Theory in the Virtual Observatory Gerard Lemson, GAVO

Ringberg, Gerard Lemson The VO  Broad goal  Make results of astronomical research, data and applications, more readily available to larger community, and create value-adding services.  Facilitate:  communication of results  checking of results  use of results  comparison of different results  combination of different results to create new ones  Through  online availability of datasets and applications  standardized publication and discovery mechanisms  standardized description (meta-data, FITS++)  standardized selection mechanisms  standardized form(at)s of transmitted data  value added services  Why ?

Ringberg, Gerard Lemson SDSS ROSAT 2MASS FIRST GAIA

Ringberg, Gerard Lemson ROSAT FIRST GAIA SDSS2MASS

Ringberg, Gerard Lemson  Registry  publication  discovery  Data models  description (UCD)  Query protocols  selection (cone search, ADQL) cone searchcone search  combination (XMatch)  Data access protocols  retrieval (VOTable)  Applications  user interfaces (Aladin)  visualisation (VOPlot)  analysis (…)

Ringberg, Gerard Lemson Theory  Existing protocols not applicable  Position based queries  Combination of different archives less obvious  Data models insufficient  New “observables”  Different “provenance”  Different characterization  More complex data structures  Less well developed history of archiving  No FITS for simulations  New use cases  Theorists : data mining simulation results  Observers : virtual telescope

Ringberg, Gerard Lemson Archiving of simulations  Use relational database  GalICS  SDSS  Halo merger trees from milli-Millennium  data model for trees  SAM galaxy catalogues  links to halos  add merger trees  SQL query interface SQL query interface SQL query interface  (Springel, Croton, Blaizot)  Soon: add dynamic SAM to interface

Ringberg, Gerard Lemson Observed Simulated Thanks to Alexis Finoguenov, Ulrich Briel, Peter Schuecker, MPE) Thanks to Volker Springel Virtual Telescope

Ringberg, Gerard Lemson Virtual Telescope  Use simulations for help in interpreting observations (e.g. Peter Schneider for this morning)  Bring simulations into “observational plane”  Create results similar to observations  Can be analysed with same techniques as observations  Can be compared “directly” to obs-s\  Use cases:  Check observational biases using realistic models  Survey/observation planning  Check models to observations

Ringberg, Gerard Lemson Prototypes  Visualisation  Smac (Dolag) Smac  MoMaF (Blaizot) MoMaF  Virtual telescope 

Ringberg, Gerard Lemson Interoperability: Virtual telescope configuration  Components  simulations  telescope models  foregrounds (incl. lensing)  Specification  “pre-observation image”  interfaces  workflow  Implementations …

Virtual telescope data flow

Ringberg, Gerard Lemson Quotes:  "I think the global virtual observatory is a fantastic idea" - Martin Rees, Physics Today, Feb 2002 ... too much money will be sunk into software;... archives at ground-based observatories should be brought up to snuff before thinking about linking them; and... users won't be able to trust the processed data they call up.“ - Physics Today, Feb 2002  “… that VO nonsense …” - anon, Ringberg 2005

Ringberg, Gerard Lemson Discussion  What do you want from the VO ?  What should VO projects focus on ?  What could/do you contribute to the VO ?  Why is the VO a waste of resources ?  Should spend money on more postdocs.  What are the dangers of the VO?  Too easy to do to bad science.  What are the possible advantages of the VO?  Easier to do good, new science.  Easy to check bad science.