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ALMA Extended Array

ALMA Extended Array. Thermal Universe with a VLBI resolution. Seiji Kameno (Joint ALMA Observatory） Naomasa Nakai (Tsukuba U.) Yoichi Takeda, Kiyoto Shibasaki, Mareki Honma, Tomoya Hirota (NAOJ) Yoichi Tamura (IoA Tokyo U.). Calama. 7 stations in 300-km range. ALMA-AOS. ALMA-OSF.

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ALMA Extended Array

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  1. ALMA Extended Array Thermal Universe with a VLBI resolution Seiji Kameno (Joint ALMA Observatory）Naomasa Nakai (Tsukuba U.) Yoichi Takeda, Kiyoto Shibasaki, Mareki Honma, Tomoya Hirota (NAOJ) Yoichi Tamura (IoA Tokyo U.) Calama 7 stations in 300-km range ALMA-AOS ALMA-OSF Llama-SAC Zaldívar Llama-Macon Llullaillaco

  2. ALMA extened array VLBI resolution for Thermal emission Precise images than ALMA New parameter space (e.g. stellar images) ALMA extended array, compared w/ ALMA and VLBI ALMA 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 for non-thermal sources

  3. Thermal universe w/ VLBI resolution • 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) Essential point of the ALMA extended array Baseline-to-aperture ratio = aperture filling factor 300-km baseline is the upper limit for detecting thermal emission

  4. Array config. Thermal Universe with a VLBI resolution 300-km baseline is the upper limit for detecting thermal emission Calama 7 stations in 300-km range ALMA-AOS ALMA-OSF Zaldívar Llama-SAC Llama-Macon Llullaillaco • 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

  5. AOS - OSF 24-km interferometry

  6. Thermal Universe with a VLBI resolution Science Case 1 Super massive black holes : formation and fueling

  7. Science highlights : Black Holes Supermassive Black Holes (SMBHs) in galaxies Sub-mm galaxies discovered with ASTE (Tamura+09 Nature, 459, 61) • 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 Evolving BH in a galaxy (artist’s impression) SED of SgrA* RIAF disk (Yuan+03 ApJ, 598, 301) • 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）

  8. Mass accretion processes from galactic disk onto SMBH How does matter lose angular momentum? What is the source: Stars, Gas, or Dust? Galactic rotation ↓ BH-bound rotation in 1-10 pc Cen A w/ SMA : Espada+09, ApJ, 695, 116 Spatial resolution imaged by AeA 福江純「輝くブラックホール 降着円盤」p.162

  9. Imaging dust torus (土居2012:AEA workshop)

  10. Approaching the central engine of AGNs 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 Black-hole positioning by multifrequency core-position offset (Hada+11, Nature, 477, 185) Simulation images : Nagakura & Takahashi (2010)

  11. Thermal Universe with a VLBI resolution Science Case 2 Stellar imaging and size measurements

  12. Science highlights : Stars Stellar physics Betelgeuse NIR image (10-mas resolution) (Kervella+09, A&A, 504, 115) NIR visibilities • 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 The sun imaged with the Nobeyama Radio Heliograph (180 x 180 pixel) comparable w/ the sun Betelgeuse H-band image (9-mas resolution) (Haubois+09, A&A, 508, 923)

  13. ALMA stellar imaging Size measurements (photosphere imaging) of nearby Giants • Stellar apparent diameter • Flux density Antares (700 R8, 175 pc) → 40 mas e.g. 3000 K, 300 R8@ 1 kpc → 7 mJy → 7σ detection requires 30-min integ. w/ ALMA Stellar Radio Astronomy • to bring • stellar imaging capability • size measurements • distance estimation ← 60μJy without ALMA 3σ@3600 sec ← 6μJy 3σ@3600 sec

  14. Stellar size measurements Imaging giants@1 kpc Size measuring giants@10 kpc, main sequence@70pc M dwarf @ 10 pc can be measured to determine its mass Distance determination without annual parallax Size measurement of aM dwarf star if we can estimate the linear size - toward Galactic Center - more than 20,000 sources ← 6μJy 3σ@3600 sec

  15. Science 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 500 supergiants for phase 1 • 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

  16. AEA workshop on Nov. 2012 http://milkyway.sci.kagoshima-u.ac.jp/groups/workshopalmaextendedarray2012/ Early Universe / AGN Requirements for better Tb (~ 100 K) sensitivity • thermal emission from dust torus • counter / diffuse jets → shorter baseline (up to 100 km) Steller imaging Requirements for better resolution : θ ~ 0.3 mas • main sequence stars • convection cells • transit of planets • Longer baseline (~600 km) • Shorter wavelengths (~650 GHz) • Increase # of stations? Feedbacks from science requirements are welcome!

  17. Requirements Specifications RX / Backends Site survey Antenna Tests Infrastructure Technical development Full Op. Summary : AEA = ALMA sensitivity + VLBI resolution Site candidates (need survey) • 12 m (ALMA design) x 5 antennas • BW 16 GHz (4 GHz x 2SB x Dual pol.) • Baseline 300 km Schedule Cost total ~ $100M

  18. Technical 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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