Early Science Specification and Expected Array Evolution

Masao Saito

EA ALMA Project Scientist

EA PS Report 12nd ALMA Users Meeting 2011/1/13

Contents

• Early Science Specification– Minimum Requirement– Stretch

• Galleries

• Summary

EA PS Report 2nd ALMA Users Meeting 2011/1/13 2

EA PS Report 3

ALMA 5 antennas at AOS (2010.6)

2nd ALMA Users Meeting 2011/1/13

9 operational antennas at AOS as of 2011.1

Early Science Concept

• ALMA Early Science Cycle 0 – is expected to span 9 months. – is anticipated that 500-700 hours of array time will

be available for Early Science projects.– Any astronomer may submit a proposal in

response to the ALMA Early Science Cycle 0 Call for Proposals.

– Proposals that best demonstrate and exploit the advertised ALMA Early Science Cycle 0 capabilities, producing scientifically worthwhile results from relatively short observations (averaging a few hours), will be given preference.

EA PS Report 2nd ALMA Users Meeting 2011/1/13 4

Important to understand capability in writing a proposal

Cycle 0 Minimum Spec

• 16 x 12m antenna array • 18 - 250m baselines, 2 configurations• Single field imaging• Frontend

– Band 3 (2SB: 84GHz - 116GHz)– Band 6 (2SB: 211GHz - 275GHz)– Band 7 (2SB: 275GHz - 373GHz)– Band 9 (DSB: 602GHz – 720GHz)

• Set of ~21 spectral modes (see later)• No subarrays, no special modes• Amp Calibration good to 5% (band 3) and less

accurate at high frequencies – 15% at band 9?

EA PS Report 52nd ALMA Users Meeting 2011/1/13

Cycle 0 Capabilities - Stretch

To be decided by ~ mid-March 2011• Polarization: Full Stokes parameters on compact

sources: Q, U and V accurate to 1% of I. • Pointed Mosaics – up to 25 points

• Zero-spacing (single-dish rasters maps) – to cover same area as mosaics – Spectral Line only.

• Baselines up to 500m, 3 configurations (or perhaps some other scheme to give us longer baselines late in the first cycle).

EA PS Report 62nd ALMA Users Meeting 2011/1/13

Spectral modes for Cycle 0

TDM modes Point Spacing1 (MHz) →

Band- MHz 7.8 15.6 31.3

width2 1800 13 23 43

“ASAC” modes in red

FDM modes Spacing of spectral points1 (kHz)→

Band- MHz 7.6 15.3 30.5 61 122 244 488 977

width2 1800           13 23 43

↓ 938         1 2 4  

  469       1 2 4    

  234     1 2 4      

  117 1 2 4        

  58.6 1 2 4          

FDM: Digitization efficiency is ~85% TDM: Digitization efficiency is ~88%.Same mode for 4 basebands

with 122 kHz 1.77 times worse ~ 0.3 mJy /hr at 345 GHz

EA PS Report 72nd ALMA Users Meeting 2011/1/13

EA PS Report 2nd ALMA Users Meeting 2011/1/13 8

1) Spatial Resolution and Field of View

　 Resolution

Field of View　2) Sensitivity　

　

ES cycle0 Resolution

Early Science

)GH(

GH345

)(

250"72.0

z

z

L 　 　ｍ　 　ｍ

　 　　

)GH(

GH345"15

z

z

　 　　 　　

)(345@2sec3600

sec23.01

2

1

2

1

polaridualGHzGHz

GHztmJy

　　

• Spatial Resolution Max baseline of SMA ～ 600m ALMA ES (cycle0) ～ 250m

• 感度 （ 2GHz Bandwidth 1 3.2mJy @ 345GHz) 　 SMA integ time(WV 2.50mm) τ=4.0hr ALMA integ time(WV 1.26mm) τ=18.4sec　

※ (SMA http://sma1.sma.hawaii.edu/beamcalc.html , ALMA OT IT3) 　　　　　　　　　　　　　　　　　　　　　　

ALMA needs1/780 integtimeof SMA

Similar to SMA extended Configuration

Cycle0 Sensitivity (Comparison with SMA)

SMA

EA PS Report 92nd ALMA Users Meeting 2011/1/13

SMA 6hr(on source 4hr)Extended configuration 　

ALMA 5min integ time250m configuration 　

Contour every 5 %

20% level

SMA サイト http://sma1.sma.hawaii.edu/beamcalc.html で計算

Contour every 10 %

Similar beam sizewith similar sidelobe level

Cycle0 PSF(Comparison with SMA)

EA PS Report 102nd ALMA Users Meeting 2011/1/13

Example

EA PS Report 2nd ALMA Users Meeting 2011/1/13 11

Early Science 1hr integ 5sigma detection limit

JCMT Disk Survey in Taurus by Andrews+05

Cycle 0: UV coverage and PSF

https://safe.nrao.edu/wiki/bin/view/ALMA/EarlyScienceSims

UV coverage and PSF by CASA image simulator with 5 min and 8 hr integrationALMA site: latitude = -23 degrees16 12m antennasMax Baseline 250mTentative Array Configuration

Antennas (Blue dots) and Pads (pink dots) 120 baseline UV Plane

FOV ~14.9 arcsec ＠ 345GHz

EA PS Report 122nd ALMA Users Meeting 2011/1/13

Taurus(04h30m,25d00m) の PSF@345GHz

コントアは 0.05(5%) 刻み

5 minutes integration 8 　 hours integration

• beamFWHM(0.62”,0.92”)PA ～ -20deg

• side-lobe-2% ～ 20%

• 1σ sensitivity (2GHz BW)0.86mJy (17.2mK)

• beamFWHM(0.69”,0.85”)PA ～ 40deg

• side-lobe-4% ～ 6%

• 1σ sensitivity (2GHz BW)0.088mJy (1.71mK)

EA PS Report 132nd ALMA Users Meeting 2011/1/13

Orion(05h35m,-5d00m) の PSF@345GHz

コントアは 0.05(5%) 刻み

5 minutes integration 8 　 hours integration

• beamFWHM(0.58”,0.69”)PA ～ -40deg

• side-lobe-6% ～ 20%

• 1σ sensitivity (2GHz BW)0.79mJy (22.3mK)

• beamFWHM(0.62”,0.73”)PA ～ -60deg

• side-lobe-6% ～ 8%

• 1σ sensitivity (2GHz BW)0.080mJy (2.03mK)

EA PS Report 142nd ALMA Users Meeting 2011/1/13

-Oph. (16h25m,-25d00m) の PSF@345GHz

コントアは 0.05(5%) 刻み

5 minutes integration 8 　 hours integration

• beamFWHM(0.58”,0.65”)PA ～ -40deg

• side-lobe-6% ～ 20%

• 1σ sensitivity (2GHz BW)0.78mJy (23.3mK)

• beamFWHM(0.58”,0.73”)PA ～ -75deg

• side-lobe-6% ～ 8%

• 1σ sensitivity (2GHz BW)0.079mJy (2.70mK)

EA PS Report 152nd ALMA Users Meeting 2011/1/13

Lupus (15h40m,-35d00m) の PSF@345GHz

コントアは 0.05(5%) 刻み

5 minutes integration 8 　 hours integration

• beamFWHM(0.58”,0.65”)PA ～ -40deg

• side-lobe-6% ～ 20%

• 1σ sensitivity (2GHz BW)0.78mJy (23.5mK)

• beamFWHM(0.58”,0.73”)PA ～ -75deg

• side-lobe-6% ～ 6%

• 1σ sensitivity (2GHz BW)0.080mJy (2.14mK)

EA PS Report 162nd ALMA Users Meeting 2011/1/13

Chameleon (15h40m,-70d00m) の PSF@345GHz

コントアは 0.05(5%) 刻み

5 minutes integration 8 　 hours integration

• beamFWHM(0.62”,0.88”)PA ～ -30deg

• side-lobe-6% ～ 20%

• 1σ sensitivity (2GHz BW)0.86mJy (17.9mK)

• beamFWHM(0.73”,0.73”)PA ～ -75deg

• side-lobe-4% ～ 4%

• 1σ sensitivity (2GHz BW)0.088mJy (1.86mK)

EA PS Report 172nd ALMA Users Meeting 2011/1/13

Gallery1

EA PS Report 2nd ALMA Users Meeting 2011/1/13 18

This is an object in our own galaxy. It is a young star which is still surrounded by a disc of gas. Here we are observing the carbon monoxide J = 3-2 line at 345 GHz in the disc. (The star itself is not visible here.) The integrated flux is shown as contours on the left, while the spectrum at the peak of the emission is on the right, showing, via the Doppler effect, that the gas is moving at different speeds. In the middle is the average velocity of the gas at each point in the image, indicated by the colour. This shows a characteristic pattern created by the rotation of the disc around the star.

Gallery2

EA PS Report 2nd ALMA Users Meeting 2011/1/13 19

As a test of ALMA’s ability to observe broad spectral lines, we observed the quasar BRI 0952-0115, which is at a red-shift of z = 4.43. The object is again unresolved on short baselines, but the 158 micron line from ionized carbon is clearly detected in the spectrum, which is impressive given that this observation took only one hour in total.

Summary

• ALMA Early Science Cycle0 is coming soon with unprecedented sensitivity.

• Prepare for your proposal with understanding ALMA Cycle0 capability.

• Cycle0 final spec will be decided by Mid March.

• Join us in the ALMA special session on Mar 16th in the ASJ annual meeting in Tsukuba.

EA PS Report 2nd ALMA Users Meeting 2011/1/13 20

2nd ALMA Users Meeting 2011/1/13 2121

www.almaobservatory.org

The Atacama Large Millimeter/submillimeter Array (ALMA), an international astronomy facility, is a partnership among Europe, North America and East Asia in cooperation with the Republic of Chile. ALMA is funded in Europe by the European Organization for Astronomical Research in the Southern Hemisphere (ESO), in North America by the U.S. National Science Foundation (NSF) in cooperation with the National Research Council of Canada (NRC) and the National Science Council of Taiwan (NSC) and in Japan by the National Institutes of Natural Sciences (NINS) in cooperation with the Academia Sinica (AS) in Taiwan. ALMA construction and operations are led on behalf of Europe by ESO, on behalf of North America by the National Radio Astronomy Observatory (NRAO), which is managed by Associated Universities, Inc. (AUI) and on behalf of East Asia by the National Astronomical Observatory of Japan (NAOJ). The Joint ALMA Observatory (JAO) provides the unified leadership and management of the construction, commissioning and operation of ALMA..

EA PS Report