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)


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


AOS - OSF 24-km interferometry AOS - OSF 24-km interferometry

Science Case 1

Super massive black holes : formation and fueling



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


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



/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


/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


/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


/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


/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


/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

Documents

ALMA Extended Array