miguel cerviñoiau symp. 241 dec. 2006 what can be done to make the virtual observatory useful for...

Miguel Cerviño IAU Symp. 241 Dec. 2006 QuickTime™ and aTIFF (Uncompressed) decompressor

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What can be done to make the Virtual Observatory useful for stellar

population analysis?

Miguel Cerviño (SVO)1,2 Santi Cassisi (Vosb.It)1,2

Herve Wozniak (VO-France)1,2

1Theory Expert Group (EuroVO-DCA)2Theory Interest Group (IVOA)






What is VO?The Virtual Observatory will be a system that allows astronomers to interrogate multiple

data centers in a seamless and transparent way, which provides new powerful analysis and visualization tools within that system, and which gives data centers a standard framework for publishing and delivering services using their data. This is made possible by standardization of data and metadata, by standardization of data exchange methods, and by the use of a registry, which lists available services and what can be done with them.

International Virtual Observatory Alliance Guidelines for Participation http://ivoa.net/Documents/latest/IVOAParticipation.html

The long term vision is not one of a fixed specific software package, but rather one of a framework which enables data centers to provide competing and co-operating data services, and which enables software providers to offer a variety of compatible analysis and visualization tools and user interfaces. The first priority for the VO projects worldwide is to develop the standardized framework, which will allow such creative diversity.

Where is the “system”? Does it mean operative system? NO, it means a working environment, just like KDE, Gnome or WindowsUhmm, does it mean something

like IRAF? But there is a lot of software already….

… but it says “their data”…Does it mean using “analysis tools” with data from different machines and formats whatever the operating system?

YES!!

Ok, so it is needed a standard way to DESCRIBE data (besides the “data format” that does not need to change) so the MAIN POINT is HOW TO DESCRIBE the data themselves (metadata)…… and to establish the communication between machines…… and “yellow-pages” for search resources…






What can VO do for stellar population analysis?

For model developers: Common way to describe/tranfer/use the data

VOtable: Data description + data (any format)

It is not needed different “drivers” for different inputs and/or different groups (atmosphere libraries, tracks, isochrones, SSPs...)

For model users: Democracy in model use (democracy = to make a choice and to be able to justify this choice in a physical bases)

Common way to use data

All model with similar visibility

You can chose the best model (or model subset)

It will need that model developers explain differences among models (but it is also needed otuside VO world ;)

Remember SSP challenge results: use different models (including different algorimths: Fuel Consumption vs. Isochrone synthesis) to test your result






No-VO Inside VO

You can choose! And you can justifyYour choice based in physical reason!






What can be done to make the VO useful for stellar population analysis?

1. VO can is yet useful for stellar populations!!

1. It can retrieves observational data

2. It can retrieves theoretical data (SSPs etc...)

2. But it can be much more useful:

1. If model developers are able to describe explicitly the assumptions that are done implicitly (and sometimes not described in papers): e.g. Are atmospheres interpolated? How are isochrones obtained? Which and how interpolations are used? Which method is use to integrate the isochrone? How deals with isochorne points outside the parameter space covered by the atmosphere library?

Any case, it is not a VO requisite, but a science requisite






- A probabilistic result? - Generally provides a mean value of a distribution

- But also provide (sometimes) the variance of such distribution, parameterized as Surface Brightness Fluctuations

- And why do not use skweenes and kurtosis also? - And why not all the distribution? (e.g. Monte Carlo simulations)

2.- If we establish what a model result is:

- A deterministic result? (given age/ metalicity/ SFH/ IMF/ extinction...) a unique value of the integrated luminosity?

Again, it is not a VO requisite, but a science requisite, since it affects its use andinterpretation

Note: It also affects to tracks/isochrones (e.g. rotation, TP-AGB...), results of SSP challenger results (best 2 vs. 2 distribution) etc...






Conclusions

1. VO idea is to help to produce science more efficiently

2. VO its in a no-return point (models are there and will be there; either provide by developers or provide by third-parties)

3. VO is now useful for stellar population analysis, but it can be much more useful

4. At this moment, VO requirements are also science requirements

5. If you are interesting, we will create a mailing list to define what and how describe atmosphere/ tracks/ isochrones/ synthesis models/ analysis tools etc.. (contanct Herve, Santi, or Miguel)

miguel cerviñoiau symp. 241 dec. 2006 what can be done to make the virtual observatory useful for...

Documents

data description data

data votable

data format

multiple data centers

cooperating data services

theoretical data ssps

model developers

vo useful