent data format. The interface for TAO is clean and built with simplicity in mind. In the spirit of reaching as many astronomers as possible, the user interface design objective is to provide a simple portal that makes using the science modules easy and intuitive. No programming knowledge (SQL or other) is required to use any part of TAO, maximizing accessibility to astronomers, be they observers or theorists.

A major feature of TAO is its ability to post-process the hosted data for different scientific applications. This is achieved through a number of science modules that can be linked in user-specified configurations, depending on the desired requirements of the astronomer and the module functionality. In addition, this modular design makes TAO readily expandable with new functionality in the future. TAO is part of the larger All-Sky Virtual Observatory (ASVO) project, whose goal is to federate and distribute astronomical data to the wider community via a cloud-based data storage system. The ASVO constitutes a major infrastructure investment that links observational data with theoretical capabilities. It establishes a platform from which astronomers can optimally access and exploit the exponential growth in astronomical data volume in the coming decade.

In the sections below we describe the components of TAO and give an overview of how they work. The main data requirements are also introduced.

• The TAO Infrastructure
• An Overview: A brief summary of how TAO is organised "under the hood".
• The TAO Core and Scientific Modules
• Light Cone Module: This module remaps the spatial and temporal distribution of galaxies in the original simulation box onto that of the observer light-cone. The parameters of the cone are user-configurable.
• Spectral Energy Distribution Module: 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 then convolved with a set of user-selected filters to compute both apparent and absolute magnitudes.
• Mock Image Module: This module takes the output of both the light-cone and SED modules to construct user-defined mock images. Images can be customised using a range of properties, such as sky area, depth, and observed filter.
• Vis3D Module: Vis3D allows a catalogue to be interactively visualised in 3D within the browser using the mouse and keyboard. The data can be filtered by property and colour-coded by various templates. Views into the catalogue can be saved for later access.