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EVLA

EVLA. Bryan Butler. What is the EVLA?. keep VLA antennas, pads, rail system, buildings, etc…, i.e., all the infrastructure upgrade: Front Ends (feeds + Rx) LO Data transmission Correlator software add antennas & pads (Phase II). What is the EVLA?. Results:

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EVLA

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  1. EVLA Bryan Butler

  2. What is the EVLA? • keep VLA antennas, pads, rail system, buildings, etc…, i.e., all the infrastructure • upgrade: • Front Ends (feeds + Rx) • LO • Data transmission • Correlator • software • add antennas & pads (Phase II)

  3. What is the EVLA? • Results: • continuous frequency coverage from 1 - 50 GHz • improved sensitivity: 1 Jy in 12 hours • higher resolution: 10 masec @ 20 GHz (Phase II) • better brightness sensitivity: 0.1 mK @ 10 GHz @ 10" • more flexible correlator (WIDAR): 16384 channels available at full bandwidth, 4.2 million channels at highest spectral resolution; independently tunable subchannels • dynamic scheduling • much easier for the astronomer to use

  4. EVLA Sensitivity

  5. Phased Deployment Split into two “phases” - Phase I and Phase II, for strategic reasons. Phase I - hardware, electronics, correlator, software currently funded (details on next slide) Phase II - 8 new antennas, 20 new close-packed pads proposal just went in to NSF

  6. Phase I Science Themes • Four science themes chosen to underscore the capabilities of the EVLA, and radio astronomy: • The Magnetic Universe • The Obscured Universe • The Transient Universe • The Evolving Universe

  7. Phase I Specific Science Goals The Phase I proposal identified the following key science goals: • Measuring the 3-dimensional motions of ionized gas and stars in the center of the Galaxy. • Conducting unbiased searches for redshifted atomic and molecular absorption lines. • Measuring the 3-dimensional structure of magnetic fields on the sun. • Mapping the changing structure of the dynamic heliosphere. • Accurate positions, sizes, and expansion estimates of ~100 GRBs every year. • Mapping the magnetic fields in individual galaxy clusters. • Observing ambipolar diffusion and thermal jet motions in young stellar objects. • Measuring the rotation speeds of asteroids.

  8. Phase I Status • A proposal for $50M (2000 dollars) was submitted to the NSF in May 2000. • After approval by the NSB, funding from the NSF began in 2001, at a rate of $5M/year, with completion anticipated by 2012. • Canadian government approval for full correlator funding (US$14.4M) came in 2003. • Mexican funds $2M are also available. • Prototyping is now well advanced. First light was achieved in October 2003; first fringes in April 2004. • Outfitting with full production electronics will begin later this year. • Fully operational by 2012.

  9. Phase I Status

  10. Phase I Status

  11. First Light • EVLA achieved first light in October, 2003. • X-Band (8 – 12 GHz) • Bandwidth of 1 GHz. • Utilized all new EVLA electronics • Drift scan of the moon: expected antenna temperature of about 200 K.

  12. Phase II Status • The Phase II (completion) proposal was submitted to the NSF in April 2004. • Lengthy approval process expected. • Competition for MRE funding very stiff. • If approved, a 7-yr timescale will be needed: if we start in 2005, can complete by 2012.

  13. The Frequency-Resolution Plane

  14. Why both EVLA and ALMA? • Non-thermal processes emit at cm-wavelengths • Lower dust opacity at long  • Cosmic expansion shifts spectrum to longer 

  15. Why both EVLA and ALMA? • At z > 5 or so, only the high energy transitions of CO will be available to ALMA

  16. Why both EVLA and ALMA? • The inner portions of dense star-formation regions are optically thick at mm 

  17. EVLA - WVR The EVLA, like ALMA, will need phase correction. Current efforts are very encouraging see Claire’s poster…

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