ALMA Extended Array
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Transcript of ALMA Extended Array
ALMA Extended Array
Seiji Kameno (Joint ALMA Observatory )Naomasa Nakai (Tsukuba U.)Yoichi Takeda, Kiyoto Shibasaki, Mareki Honma, Tomoya Hirota (NAOJ)Yoichi Tamura (IoA Tokyo U.)
Thermal Universe with a VLBI resolution
7 stations in7 stations in300-km range300-km range
ALMA-AOSALMA-OSF
Calama
Zaldívar
Llullaillaco
Llama-Macon
Llama-SAC
ALMA Extended Array : EA ALMA Development Workshop 2013 July 9 2 /18
ALMA extended array, compared w/ ALMA and VLBIALMA extended array, compared w/ ALMA and VLBIALMA VLBI
• Dense array (10m - 15 km)• Tb sensitivity ~10 K• Resolution ~ 10 - 100 mas
• Long baseline (~1000 km)• Tb sensitivity ~108 K• Resolution ~ 0.1 - 1 mas
Targetting dark/cold unverse Extreme resolution fornon-thermal sources
ALMA extened array
VLBI resolution for Thermal emission
Precise images than ALMANew parameter space (e.g. stellar images)
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Essential point of the ALMA extended arrayEssential point of the ALMA extended array
•Stations : ~ 5 + 2 (from Llama)•Sensitivity : σ=2 μJy@3600 sec(20 μJy without ALMA)•Resolution : 0.6 mas•Tb detection limit : 5σ = 1000 K(3000 K without ALMA)
Thermal universe w/ VLBI resolution
300-km baseline is the upper limit fordetecting thermal emission
Baseline-to-aperture ratio= aperture filling factor
7 stations in7 stations in300-km range300-km range
ALMA-AOS
Array config. Thermal Universe with a VLBI resolution
SitesSites AltitudeAltitude LatitudeLatitude LongitudeLongitude Dist. from Dist. from ALMAALMA
AOSAOS 5000 -23.030 -67.755 0
OSFOSF 2900 -23.073 -67.980 24 km
CalamaCalama 3400 -22.706 -68.428 78 km
ZaldívarZaldívar 3300 -24.232 -68.893 177 km
LlullaillacoLlullaillaco 4000 -25.227 -69.040 277 km
Llama-SACLlama-SAC 4755 -24.228 -66.455 188 km
Llama-Llama-MaconMacon
4600 -24.675 -67.305 188 km
• Alt.> 3000 m for 350 GHz• Access roads• Baseline length : 24 - 300 km• (u, v) coverage : E-W and N-S direction• Llama project, preparing 2 stations in Argentine
ALMA-OSF
Calama
Zaldívar
Llullaillaco
Llama-Macon
Llama-SAC
300-km baseline is the upper limit fordetecting thermal emission
ALMA Extended Array : EA ALMA Development Workshop 2013 July 9 5 /18
AOS - OSF 24-km interferometry AOS - OSF 24-km interferometry
Science Case 1
Super massive black holes : formation and fueling
Thermal Universe with a VLBI resolution
ALMA Extended Array : EA ALMA Development Workshop 2013 July 9 7 /18
Science highlights : Black HolesScience highlights : Black Holes
Sub-mm galaxies discovered with ASTE(Tamura+09 Nature, 459, 61)
Supermassive Black Holes (SMBHs) in galaxies
• Sub-mm galaxies in the early Universe• Search for SMBHs in high-z galaxies
• Clarify Galaxy / SMBH co-evolution
• High resolution to discriminate AGN from SB
• BH engines in nearby AGNs• Mass accretion process from galactic disk to BH
• Census for RIAF at sub-mm SED peak
• Imaging BH+accretion disk( as a part of sub-mm VLBI)
Evolving BH in a galaxy (artist’s impression)
SED of SgrA* RIAF disk(Yuan+03 ApJ, 598, 301)
ALMA Extended Array : EA ALMA Development Workshop 2013 July 9 /18
Mass accretion processes from galactic disk onto SMBHMass accretion processes from galactic disk onto SMBH
福江純「輝くブラックホール 降着円盤」 p.162
What is the source: Stars, Gas, or Dust?
How does matter lose angular momentum?
Spatial resolution imaged by AeA
Galactic rotation↓BH-bound rotation
in 1-10 pc
Cen A w/ SMA : Espada+09, ApJ, 695, 116
ALMA Extended Array : EA ALMA Development Workshop 2013 July 9 9 /18
Imaging dust torusImaging dust torus ( 土居 2012:AEA workshop)
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Approaching the central engine of AGNsApproaching the central engine of AGNs
Black-hole positioning by multifrequency core-position offset (Hada+11, Nature, 477, 185)
Radio ‘photosphere’ of the jet …frequency dependent
Hi-Fi imaging at > 40 GHz• High frequency to see through jets
• High dynamic range to discriminate
the disk from jets
• Middle baseline (~ a few 100 km) to
fill (u, v) hole in sub-mm VLBI
Simulation images : Nagakura & Takahashi (2010)
Science Case 2
Stellar imaging and size measurements
Thermal Universe with a VLBI resolution
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Science highlights : StarsScience highlights : Stars
Stellar physics
Imaging photospheres of
nearby giants / supergiants
• 100 x 100 pixel images for
Betelgeuse and Antares
• Flares, Prominences, CME
• Convection cells / Dynamo
• Motion of active regions
• Long-term monitor for
magnetic inversion
Betelgeuse NIR image (10-mas resolution) (Kervella+09, A&A, 504, 115)
The sun imaged with the Nobeyama Radio Heliograph (180 x 180 pixel)
Betelgeuse H-band image (9-mas resolution) (Haubois+09, A&A, 508, 923)comparable w/ the sun
NIR visibilities
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ALMA stellar imagingALMA stellar imagingSize measurements (photosphere imaging) of nearby Giants
• Stellar apparent diameter
• Flux density
e.g. 3000 K, 300 R@ 1 kpc → 7 mJy → 7σ detection requires 30-min integ. w/ ALMA
Antares (700 R, 175 pc) → 40 mas
Stellar Radio Astronomy
← 6μJy3σ@3600 sec
← 60μJy without ALMA3σ@3600 sec
to bring •stellar imaging capability•size measurements•distance estimation
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Stellar size measurementsStellar size measurements
Size measurement of aM dwarf star
← 6μJy3σ@3600 sec
M dwarf @ 10 pc can be measured to determine its mass
Imaging giants@1 kpcSize measuring giants@10 kpc, main sequence@70pc
Distance determination without annual parallax
if we can estimate the linear size
- toward Galactic Center- more than 20,000 sources
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Science goals of stellar size / imagingScience goals of stellar size / imaging
• Science goals : phase 1• 500 supergiants to be imaged (δ < 20º, K < 6 mag, lumi. class I and II)
• 1-hour / source → 500 hours
• Verify previously measured size and distance
• Establish size-spectral type-luminosity relation
• Surface activity (flares, spots, convection cells)
• Binary systems
• Science goals : phase 2• 20000 giants (δ < 20º, lumi. class III)
• 4 sources / hour → 5000 hours
• Angular diameter → distance
• Precise galactic structure and dynamics
beyond the center (NA w/ GAIA)
• Whole lifecycle of stars
• BH mass accretion by stellar dynamics
500 supergiants for phase 1
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AEA workshop on Nov. 2012AEA workshop on Nov. 2012
Early Universe / AGN
Requirements for better Tb (~ 100 K) sensitivity
→ shorter baseline (up to 100 km)
Steller imaging
Requirements for better resolution : θ ~ 0.3 mas
• Longer baseline (~600 km)• Shorter wavelengths (~650 GHz)• Increase # of stations?
Feedbacks from science requirements are welcome!
•thermal emission from dust torus•counter / diffuse jets
•main sequence stars•convection cells•transit of planets
http://milkyway.sci.kagoshima-u.ac.jp/groups/workshopalmaextendedarray2012/
ALMA Extended Array : EA ALMA Development Workshop 2013 July 9 /18
Summary : AEA = ALMA sensitivity + VLBI resolutionSummary : AEA = ALMA sensitivity + VLBI resolutionRequirements
ScheduleSchedule
CostCostFY X X+1 X+2 X+3 X+4 X+5 X+6…
survey
const-ruction
oper.
Site survey
Technical development
Infrastructure
Antenna
RX / Backends
Tests
Full Op.
•12 m (ALMA design) x 5 antennas12 m (ALMA design) x 5 antennas•BW 16 GHz (4 GHz x 2SB x Dual pol.)BW 16 GHz (4 GHz x 2SB x Dual pol.)•Baseline 300 kmBaseline 300 km
Bands 350 GHz (230 GHz, 650 GHz)
Resolution 0.6 mas
Image sensitivity 7σ = 10 μJy (1 hr)
Tb sensitivity 7σ = 1000 K (1 hr)
Site candidates (need survey)
Specifications
total ~ $100M
Stations¥ 1970 M/ant×5 = ¥ 9850 Msite 150 M, ant 1400 M, FE 300 M, BE 120 M
Computing ¥ 200 M
Tests ¥ 600 M
Managements
¥ 200 M
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Technical IssuesTechnical Issues
• Site survey ‣Higher altitude / sufficient (u, v) coverage
• Sub-mm coherence at long baselines‣LO distribution / individual frequency standards?‣Phase compensation : switching / VERA-like dual beam?
• Fiber connection‣ > 100 km optical fibre / VLBI recording?
• Correlator‣Number of baselines, faster phase tracking, larger delay buffer
• Calibration plan‣Are there good calibrators?
• Operation planning‣Impacts on ALMA
• Multi-Frequency Synthesis