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ESA Mission Gaia Unraveling the chemical and dynamical history of our Galaxy

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ESA Mission Gaia Unraveling the chemical and dynamical history of our Galaxy

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  1. ESA Gaia: Expectation for Astroparticle PhysicsRené Hudec, Vojtěch Šimon, Lukáš Hudec& Collaborators & Gaia CU7 consortiumGroup of High Energy AstrophysicsAstronomical Institute of Academy of Sciences of the Czech Republic, Ondřejov, Czech RepublicISDC Versoix, SwitzerlandSanta Fe GRB Workshop 2007Reference: http://sci.esa.int/gaia/

  2. ESA Mission Gaia Unraveling the chemical and dynamical history of our Galaxy Albeit focusing on astrometry, Gaia will also provide spectrophotometry for all objects down to mag 20 over 5 years operation period. Typically 50 to 200 measurements per object including optical counterparts of HE sources.

  3. Gaia: Design Considerations • Astrometry (V < 20): • completeness to 20 mag (on-board detection)  109 stars • accuracy: 10–25 μarcsec at 15 mag (Hipparcos: 1 milliarcsec at 9 mag) • scanning satellite, two viewing directions  global accuracy, with optimal use of observing time • principles: global astrometric reduction (as for Hipparcos) • non-negligible fraction TeV/VHE sources including OTs and OAs of GRBs will be within the detection limit • dark matter in the Galactic disk study measuring the distances and motions of K giants • Photometry (V < 20): • astrophysical diagnostics (low-dispersion photometry) + chromaticity • Teff ~ 200 K, log g, [Fe/H] to 0.2 dex, extinction • Radial velocity (V < 16–17): • application: • third component of space motion, perspective acceleration • dynamics, population studies, binaries • spectra: chemistry, rotation • principles: slitless spectroscopy using Ca triplet (847–874 nm)

  4. Gaia: Complete, Faint, Accurate

  5. GAIA capabilities • Distances: • <0.1% for 700 000 stars <1% for 21 million <10% for 220 million • Transverse motions: • <0.5% km/s for 44 million <3 km/s for 210 million <10 km/s for 440 million • Radial velocities to a few km/s complete to V=17-18 • 15-band photometry (250-950nm) at ~100 epochs over 4 years • Complete survey of the sky to V=20, observing 109 objects: • 108 binary star systems (detected astrometrically; 105 orbits) • 200 000 disk white dwarfs • 50 000 brown dwarfs • 50 000 planetary systems • 106-107 resolved galaxies • 105 quasars • 105 extragalactic supernovae • 105-106 Solar System objects (65 000 presently known)

  6. Satellite and System • ESA-only mission • Launch date: 2011 • Lifetime: 5 years • Launcher: Soyuz–Fregat from CSG • Orbit: L2 • Ground station: New Norcia and/or Cebreros • Downlink rate: 4–8 Mbps • Mass: 2030 kg (payload 690 kg) • Power: 1720 W (payload 830 W) Figures courtesy EADS-Astrium

  7. Schedule 2020 2004 2008 2016 2000 2012 Concept & Technology Study (ESA) ESA acceptance Re-assessment: Ariane-5 Soyuz Technology Development Design, Build, Test Launch Cruise to L2 Observations Data Analysis Catalogue Early Data

  8. Payload and Telescope Basic angle monitoring system Rotation axis (6 h) Two SiC primary mirrors 1.45  0.50 m2 at 106.5° SiC toroidal structure (optical bench) Combined focal plane (CCDs) Superposition of two Fields of View (FoV) Figure courtesy EADS-Astrium

  9. Astrometric instrument: Light path 1 2 4 3

  10. Photometry Measurement Concept Blue photometer: 330–680 nm Red photometer: 640–1000 nm Figures courtesy EADS-Astrium

  11. Photometry Measurement Concept (2/2) RP spectrum of M dwarf (V=17.3) Red box: data sent to ground White contour: sky-background level Colour coding: signal intensity Figures courtesy Anthony Brown

  12. Figure courtesy Alex Short Focal Plane 104.26cm Wave Front Sensor Red Photometer CCDs Blue Photometer CCDs 42.35cm Wave Front Sensor Radial-Velocity Spectrometer CCDs Basic Angle Monitor Basic Angle Monitor Star motion in 10 s Sky Mapper CCDs Astrometric Field CCDs Sky mapper: - detects all objects to 20 mag - rejects cosmic-ray events - FoV discrimination Astrometry: - total detection noise: 6e- Total field: - active area: 0.75 deg2 - CCDs: 14 + 62 + 14 + 12 - 4500 x 1966 pixels (TDI) - pixel size = 10 µm x 30 µm = 59 mas x 177 mas Photometry: - two-channel photometer - blue and red CCDs Spectroscopy: - high-resolution spectra - red CCDs

  13. On-Board Object Detection • Requirements: • unbiased sky sampling (mag, color, resolution) • no all-sky catalogue at Gaia resolution (0.1 arcsec) to V~20 • Solution: on-board detection: • no input catalogue or observing programme • good detection efficiency to V~21 mag • low false-detection rate, even at high star densities • Will therefore detect: • variable stars (eclipsing binaries, Cepheids, etc.) • supernovae: 20,000 • microlensing events: ~1000 photometric; ~100 astrometric • Solar System objects, including near-Earth asteroids and KBOs • fraction of OTs and OAs of GRBs

  14. Sky Scanning Principle 45o Spin axis 45o to Sun Scan rate: 60 arcsec/s Spin period: 6 hours Figure courtesy Karen O’Flaherty

  15. Scanning law Observations over 5 months Ecliptic co-ordinates

  16. GAIA and our Galaxy 10 as/yr = 1 km/sec at 20 kpc 10 as = 10% distances at 10 kpc

  17. Data Processing Concept (simplified) From ground station Community access Ingestion, preprocessing, data base + versions, astrometric iterative solution ESAC (+ Barcelona + OATo) Overall system architecture ESAC Data simulations Barcelona Object processing (shell tasks) + Classification CNES, Toulouse Photometry Cambridge (IOC) + Variability Geneva (ISDC) Spectroscopic processing CNES, Toulouse Status and contributions to be confirmed

  18. *DPAC: Data Processing and Analysis Consortium **DPACE: DPAC Executive

  19. Czech Republic expected to join ESA as a full member in Jan 2009

  20. GaiaCU7 Sub-workpackage on Optical Counterparts of High-Energy SourcesRené Hudec& CollaboratorsLeuven, Nov 9-10, 2006

  21. Motivation of the GaiaCU7 Sub-workpackage on Optical Counterparts of High-Energy Sources • Many of HE&VHE sources (including OAs and OTs of GRBs) have also optical emission, mostly variable and accessible by Gaia • Monitoring of this variable optical emission provides important input to understanding the physics of the source • Multispectral analyses

  22. Optical Counterparts of High Energy Sources The objective of the work package: • The investigations and analyses of optical counterparts of high energy astrophysics sources based on Gaia data and complex analyses with additional data. Specifically: • For selected targets, multispectral analyses using Gaia and other databases (such as the satellite X-ray and gamma-ray data, optical ground-based data etc) may be feasible. • Analyses of long-term light changes and their evolution • Analyses of active states and flares • The study and understanding of related physical processes. • Spectrophotometry, relation of brightness and spectrum/colour. • For selected sources, dedicated complex analyses. • Statistics of the whole sample of objects.

  23. Some examples • LMXRB • HMXRB • Optical Afterglows and Optical Transients of GRB Optical LC of OT of GRB060116, Jelinek et al. 2006 Long-term optical changes of Sco X-1/V818 Sco, Hudec 1981 Inactive state optical LC of Her X-1/HZ Her, Hudec and Wenzel 1976

  24. Rapidly evolving light curves of some LMXRB, Muhli et al., 2004 Thermonuclear bursts related to NS? Gaia: Optically faint LMXB often suffer by poor optical coverage/analyses, especially on long-term time scales. Here can Gaia provide important inputs. Ser X-1/MM Ser LMXRB & X-ray burster Wachter 1997 Optical bursts related to X-ray bursts: reprocessing of X-rays in a matter near the NS

  25. Even gamma-ray sources do have optical counterparts accessible by Gaia >90% accessible with Gaia Optical B and V magnitudes of optically identified INTEGRAL gamma-ray sources … most are brighter than mag 20, and more than half are brighter than mag 15

  26. Gaia and GRBs: Photometry • There will be a variety of OTs detected by Gaia • The real OTs and OAs of GRBs can be, among these, recognized according to their characteristic power-law fading profie • However, the sampling provided by Gaia, is not optimal for these goals, hence not always we can expect realiable and confirmed detection of OT of GRB based only on photometry by Gaia

  27. Gaia and GRBs: Spectroscopy • The primary strength of Gaia for GRB study is the fine spectro-photometry • The OAs of GRBs are known to exhibit quite typical colors, distiguishing them from other types of astrophysical objects (Simon et al. 2001, 2004) • Hence a realiable classification of OTs will be possible using this method

  28. Specific colors of OAs of GRBs (Simon et al., 2001, 2004) Notice the prominent clustering of colors and negligible color evolution during decline. V-R vs. R-I diagram of OAs of GRBs (t-T0<10.2 days) in observer frame, corrected for theGalactic reddening. Multiple indices of the same OA are connected by lines for convenience. The mean colors (centroid) of the whole ensemble of OAs (except for GRB000131) are marked by the large cross. The colors of SN1998bw are shown only for comparison. The representative reddening paths for EB-V=0.5 are also shown. Positions of the main-sequence stars are included only for comparison.

  29. GaiaCU7 Sub-workpackage on Cataclysmic VariablesRené Hudec & CollaboratorsLeuven, Nov 9-10, 2006

  30. Cataclysmic Variables and Related Objects The objective of the sub-work package: • The investigations and analyses of Cataclysmic Variables and related objects (including supernovae, novae, recurrent novae, nova-like variables, dwarf novae, polars, intermediate polars, symbiotic stars) based on Gaia data (photometry and spectrophotometry) as well as complex analyses with additional data. • Some of the CVs are candidates for VHE emission (SNe, AE Aqr, AM Her...)

  31. SN 1987A Nova V1500 Cyg RS Oph Recurrent Nova U Gem Dwarf Nova Z Cam Dwarf Nova Z And Symbiotic Variable

  32. GaiaCU7 Sub-workpackage on AGN

  33. Gaia and AGN • Gaia will detect all AGN brighter than mag 20 • Photometry and spectro-photometry • Including TeV AGN/blazars • Providing valuable simultaneous and quasi-simultaneous optical data for TeV blazars • Automated recognition of AGN by their spectra, searches for spectral changes

  34. Variability studies based on low dispersion spectra Simulated low dispersion Gaia spectrum Real low dispersion spectrum from digitized Schmidt spectral plate Application of algorithms developed for digitized astronomical archival plates (Hudec L., 2007) on Gaia

  35. Relation of spectral and photometric variations T. Jarzebowski, 1959 X Cam Mira Variable Spectral Variations M0 to M6.5 Amplitude 1.4 mag in R

  36. Example spectra of cataclysmic variables & blazars (digitised Hamburg Survey) Blazar CV CV CV CV Blazar

  37. Novel algorithms for automated analyses of digitized spectral plates • Developed by informatics students • Automated classification of spectral classes • Searches for spectral variability (both continuum and lines) • Searches for objects with specific spectra • Correlation of spectral and light changes • Searches for transients

  38. The Motivation • The archival spectral plates taken with objective prisma offer the possibility to simulate the Gaia low dispersion spectra and related procedures such as searches for spectral variability and variability analyses based on spectro-photometry • Focus on sets of spectral plates of the same sky region covering long time intervals with good sampling

  39. Automatic classification of stellar objective prism spectra on digitised plates, a simulation and a feasibilty study for low-dispersion Gaia spectra Left: investigated spectrum Right: Calibration spectrum (Hudec L., 2007)

  40. The End

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