1. CARMA (Combined Array for Research in Millimeter Astronomy) Capabilities and Future Prospects Dick Plambeck SF/ISM Seminar, 9/5/2006

2. outline background capabilities what is CARMA good for? science example: does the clump mass spectrum in molecular clouds determine the IMF?

3. + UChicago SZA 8 3.5-m antennas Berkeley-Illinois-Maryland array 10 6.1-m diameter antennas Caltech array 6 10.4-m antennas CEDAR FLAT

4. Aug 2005Apr 2004 Cedar Flat

5. 21 Jul 2004 – lifting off the first reflector

9. panel adjustment surface error determined from holography before adjustment: 127 μm rms → 75% loss at 225 GHz after adjustment: 28 μm rms → 7% loss at 225 GHz

11. all antennas assembled 10 Aug 2005

12. 95 GHz continuum map of SS433 25 Aug 2006 25 Aug 2006 rms noise 0.6 mJy/beam

13. basics incoming signals accepted: 3mm 80-116 GHz 1mm 220-270 GHz downconverted (1-5 GHz), amplified signal sent to lab on optical fiber mostly noise from sky and receiver; source contributes < 10-3 cross-correlation spectrum correlator

14. tuning example LO1 tunable 85 -115 GHz, or 220 -270 GHz (1) receive 4 GHz wide bands above (USB) and below (LSB) LO1 (2) 8 independent spectrometers process (USB+LSB) (3) USB and LSB signals separated in each spectrometer 12CO 115.27 GHz13CO 110.20 GHz LO1 112.73 GHz (1) no 1mm band on OVRO yet; (2) currently 1.5 GHz for BIMA 3mm receivers; (3) currently only 2.5 sky freq BIMA, OVRO correlator sections

15. correlator (spectrometer) modes (for first 3 bands)

16. correlator modes (for remaining 5 bands)

17. 5 arrays (A,B,C,D,E) 57 pads for 15 telescopes

19. Cedar Flat E-array (most compact) synth beam 4.5" at 230 GHz Highway 168

20. D-array synth beam 1.8"

21. C-array synth beam 0.8"

22. B-array synth beam 0.32"

23. A-array synth beam 0.13"

24. a reminder: interferometer acts as a spatial filter

26. E-array BIMA antennas within collision range SZA provides even shorter spacings combine with single dish measurements from 10.4-m antennas

28. colliding antennas

30. what can we do now that we couldn’t do before? better site should allow routine observing at 1.3 mm much improved sensitivity (3 x collecting area of BIMA, 5 x instantaneous bandwidth) high dynamic range imaging owing to more baselines, hence better sampling of u,v plane

31. 225 GHz zenith opacity %taumm H2O SSB Tsys 25<.12<1.8<290 50<.16<2.4<350 75<.28<4.3<520 Tsys computed for 1.5 airmasses, Trcvr(DSB) = 45 K

33. sensitivity examples 5σ detection of dust continuum from.04 Mo clump at 300 pc (5 mJy at 230 GHz) 5σ detection of 1-0 CO emission from 2500 Mo cloud in M33 (2.5 K in 3’’ beam, ΔV = 2 km/sec) tauBWmins BIMA0.320.8 GHz3400 CARMA0.161.5 GHz100 CARMA0.164.0 GHz40 tauBWmins BIMA0.320.7 MHz470 CARMA0.270.7 MHz60

34. Comparison with other arrays CARMA + SZA SMAIRAMALMA elevation2200 m420025005000 antennas238650+ baselines25328151225+ diameter10, 6, 3.561512, 7 area850 m 2 22610605600+ max baseline 1900 m500 m400 m14 km

35. Comparison of u,v coverage 6 hr track on source at decl +10º OVRO E, 15 baselinesCARMA D, 105 baselines

36. Synthesized beams 5% contours

37. problems with poor u,v sampling missing Fourier components (u,v spacings) → an infinite number of maps are consistent with the data! how can we publish papers? sources with a few compact components are no problem CLEAN, max entropy methods are ways of interpolating/extrapolating based on our bias about the sources (e.g., sources consist of a few compact components).

38. CLEANed map, point source at center Tsys = 0; no atmospheric phase noise

39. CLEANed map, point source at center Tsys = 0; atmospheric phase noise 150 um at 100 m; 1% contours

40. extended source 12 x 6 arcsec FWHM, total flux 1 Jy integrated flux = 0.77 integrated flux = 0.006

41. scientific example what determines the IMF? physics of infall from disk to star –‘stars determine their own mass’ fragmentation of interstellar clouds –some (approximately fixed) percentage of a clump mass will find its way onto the star observational test: measure the mass spectrum of prestellar clumps –want ~ a few x 10 3 AU resolution, ~ 5-10’’ in nearby clouds –an example: Testi and Sargent 1998, OVRO mosaic of 5’x5’ region in Serpens

42. Serpens mosaic Testi & Sargent 1998 99 GHz continuum 5“ resolution, about 1500 AU noise level 0.9 mJy/beam 1σ contours beginning at +/- 3σ anything > 4.5 σ (4 mJy/beam) considered real strongest sources are ~100 mJy

43. cumulative mass spectrum of 26 clumps not associated with IR sources dotted line is best fitting power law, dN/dM ~ M -2.1 dashed line is Salpeter IMF, dN/dM ~ M -2.35 dash-dot line is power law characteristic of larger cores, dN/dM ~ M -1.7 (Williams, Blitz, McKee 1998) → mass spectrum of protostellar dust condensations closely resembles local IMF

44. strongest sources are ~100 mJy anything > 4 mJy/beam is considered real → need dynamic range of 25:1 synthesized beams are particularly ugly near declination 0

45. configurations, beam pattern for Serpens mosaic

46. comparison with BIMA mosaic Lowest contour 2.7 mJy/beam, peak ~105 mJy, beam 5" Lowest contour 8 mJy/beam, peak 256 mJy, beam ?

47. simulate: OVRO C,D,E

48. 2 sources (300 mJy and 12 mJy), no atmospheric phase fluctuations

49. same model, but include atmospheric phase fluctuations of 150 um on 100-m baseline

50. extended source in the field

51. CARMA D array

52. CARMA D

53. CARMA D array + SZA (23 antennas, 253 baselines)

54. CARMA DZ

55. summary accurate measurements of clump mass spectrum in complicated regions require not only high sensitivity, but also high dynamic range, image fidelity many antennas, ability to get close spacings are critical mosaicing many fields necessary to survey sufficiently large regions CARMA is an important step in this direction

56. 27 Mar 2004 groundbreaking

57. 17 Dec 2004 - generator building under construction

58. 16 Dec 2004 – fiberoptic conduits