alma extended array
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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)
ALMA Extended Array : EA ALMA Development Workshop 2013 July 9 3 /18
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)
ALMA Extended Array : EA ALMA Development Workshop 2013 July 9 10
/18
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
ALMA Extended Array : EA ALMA Development Workshop 2013 July 9 13
/18
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
ALMA Extended Array : EA ALMA Development Workshop 2013 July 9 14
/18
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
ALMA Extended Array : EA ALMA Development Workshop 2013 July 9 15
/18
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
ALMA Extended Array : EA ALMA Development Workshop 2013 July 9 16
/18
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
ALMA Extended Array : EA ALMA Development Workshop 2013 July 9 17
/18
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
ALMA Extended Array : EA ALMA Development Workshop 2013 July 9 19
/18
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
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