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

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

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

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) http://www.euro-vo.org/pub/fc/cases/srm.pdf

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

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.”

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

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

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

Science Demos and early VO Science

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 http://www.euro-vo.org/astrovirtel/index.html 20+ publications listed on AstroVirtel pages

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

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

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

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

More published results

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...

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

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

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 -20 1123 (Gill & Kapteyn 1896) (and in VizieR catalogs...)

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

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

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

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

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

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

Steps Elliptical Galaxy Selection luminous red galaxies r<19 – 112510 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

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

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

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)

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

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!

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