1. Mark Allen (CDS, Observatoire de Strasbourg)
Science with the VO
Mark Allen
(CDS, Observatoire de Strasbourg)

2. Outline Example Science Drivers Science 'Reference Mission'
The 'VO approach' & Common Aspects
Demonstrations and Early VO Science
Published examples
Challenges and Opportunities

3. Example science drivers
Find all info on a given set of objects
Defined by positions, colours, morphology,...
Build SEDs from multi-archive data
Accounting for instrumental, sensitivity, aperture effects
“Outlier Science” Multi-d parameter searches
Compare LSS with 'virtually observed' N-body simulations
Re-analyse the SLOAN, MACHO
Multi- census of AGN
Build a survey to search for Cosmic Shear

4. AVO Science Reference Mission
Key scientific results that a European VO should be able to achieve when fully implemented
Consists of science cases over broad range of astronomy and the related requirements
AVO Science Advisory committee (2005)

5. Science Cases Galactic Extragalactic Cosmological
Circumstellar disks: from pre-Main Sequence stars to stars harbouring planets
Intermediate Velocity Clouds
Which Star will go Supernova next?
Initial Mass Function within 1kpc: Planetary to Stellar Masses
Initial Mass Function for Massive Stars
Contributions of Low and Intermediate Mass Stars to the ISM
Galaxy Formation and Evolution from z=10 to 0.1
Build-up of Supermassive Black Holes
Formation and Evolution of Galaxy Clusters
Correlation of CMB, radio/mm and optical/NIR Galaxy Surveys
Extragalactic
Cosmological

6. Galaxy Formation and Evolution from z=10 to 0.1
When did the 1st objects form?
What are the progenitors of present day massive ellipticals?
How many massive galaxies at z>1,2,4?
How do SF and galaxy stellar mass densities evolve?
Required data
Deep Multi-wave surveys (GOODS, COSMOS)
HST+ACS bviz imaging
SLOAN
Optical spectroscopy
MERLIN, GMRT, VLA, ATCA radio
Chandra and XMM-Newton X-ray
Spitzer mid-IR
Future sub-mm
GALEX UV imaging
“Only now, and only with through the VO, are the datasets large enough, and the tools mature enough that Galaxy Formation and Evolution can be examined in a meaningful way.”

7. VO approach to the problem
Extract sample from data
Perform Sextractor type photometry
Cross correlate with images, catalogues, spectra Crucial that output results are scientifically useable and reliable Matching of PSF, consisitent photometric apertures, treatment of noise, and upper limits
Sanity checks like stellar colours
Output multi-band catalogue, and colour-colour diagrams
Visualize output colour-colour space
Photometric z from SEDs (Template SED libraries, extinction curves etc.)
Physical Parameters – L, E(B-V), SFR, M/L  stellar mass
Comparison with star formation scenarios and synthetic spectra
Morphological analysis
Stack images at same wavelength, or spectra at different redshifts
Build average spectra for specific object classes
Angular clustering analysis
Comparison with mock catalogues from theoretical simulations

8. Common aspects Browsing/searching of data and distributed information
Manage large amounts of distributed heterogeneous data
Combining Multi-wavelength data taking into account different:
Units, photometric systems
spatial, wavelength and time coverage
resoultions/PSF, observing technique

9. Catalogues: Large-Small, Sparse-Dense Taking into account:
Cross-Matching
Catalogues: Large-Small, Sparse-Dense
Taking into account:
positional uncertainties, resolution, completeness
extra constraints: e.g. colour, object type, environment
Compare observations with models
Virtual observations of models
Projection of models to observed parameter space
Spectral fitting/classification

10. Science Demos and early VO Science

11. Exploit archives as virtual telescopes (3 proposal cycles 2000-2003)
VO science on HST, ESO: VLT, NTT, WFI, ISO archives
advanced searching of achive
exposure/seeing/field density
location e.g. for pre-discovery images for asteroids
20+ publications listed on AstroVirtel pages

12. Early demonstration project identifies new L-type Brown Dwarf
Found in SDSS/2MASS correlation designed to reproduce known (~200) Brown Dwarfs
SDSS 15M sources, 2MASS 160M
Was done as protoype, now used as NVO OpenSkyQuery training example

13. VO Visualisation and Data Discovery
Demo 2003: First Light
VO Visualisation and Data Discovery
Demo 2004: First Science
Searching for type 2 Quasars using Virtual Observatory tools
Demo 2005
AGB to Plantary Nebulae transition
Workflow: SEDs to Models

14. Discovery of QSO 2s with VO tools
- GOODS Optical ACS data & catalogues
- Chandra X-ray catalogues
- Select absorbed X-ray sources
- Cross-match X-ray and optical
- Apply empirical estimator for Lx
- Check against spectroscopy
Lx>1044 : QSO 2

15. Science Conclusions Using the deepest Chandra X-ray, and HST imaging
& Empirical estimator for Lx we find
68 New type 2 AGN
31 Qualify as QSO 2, z~4
Many more QSOs than predicted
Published: Padovani, Allen, Rosati, Walton A&A 2004

16. More published results

17. Using VO tools to investigate distant radio starburst hosting obscured AGN in the HDF(N) region, Richards et al., A&A, 472, 805 (2007)
Albus 1: a very bright White Dwarf candidate, Caballero & Solano, ApJ, 665, L151 (2007)
Flare productivity of newly-emerged paired and isolated solar active regions, Dalla, Fletcher, & Walton A&A, 468, 1103 (2007)
Radio-loud Narrow-Line Type 1 Quasars, Komossa et al., AJ, 132, 531 (2006)
Luminous AGB stars in nearby galaxies. A study using VO tools, Tsalmantza et al., A&A, 447, 89 (2006)
+ more...

18. Example: Serendipitous Outlier
Caballero & Solano 2007, ApJ, 665, L151 'ALBUS 1: A very bright white dwarf candidate'
found a bright source with
very blue VT-Ks colour
appreciable proper motion
mag. and colours --> White Dwarf Candidate

19. Found in optical-NIR study to characterize young stars and brown dwarfs surrounding εOri and δOri
VO aspects:
Correlate Tycho-2 and 2MASS catalogs [in 10 45' radius fields at same Gal. lat.]
also: SuperCOSMOS, USNO-B1, NOMAD and DENIS
excluded radio(VLA), mid-IR(IRAS), UV (EUVE), X-ray(ROSAT)... or object in literature (SIMBAD)
Aladin & VO catalog interoperability

20. ALBUS 1 is a Helium-rich subdwarf
published Aug 2007, and then ...
spectrum obtained:
ALBUS 1 is a Helium-rich subdwarf
Also known as CPD (Gill & Kapteyn 1896) (and in VizieR catalogs...)

21. Example: Solar Physics
2 papers utilizing AstroGrid workflow system
1. 'Flare productivity of newly-emerged paired and isolated solar active regions' Dalla et al., 2007, A&A, 468, 1103
2. 'Invisible subspots and rate of magnetic flux emergence' Dalla et al. 2008, A&A, 479, L1

22. Analysed 7000+ sunspots from over 25 year period
Some areas of the disk are missing new sunspots compared to others
because when they are gowing rotation caries them away from centre of disk

23. AstroGrid workflows Slide courtesy of S. Dalla
We used AstroGrid workflows to:
(1) retrieve region catalogues and identify ‘new’ regions;
(2) study the location of emergence with respect to pre-existing regions; and
(3) querying catalogues of flares to establish flare productivity.
Visualisation of results using Topcat.
Slide courtesy of S. Dalla

24. Fossil Groups in the SDSS
US NVO Summer School
The National Virtual Observatory: Tools and Techniques for Astronomical Research. ASP vol. 382
2007 AJ, 134, 1551 Santos, Mendes de Oliveira & Laerte Sodre

25. Fossil Groups – systems with M and LX comparable to clusters of galaxies, but dominated by single isolated large elliptical galaxy
'Fossil' – comes from formation scenario:
collapsed early -> oldest, undisturbed systems
only 15 fossil groups known in literature

26. VO methods to identify new fossil groups in SDSS DR5 – increasing known by x3
Use of
SQL - Structured Query Language
ADQL – Anstronomical Data Query Lang.
OpenSkyQuery VO service

27. Steps Elliptical Galaxy Selection
luminous red galaxies r<19 – sources
Cross-Match with X-ray data
OpenSkyQuery xmatch of SDSS with RASS
constrained by positional uncertainties
Selection of Companions
spectro. and photom. redshifts
Photometric Condition for Fossil Groups
mi > m1 + 2
Analysis of dominant galaxy
Cross-check against known systems

28. Simple expressions applied to large data set in powerful way
-> New Fossil Groups
Query Language expressions published in the paper

29. My observations of current VO science
largely about getting and combining data
once data obtained/selected analysis is mostly by traditional methods
Workflow systems ramping up (esp. AstroGrid)
Scripting with familiar lang. (Python) very promising
End-to-End with VO ?
in practice VO is being used where it is needed
more and more papers acknowledging VO

30. Where's the detailed scientific interoperability?
as required for SRM like problems
first IVOA standards -> good data connectivity
in progress:
characterisation of data – data models
units, PSFs, time/spatial/energy coverage
theory and modeling...
(not to mention Grid, VOSpace, Curation, Access Layers)

31. Comparing with Theory Simplistic demos show interoperability
but immaturity
Need for meetings like this!

32. Opportunities Euro-VO AIDA Calls for Proposals
to carry out Astronomy projects that would benefit from VO.
Support from Euro-VO scientists
Watch for announcements!

34. Field of Streams

35. Your own Field of Streams ...

36. Your own Field of Streams ...