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:– 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

EVLA Sensitivity

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

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

Phase I Specific Science Goals

The Phase I proposal identified the following key science goals:

• 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.

• 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.

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.

Phase I Status

Phase I Status

QuickTime™ and aTIFF (LZW) decompressor

are needed to see this picture.

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.

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.

The Frequency-Resolution Plane

Why both EVLA and ALMA?

•Non-thermal processes emit at cm-wavelengths

•Lower dust opacity at long

•Cosmic expansion shifts spectrum to longer

• At z > 5 or so, only the high energy transitions of CO will be available to ALMA

Why both EVLA and ALMA?

• The inner portions of dense star-formation regions are optically thick at mm

Why both EVLA and ALMA?

EVLA - WVR

The EVLA, like ALMA,

will need phase correction.

Current efforts are very

encouraging

see Claire’s poster…