1 / 39

VLBI/e-VLBI

VLBI/e-VLBI. An Introduction for Networkers Tasso Tzioumis, ATNF, CSIRO. Outline. Caveat: A Basic introduction Not a review of the latest techniques and results Radio Interferometry & VLBI Why: Science with VLBI How: Technology e-VLBI: Impact. Radio Interferometry.

eaton-benton
Download Presentation

VLBI/e-VLBI

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. VLBI/e-VLBI An Introduction for Networkers Tasso Tzioumis, ATNF, CSIRO

  2. Outline • Caveat: A Basic introduction • Not a review of the latest techniques and results • Radio Interferometry & VLBI • Why: Science with VLBI • How: Technology • e-VLBI: Impact

  3. Radio Interferometry Simple Interferometer • Baseline B: Distance between antennas • “Virtual” telescope of diameter B.cos  (projected baseline) • Fringe pattern provides information on structure and position of the radio source Fringe Pattern

  4. Earth Rotation Aperture Synthesis uv- diagram • Baseline length and orientation (as viewed from the source) changes as the Earth rotates  new information on source structure. • uv-diagram - an indicator of imaging “quality” of an array of antennas • more antennas  filled uv  better image fidelity

  5. Connected Element Arrays VLA • Baselines up to 10s of kms • “Real-time” detections • Full-time operation ATCA

  6. MERLIN • Baselines 5-200 kms • Radio-linked  “real-time” Operation • e-MERLIN - fibre links under construction

  7. VLBI Arrays

  8. LBA x NTD x New Norcia

  9. VSOP

  10. Resolution Atmosphere gives 1" limit without corrections which are easiest in radio Jupiter and Io as seen from Earth 1 arcmin 1 arcsec 0.05 arcsec 0.001 arcsec Simulated with Galileo photo

  11. Why? Unique VLBI Science Zooming in!

  12. Cen A

  13. Active Galactic Nucleus Model Hercules A

  14. 3C236

  15. Superluminal motion

  16. Wide-field Imaging - surveying

  17. Gravitational lensing Double-quasar 0957+561 - VLBA+EVN, 18cm PKS1830-211 Einstein Ring MERLIN, 5cm

  18. NGC 4258 • Galaxy with disk • Radio continuum jet • Jet on one side obscured • H2O masers • Continuum amplifies maser emission (in green) • Tangential to disk maser emission – faint red & blue spots at Keplerian(point mass) rotation • First real measurement of nuclear Black Hole mass • Add time dimension (4D): geometric distance! • Image courtesy: Lincoln Greenhill

  19. M82 Starburst

  20. SN1993J Bartel et al

  21. Mira Variable TX Cam • 43 GHz SiO maser emission around a star • No continuum emission at all • Actually many frequencies with masers; composite • movie! • Image courtesy: Phil Diamond & Athol Kembal

  22. SS433 • X-ray binary • Precessing jets • 0.26c jet speed • Baryonic jets Model Movie of VLBI Observations

  23. 10 cm Baseline Length 1984-1999 Baseline transverse 10 cm Astrometry & Geodesy • Fundamental reference frames • International Celestial Reference Frame (ICRF) • International Terrestrial Reference Frame (ITRF) • Earth rotation and orientation relative to inertial reference frame of distant quasars • Tectonic plate motions measured directly • Earth orientation data used in studies of Earth’s core and Earth/atmosphere interaction • General relativity tests • Solar bending significant over whole sky

  24. SGR A* - The Galactic Centre Measures rotation of the Milky Way Galaxy

  25. Spacecraft Navigation • Astrometry relative to background radio sources • Can measure micro-arcsecond position differences • Huygens spacecraft at Titan: • January 2005, VLBI tracking • Determine probe position during descent • Accuracy ~1 km • Fringes detected but data still being reduced

  26. How? - current systems • Data recorded on tape or disk systems at < 1 Gbps • Transported (slow!) to correlator facilities • Data processing by correlator

  27. VLBI Recorders - Mkx

  28. LBA Disk system S2 VLBI Recorder

  29. The Future e-VLBI

  30. e-VLBI global data transport

  31. e-VLBI Science Impact • Real-time operation (cf ATCA, VLA,…) • Fast response to “targets of opportunity” like flaring or exploding stars • Monitoring of evolving events • Immediate assessment of results • Higher sensitivity from high data rates • imaging sources at the edge of the universe • Very high quality imaging • (very efficient way to increase sensitivity cf building larger antennas) • Support high data rates of processed data • Facilitate “wide-field” imaging • Utilise GRID computing? • Database “mining”

  32. SKA - an e-VLBI array? SKA 1Tbit/s data transport requirement in inner array 100 Gbit/s data transport requirement in outer array

  33. Operational Impact • Flexible scheduling • Fast response to astronomical events • Robust operation • Real-time performance monitoring • Immensely easier data transport • Remote antenna operation • Remote data analysis • Distribution of processed data to users  Lower operating costs?

  34. Summary • VLBI offers a unique look at the universe - a “zoom” camera • e-VLBI will revolutionise VLBI operations • e-VLBI will enhance VLBI sensitivity, response time and flexibility • SKA will be an e-VLBI array • Networking is the future for VLBI

  35. VLBA

  36. The VLBA

  37. EVN

  38. Kx recorders

More Related