ACA; Atacama Compact Array

Transcription

1 ACA; Atacama Compact Array Ryohei Kawabe, ALMA-J Project Scientist & East Asian ARC Manager ALMA-J Office NAOJ 1

2 Array Configuration of ALMA 12-m Array ACA The ACA System 7m Array; Twelve (12) 7-meter diameter antennas (18 stations) TP Array; Four (4) 12-meter diameter antennas (4 stations) ACA FE; almost same FE as that in 12-m Array ACA Correlator in AOS building; Data compatible to 12-m Array data 2

3 Scientific Importance 1. Imaging Cold Universe with Thermal Emission - Usually extended in nature (over the primary beam of the 12m Array) - Quantitative studies using such emission needs complete spatial frequency data; ACA inclusion can do this - Imaging without missing key information leads to accurate interpretation for both experts and non-experts (novice users), and ACA contributes to the easy-to-use of ALMA. 3

4 Scientific Importance 2. Imaging at Sub-millimeter wavelength - Thermal emissions are still extended, although some are getting more compact - Primary Beam of the 12m antenna is getting smaller, and Pointing error will be more critical for wide field mosaicing 6 arcsec at 950 GHz 0.6 pointing accuracy (1/10 of the beam) ACA 7m antennas with larger FOV & TP array can help - Time window is very narrow at shorter sub-millimeter wavelengths even at Atacama site, and stand-by ACA array as sub-mm imager through whole year can enhance the sub-mm capability of the ALMA 4

5 12m array cannot sample shoter uv-data for uv distance (spatial frequency) < 15 m TP array samples 0-6 m data Both 12m array + TP array work perfectly for wide-field mosaic under no pointing error condition, but do not actually 7m array samples 6-15 m data ACA TP Array 12m array UV Sensitivity UV Response ACA 7m Array 5

6 Image Fidelity Improved by ACA Simulation (Tsutsumi et al. ) on line ratio image Results of simulation 12m Array 12m Array 6

7 Operation Modes of ACA and Roles in ALMA Mode 1 (primary) : Supplement the 12-m array data with Short baseline data (7-m antennas) Total power data (12-m antennas) Usually 12m array and ACA is Not electrically combined Common source is non-concurrently observed with 12m Array and ACA Enhance fidelity of ALMA images for extended sources (overcome missing-flux problem) Mode 2 : Stand-alone mode of operation Available for target-of-opportunity observations, wide-field surveys, etc. Mode 3 : Combined array with the 12-m Array antennas Short baseline data (7-m antennas) (+TP array for calib.) Correlate 12m Array and ACA (with BL-Correlator) Enhanced calibration accuracy ultimate sensitivity with ALMA; improved by factor of about 15 % ; equivalent to adding eight 12m antennas to 12m Array 7

8 Location & Configuration of ACA Location of ACA m north of 12 array center (as close as possible) TP Array ACA Configuration 7m Array 1) 7m array - two configurations Normal configuration; for high elevation sources NS extension; moves 3 ants to North 3 ants to South for low elevation sources (to avoid shadowing effect) N 12m Array Compact configuration 2) TP Array (with WVR) - surrounding 7m array for calibration of atmospheric phase gradient using WVR 8

9 ACA Operation Scenario; Long-term (tentative!) 12-m Array C1 config ACA Y+ Long-term coordination needed 12m A + ACA 9 months Time 12m A only 12-m Array executes common program in narrow time window But ACA mostly always (except for Stand-alone & combined Array) To minimize the time lag between observations with the two arrays To minimize the variation of the source & Observing condition 9

10 ACA Operation Scenario;short-term 7-m Array TP Array 12-m Calibration as common mode ~300 sec Interferometry at target source/freq. Single-dish at target source/freq. Time Interferometry on calib. source Interferometry on calib. source 7-m interferometry Multi-field mosaic 12-m single-dish Cal source within <4 deg from target Pointing/phase (Band 3) Bandpass/relative phase between Bands (less frequent) Beam switching On-the-fly (OTF) mapping 10

11 Total Power Observations with TP Array Observing Modes for Single-Dish Data Taking Source Size Continuum Spectral Line Point or Small -Beam Switch -Slow OTF with -Beam Swith -Slow OTF with wobbling -Slow OTF with Large (> a few beam) wobbling -Fast OTF wobbling -Slow OTF (with freq. SW) 11

12 Science Operation & End to End Services ACA and the 12 array will be operated in a coordinated way ACA necessity Checker & ACA sensitivity Calculator for Proposal Preparation Pipeline Software to handle both 12-m Array and ACA data and to make image 12

13 ACA Science Use Cases Imaging both disk + infalling envelope; Envelope sizes are AU (7-70 arcsec) Debris disks found around nearby young main sequence stars at d = 3 20 pc Polarization Imaging; ACA inclusion is expected to dramatically improve the fidelity for pol. Wide fileld imaging Sunyaev-Zel dovich effects in cluster of galaxies at mm & su-mm Wide-field Imaging of nearby galaxies; CO, [CI], & dust for understanding of overall star formation 13

14 Circumstellar Disk + Envelope ; ACA Imaging Simulations Model 10 K 20 acsec Gaussian = Envelope 12-m Array only 7-m Array only Fidelity ~ 1 (100 % Error) Fidelity ~ 1 10 arcsec 50 K, 5 arcsec = Disk Gaussian (10 K, 20 arcsec) + Gaussian (50 K, 5 arcsec) [Envelope] 1.4 x 1.3 arcsec [Disk] 7.0 x 5.5 arcsec 12-m Array + TP ACA ALL Fidelity ~ 15 Fidelity ~ 60 Fidelity ~ x 1.3 arcsec with ALMA 7.3 x Science 5.9 arcsec 1.4 x 1.3 arcsec 14

15 Example; Debris Disks Debris disks ; Rich in information on planet formation Usually larger than the primary beam of the 12m Array; i.e., arcsec. ACA helps for imaging and also detection of such extended & faint objects 15

16 ACA Simulation; εeridani (T. Sekiguchi & S. Takakuwa) ε ERIDANI Debris Disk Model (JCMT SCUBA) 1 2-m Array only dist ance of 1 3 pc 1 2- m Array + TP 1 2-m Array + ACA Greaves et al Fidelit ies Fidelity = Model Model - Simulation RA Off ( arcsec) 7-m Array can help very much 16

17 Simulations Using the 12m Array Alone Model Simulated Image Model - Simulated Image Fidelity Log (Fidelity) Deep negatives seen around the two galaxies arise from the incomplete sampling of the short spatial frequencies 17

18 Need ACA to recover short spatial frequencies Fourier Transform the difference image 18

19 Simulations with 12m Array + ACA Model Simulated Image Model - Simulated Image Fidelity The deep negatives surrounding the two galaxies have been recovered properly. The peak fidelity is 132 and has increased by factor of 2 from the image created using the 12m array alone. The mean fidelity (above 3) is 18, which is a 20% improvement from the simulation using the 12m array alone. 19

20 Image Fidelity Improved by ACA SZ Effect (Yamada, Tsutsumi, et al.) 90 ALMA (12m), Band 4 INPUT based on Most compact configuration 150GHz data (13 FWHM) 7 mosaics, 3 hrs total of RX J rms = 0.01 mjy/beam Expected signal + thermal noise = 0.09 mjy/beam ACA(7m), Band 4 4 mosaics, 12 hrs total rms = 0.1 mjy/beam peak = -1.3 mjy/beam 20

21 DRSP Statistics What is Design Reference Science Plan? - Collected high-priority ALMA projects which could be carried out in the first 3 years in the full operation - Reference for Science Oper. Plan, Imaging Simulation, Software design, any other application DRSP Initial Statistics for ACA 25% in NUMBER of observing proposals 41% in TIME of the 64-element array observations 21

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23 On the Combined Array (1) New Scope to enhance capability of ALMA (12m Array + ACA) Two Major Scientific Benefits - The combined array mode provide a % sensitivity improvement over the 12-m Array, benefiting ALMA science which targets deep and small fields. - The point source sensitivity of the ACA is improved by a factor of six when combined with the 12m array for calibration, improving the quality of calibration, decreasing the time necessary for calibration and allowing more on source observing tine (with out sacrificing 12m Array observing time) See Poster by Daisuke Iono for more details 23

24 On the Combined Array (2) How can manage both coordinated observations and combined mode? Recent Intensive Simulation to see proper ACA integ. Time (Shige Takakuwa & Daisuke Iono) - motivated by Ed Fomalont s suggestion that CA should be default mode because ACA integ. time needs not to be longer - The simulation results show that the same observing time seems to be sufficient for high fidelity imaging with 12m Array +ACA Combined Array as default mode might be an ideal future operation mode: resolve some concerns but be careful about actual implementation of operation modes (need more detailed analysis) - Operation is getting simpler - high performance without sacrificing ACA role and 12m Array observing time - might gain more observing time for ACA stand-alone mode 24

25 Schedule 2007 Q Q Q Q Q Q Q Q Q4 1st ACA 12-m antenna delivered at OSF ACA Correlator delivered at OSF Start commissioning of 1st ACA 12-m antenna (total power mode) 4th ACA 12-m antenna delivered at OSF 1st ACA 7-m antenna delivered at OSF Four ACA 12-m antennas commissioned and available for science verification At least one ACA 12-m antenna available for Early Science (total power mode/one element of 12-m array) 12th ACA 7-m antenna delivered at OSF ACA with 16 antennas commissioned Start full science operation including ACA 25

26 Recent highlights Antenna ACA 12-m Antenna #1 production in progress; pre-assembly starting Pre-assembly completed until the end of this year RX cabin Yoke OSF contractor s area being prepared (thanks to cooperation by NRAO) Base 26

27 Summary - ALMA enhanced by ACA allows quantitative study with high photometric accuracy even for extended sources -ACA helps for a variety of target sources at every receiver band; planet forming regions to high-z sources 27

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29 Special Note on Maximum fringe Spacing Gaussian distribution with FWHM same as the maximum fringe spacing is almost resolved out and only 3-4 % is sampled at the fringe spacing. If 90, 75, 50, 25 % of total flux is attempted to be sampled, the Gaussian distribution (FWHM) would be smaller than the fringe spacing by factors of 6.0, 3.4, 2.3, and 1.6 respectively. 29

30 Maximum Fringe Spacing FE Band Freq (GHz) 12m FWHM Beam (arcsec) Max. Fringe Spacing (*) 12m & 1.25 (arcsec) mFWHM Beam (arcsec) Max. Fringe Spacing 7m & 1.25 (arcsec) 30

31 Examples of ACA science use cases Scientific Justification for the ALMA Enhancements by ASAC (Oct. 15, 2001) 31

32 Importance of Additional Bands Baseline four bands & ALMA-J three bands can cover most of major atmospheric windows at mm & sub-mm wavelengths total 7 bands in planned 10 bands - cover basic molecular & atomic lines - achieve mostly continuous redshift coverage in CO, [CI], & [CII] lines; powerful for the study of high-z galaxies/universe - useful for ＳＥＤ determination 32

33 Importance of Additional Bands Band-10 ( up to 950 GHz) ;Highest Frequency Band of ALMA - Highest Spatial Resolution - Key Freq. Band for determination of SED redshift-estimation by radiometric SED (combining negative/positive K correc.) estimation of dust-opacity to see dust formation, dust size evolution, & nature of dust - Including one of [CI] lines, & Closest to [CII] line (158 μm) 33

34 Band-10 resolves disk 34

35 Importance of Additional Bands - Band-8; One of Important short Sub-mm bands Another [CI] line, & very useful for probing PDRs (Photo Dissociation Regions), & Molecular Cloud Forming Regions CO(4-3), redshifted [CII] Band-4;One of transparent Atmospheric windows - Very rich in Molecular lines & useful for astro-chemistry; CS(3-2), SiO(3-2), HCN(2-1), H2CO... - Extends redshift coverage of CO/[CI]/[CII] 35

36 Band-3, 6,7, &9 + Band-4,8, &10 Redshift Coverage for major spectral lines CII CI(2-1) CI(J=1-0) CO(J=1-0) Redshift 36

37 Summary - ALMA enhanced by ACA allows quantitative study with high photometric accuracy & helps for a variety of target sources; planet forming regions to high-z sources - Three receiver bands expand science capability of ALMA; covering wider redshift coverage & major molecular & atomic lines 37

38 2. ALMA-J Progress 38

39 Overview East Asia Science Advisory Committee Organized First face-to-face meeting in Tokyo on Oct JP members + 2 TW members Observers from China and Corea Recent Highlights New Building for development & Building refurbished for EA ARC Antenna Band 4, 8, and 10 ACA Front End Integration Center 39

40 Recent highlights Antenna ACA 12-m Antenna #1 production in progress; pre-assembly starting Pre-assembly completed until the end of this year RX cabin Yoke OSF contractor s area being prepared (thanks to cooperation by NRAO) Base 40

41 Recent highlights Band 4 and 8 Design refined for pre-production Evaluation ongoing Product Assurance procedure introduced (component procurement/inventory control) Band 10 Mixer development underway New member: Dr. Matthias Kroug for junction/mixer development Evaluation system set up ACA Front End Integration Center One of the major contributions from ASIAA in Taiwan 41

42 Specifications of New Receiver Bands TSSB Band RF range Mixer IF for All / 80% of RF range Band GHz 2SB 4-8 GHz 4 82 / 51 K Band GHz 2SB 4-8 GHz / 196 K Band GHz DSB 4-12 GHz / 230 K 42

43 Assembled Band 4 Pre-Production Cartridge 43

44 Band 8 Pre-Production Cartridge Design 44

45 Compliance Matrix of Band 8 Qualification Model C : Comply PC : Partially Comply Performance Specification Compliance Comments Cartridge noise performance < 8 hf/k (SSB) - 80 % C of bandwidth, < 12 hf/k (SSB) 100 % of bandwidth Image rejection ratio > 10 db PC > 9 db Cartridge IF output power (4-8 GHz : SSB) C IF ripple < 4.0 db/2 GHz PC Gain compression between 77 and 300 K < 5 %. C 2 ±1 % Amplitude stability 0.1 and 1 sec < 4.0 x 10^(-7) C < 2.0 x 10^(-7) Amplitude stability 100 sec < 8.0 x 10^(-5) C < 4 x 10^(-5) Signal Path Phase stability < 2.0 degree/5 minutes C < 2.0 degree / 5 RF beam efficiency > 90 % at the subreflector C > 92 % Polarization align. Accuracy < 2.0 degree C < 1 degree Cross-polarization < -20 db C < -28 db 45

46 Band 10 Cartridge Development Team New Team Leader: Dr. Y. Uzawa Instrument Sci.: Dr. Sergey Shitov Collaboration with ASIAA, PMO, NICT Mixer Development Parallel developments NbTiN vs. NbN Waveguide vs. Quasioptical Good mixer circuit design achieved Balanced mixer configuration Receiver Cartridge Design IF amplifier development ongoing Mechanical/thermal design ongoing LO development to be started 46

47 Band 10 Mixer Evaluation System in Mitaka NEL power amplifier Millitech x6 VDI tripler x tripler Band 10 LO development 0.10 NELamp+Multiplier: 828 GHz 295 K Current (ma) K Pumped Unpumped IF output power (a.u.) Bias voltage (mv) Example of a measurement 47

48 ACA Correlator Prototype Mother Card Contract Fujitsu Co. (2004 September) Design PDR passed in 2005 May Detailed design made Prototyping Prototype testing plan made Prototype cards being produced/tested Aim at CDR in 2006 November 48

49 The Atacama Large Millimeter Array (ALMA) is an international astronomy facility. ALMA is a partnership between Europe, North America and Japan, in cooperation with the Republic of Chile. ALMA is funded in North America by the U.S. National Science Foundation (NSF) in cooperation with the National Research Council of Canada (NRC), in Europe by the European Southern Observatory (ESO) and Spain. ALMA construction and operations are led on behalf of North America by the National Radio Astronomy Observatory (NRAO), which is managed by Associated Universities, Inc. (AUI), on behalf of Europe by ESO, and on behalf of Japan by the National Astronomical Observatory of Japan.

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51 Spain NRC NRC-NSF Agreement Bilateral ALMA Agreement Spain-ESO Agreement ESO NSF Enhanced ALMA Agreement NINS; National Institute for Natural Sciences NINS AS - NINS Agreement Signatories of Major Agreements Major Agreements NAOJ; belongs to NINS AS Regional Partners Regional Agreements 51