Theory in the VO
There are many fields in Astrophysics with a strong need of direct and rigorous comparisons between theoretical models or simulations and real data. However, the different architectures, programming codes, formats, etc, make it, most of the times, extremely difficult and inefficient.
In order to define the requirements needed for a full interoperability between observations and models, an IVOA Theory Group was created in January 2004. Dr. Miguel Cerviño (IAA-CSIC) will be the contact point for the SVO.
Access protocols to theoretical data
- One of the first issues undertaken by the IVOA Theory Group was the definition of query protocols adequate for theoretical data: the VO protocols already defined for observational data (Conesearch, SSAP, SIAP,...) are based on absolute positions on the sky and, in most cases, cannot be applied to theoretical models. Moreover, for theoretical models, there is not a common set of input parameters that could play the role of the coordinates for observational data as each model has its own collection of input parameters that normally differ from one model to another.
- To handle this problem, SVO-LAEFF and ESA-VO have defined TSAP (Theoretical Spectra Access Protocol) as an attempt to incorporate theoretical models to the VO. With TSAP, a ``format=metadata'' dialog is used in such a way that the client can ask the server for the collection of the allowed input parameters as well as the valid values for each one of them. In this way, the client can build an adequate form for a given model and shows it to the user, who will select the preferred parameter values or ranges. Afterwards, the client will build a valid query and will send it to the data server which will give back the results in VOTable format.
- TSAP has been presented in the Theory Group sessions of the IVOA Interoperability meetings held in Kyoto (May05) and Madrid (Oct05).
- A more detailed description of TSAP can be found here.
- TSAP is considered part of the Simple Spectra Access Protocol (SSAP)
SVO-LAEFF Theoretical Data Server
- SVO-LAEFF has implemented TSAP services for a number of datasets
- The task of implementing a TSAP and/or a web page for theoretical models can be a laborious work in many cases. To simplify it, SVO-LAEFF has developed DB2VO, a php application that, taking a collection of ASCII files (the grid of models) and a table with the associated description as input parameters, is able to build both the TSAP service and the web interface in an automated way.
Development of analysis services
- SVO collaborates in the development of PGos3, a federative project led by INAOE whose goal is to study the star formation history in galaxies. A use case based on the comparison using TSAP between different grids of evolutionary synthesis codes with observational data was presented in the IVOA interoperability meeting held in Madrid in October 2005.