ALMA: Capabilities and Status

1. ALMA: Capabilities and Status Al Wootten NRAO, ALMA/NA Project Scientist

2. Who is ALMA? • ALMA is governed by a Board, with representatives from each of the partners (Chile, NSF/NRC, ESO/Spain, NINS) [~10 folks+] • Board committees include ALMA Science Advisory Committee (ASAC) [~14 folks], AMAC • ALMA construction activities are conducted by joint teams which report to the Joint ALMA Office (Tarenghi, Director; Beasley, Project Manager) in Santiago [four+] • Regional Managers, Project Scientists, Advisory Committees (e.g. NA, EU, JP ALMA Project Manager) ; • ANASAC, ESAC, JSAC • Regional ALMA Resource Centers (ARCs) in partner regions support users in the respective astronomical communities [NAOJ, NRAO, ESO]

3. ALMA Observes the Millimeter Spectrum COBE observations • Millimeter/submillimeter photons are the most abundant photons in the cosmic background, and in the spectrum of the Milky Way and most spiral galaxies. • Most important component is the 3K Cosmic Microwave Background (CMB) • After the CMB, the strongest component is the submm/FIR component, which carries most of the remaining radiative energy in the Universe, and 40% of that in for instance the Milky Way Galaxy. • ALMA range--wavelengths from 1cm to 0.3 mm, covers both components to the extent the atmosphere of the Earth allows.

4. Summary of existing and future mm/sub-mm arrays Telescope altitude diam. No. A nmax (feet) (m) dishes (m2) (GHz) NMA 2,000 10 6 470 250 CARMA 7,300 3.5/6/10 23 800 250 IRAM PdB 8,000 15 6 1060 250 SMA 13,600 6 8 230 690 eSMA 13,600 6/10/15 10 490 690 ALMA 16,400 12 50 5700 950 ACA 16,400 7 12 460 950 ALMA will have >6x more collecting area, and will be 10-100 times more sensitive and 10-100 times better angular resolution compared to current mm/submm telescopes

5. Contributors to the Millimeter Spectrum Spectrum courtesy B. Turner (NRAO) • In addition to dominating the spectrum of the distant Universe, millimeter/submillimeter spectral components dominate the spectrum of planets, young stars, many distant galaxies. • Cool objects tend to be extended, hence ALMA’s mandate to image with high sensitivity, recovering all of an object’s emitted flux at the frequency of interest. • Most of the observed transitions of the 142 known interstellar molecules lie in the mm/submm spectral region—here some 17,000 lines are seen in a small portion of the spectrum at 2mm. • However, molecules in the Earth’s atmosphere inhibit our study of many of these molecules. Furthermore, the long wavelength requires large aperture for high resolution, unachievable from space. To explore the submillimeter spectrum, a telescope should be placed at Earth’s highest dryest site.

6. Forests of Spectral Lines Schilke et al. (2000)

7. Where is ALMA? Toco AOS TB Chajnantor Negro Chascón Road Macón OSF Honar 43km=27 miles El llano de Chajnantor N

8. 5000m Chajnantor site APEX CBI ALMA Site Char

9. Transparent Site Allows Complete Spectral Coverage • 10 Frequency bands coincident with atmospheric windows have been defined. • Bands 3 (3mm), 6 (1mm), 7 (.85mm) and 9 (.45mm) will be available from the start. • Bands 4 (2mm), 8 (.65mm) and, later, some 10 (.35mm), built by Japan, also available. • Some band 5 (1.5mm) receivers built with EU funding. Pwv = 0.5mm 15% of time

10. Receivers/Front Ends • 183 GHz water vapour radiometer: • Used for atmospheric path length correction • Dual, linear polarization channels: • Increased sensitivity • Measurement of 4 Stokes parameters

11. Antennas • Demanding ALMA antenna specifications: • Surface accuracy (25 µm) • Absolute and offset pointing accuracy (2 arcsec absolute, 0.6 arcsec offset) • Fast switching (1.5 deg sky in 1.5 sec) • Path length (15 µm non-repeatable, 20 µm repeatable) • To validate these specifications: two prototype antennas built & evaluated at ATF (VLA)

12. Prototype Antenna Testing at VLA Photogrammetry, January 2005

13. Antenna Configurations (min) 150 m

14. ALMA + ACA First ACA 12m – Dec 2007, 7m – Nov 2008

15. Big tractor picture These vehicles must lift the 110 ton antenna systems and transport them over the ALMA road, often for several tens of kilometers at 7% avg grade, to and from the antenna stations and the OSF. To do this, these vehicles are equipped with twin 1340 horsepower engines; the transporters measure 33 feet wide, 52 feet long, and 15 feet high.

16. Antenna Configurations (max) 10,000m 4 mas @ 950 GHz Site infrastructure (AOS/OSF) + inner array completed 2008

17. Summary of detailed requirements

18. Schedule

19. NOT YET BOARD APPROVED 2008 2009 2006 2007 2010 2011 2012 1 2 3 4 1 2 3 4 1 2 3 4 1 2 3 4 1 2 3 4 1 2 3 4 1 2 3 4 Time Now Projected Science Summary Schedule (Data as of 2006Aug06) ATF Testing Nov ’06 ATF First Fringes SE&I Reference OSF Integration – Start dates 50th 32nd 1st 2nd 3rd 8th 16th ATF Testing Support ATF Site Characterization Science Support OSF Commissioning Antenna Array – Finish dates SCIENCE SUMMARY ` 32nd 3rd 8th 16th 50th March ’09 Limited call for SV proposals +6 antennas Science Verification OSF/AOS Sept ’09 Early Science Decision Point Evaluation of Early Science Array Complete Call for Proposals / Early Science Preparation July ’10 Early Science (+24) Sept ’12 Start of Full Science

20. Highest Level Science Goals Bilateral Agreement Annex B: “ALMA has three level-1 science requirements: • The ability to detect spectral line emission from CO or C+ in a normal galaxy like the Milky Way at a redshift of z = 3, in less than 24 hours of observation. • The ability to image the gas kinematics in a solar-mass protostellar/ protoplanetary disk at a distance of 150 pc (roughly, the distance of the star-forming clouds in Ophiuchus or Corona Australis), enabling one to study the physical, chemical, and magnetic field structure of the disk and to detect the tidal gaps created by planets undergoing formation. • The ability to provide precise images at an angular resolution of 0.1". Here the term precise image means accurately representing the sky brightness at all points where the brightness is greater than 0.1% of the peak image brightness. This requirement applies to all sources visible to ALMA that transit at an elevation greater than 20 degrees. These requirements drive the technical specifications of ALMA. “ A detailed discussion of them may be found in the new ESA publication Dusty and Molecular Universeon ALMA and Herschel.

21. ALMA Design Reference Science Plan(DRSP) • Goal: To provide a prototype suite of high-priority ALMA projects that could be carried out in ~3 yr of full ALMA operations • Started planning late April 2003; outline + teams complete early July; submitted December 2003; updated periodically • 128 submissions received involving ~75 astronomers • Review by ASAC members completed; comments included • Current version of DRSP on Website at: http://www.strw.leidenuniv.nl/~alma/drsp.html New submissions continue to be added.

22. Frequency band capabilities • Band 3: 84-116GHz. FOV = 60 arcsec • Continuum: ff/dust separation, optically-thin dust, dust emissivity index, grain size • SiO maser, low excitation lines CO 1-0 (5.5K), CS 2-1, HCO+ 1-0, N2H+… • Band 6: 211-275GHz. FOV = 25 arcsec • Dust SED • Medium excitation lines: CO 2-1 (16K), HCN 3-2, … • Band 7: 275-373GHz. FOV = 18 arcsec • Continuum: most sensitive band for dust. • Wave plate at 345GHz for precision polarimetry • Medium-high excitation lines: CO 3-2 (33K), HCN 4-3, N2D+, … • Band 9: 602-720GHz. FOV = 9 arcsec • Towards peak of dust SED, away from Rayleigh Jeans; hence T(dust) • High excitation lines e.g. CO 6-5 (115K), HCN 8-7 in compact regions

23. Aperture Synthesis with ALMA 12-m cross-correlations from 60 dishes measure spacings from 12m up to maximum baseline e.g. 10km Auto-correlations from 4 12-m dishes measure from zero up to ~6m spacings 12m • Extra measurements here help imaging precision: • Cross-correlations from 7-m dishes, or • Large single dish observations Up to 15km

24. Initial Conditions: Pre-collapse Cores • Strong chemical gradients and clumpiness • Indicates depletion and chemical evolution • ALMA mosaic at 3mm: 100 pointings plus single-dish data needed • ALMA can resolve 15AU scales in nearby cores, or study cores at 1000AU scales out to 10kpc L1498: Tafalla et al.

25. Core dynamics: infall Small-scale Extended 0.1 - 0.3 pc Walsh et al Di Francesco et al (2001)

26. Starless Core Chemistry: probing the depletion zones • Complete CNO depletion within 2500AU? • ALMA can study this region, in objects as far as the GC, in H2D+ CS, CO, HCO+ NH3, N2H+ H2D+ D2H+ 2,500AU 8,000AU 372GHz line 15,000AU Walmsley et al. 2004; Caselli et al 2003

27. Polarized CO Line Emission • NFC1333IRAS4A • Goldreich-Kylafis Effect SiO J=1-0 Choi 2005 Girart, Crutcher, Rao 1999 A2 A1

28. Polarization and the Role of Magnetic Fields • Contours - I • Pixel - polarized flux density sqrt(Q^2+U^2) • RMS = 3 mJy/bm • Peak pol = 9 % at PA 153 degrees • At the peak of Stokes I - pol = 1% • Averaged pol = 4.7% @ 145 degrees E-Vectors • Polarization hole • Polarization peak is offset • Hour glass shape of the magnetic field structure in the circumbinary envelope • The large scale field is well aligned with the minor axis • We will need some higher angular resolution observations to map the structure of the field between the two cores Girart, Rao, Marrone 2006 The data indicate that, in the case of IRAS 4A, magnetic pressure is more influential than turbulence in slowing star formation within the cloud core. The same likely is true for similar cloud cores elsewhere. B-Vectors

29. Star formation in crowded environments • ALMA can resolve 15AU scales at Taurus • Clump mass function down to 0.1 Jupiter masses • Onset of multiplicity • BD formation • Internal structure of clumps • Turbulence on AU scales Bate 2002 Protostars and Clumps in Perseus: Hatchell et al 2005.

30. Cores and Filaments: Are Hydrodynamical Simulations Realistic? Motte et al • Clump mass spectrum • Relation to IMF? • Low mass limit? • Dependence on age? • Clump structure – transient or bound? • Filaments • are they omnipresent? • thermal/density structure Klessen 2004

31. Molecular Outflows Chandler & Richer 1999 • Origin of flows down to 1.5AU scales • 10 mas resolution at 345 GHz: • 24 hours gives 5K rms at 20 km/s resolution • Resolve magnetosphere: X or disk winds? • Flow rotation? • Proper motions • 0.2 arcsec per year for 100km/s at 100pc • Resolve the cooling length • Resolve multiple outflow regions 170AU resolution Beuther et al, 2002

32. Spatially-resolved Spectral Surveys 8GHz bandwidth Kuan et al 2004 Schilke et al

33. “Hot Core” chemistry around low mass protostars • 300AU sized molecular structures around protostellar candidates • Different chemical signatures Looney et al, 2000 Kuan et al 2004

34. Mplanet / Mstar = 0.5MJup / 1.0 Msun Orbital radius: 5 AU Disk mass as in the circumstellar disk as around the Butterfly Star in Taurus Maximum baseline: 10km, tint=8h, 30deg phase noise pointing eror 0.6“ Tsys = 1200K (333mu) / 220K (870mu) Sebastian Wolf (2005) l = 333mm l = 870mm 50 pc 100 pc 50 pc

35. “Debris” disk spectroscopy with Spitzer Rieke et al 2004

36. “Debris” Disk imaging with ALMA Fomalhaut (Greaves et al) • Wyatt (2004) model: dust trapped in resonances by migrating planets in disk • ALMA will revolutionise studies of the large cold grains in other planetary systems Vega (Holland et al)

37. Science group suggestions: * predictions about how gas lifts off of the surface of the disk and what the physical conditions of that gas might be - we need to know what tracers ALMA can use are likely to probe this effect and how those tracers are likely to evolve as the protostar heats up or for higher luminosity protostars. * when the material accretes from the "envelope" to the disk and starts to "pile-up” in the disk (in the scenario for episodic accretion), there should be a second, lower energy accretion shock in the outer disk. What are the atomic/molecular/continuum diagnostic of that shock? Any chance we could observe it with ALMA?

38. www.alma.info 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.