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Maximum Aperture Telescope Workshop Organized by AURA Chaired by Jay Gallagher

MAX-AT Workshop Madison, Wisconsin, 27 - 29 August. Maximum Aperture Telescope Workshop Organized by AURA Chaired by Jay Gallagher. MAX-AT Workshop Madison, Wisconsin, 27 - 29 August. Basic Ideas for Very Large Aperture Telescopes the case for continuing groundbased astronomy. Matt Mountain

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Maximum Aperture Telescope Workshop Organized by AURA Chaired by Jay Gallagher

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  1. MAX-AT Workshop Madison, Wisconsin, 27 - 29 August Maximum Aperture Telescope WorkshopOrganized by AURAChaired by Jay Gallagher

  2. MAX-AT Workshop Madison, Wisconsin, 27 - 29 August Basic Ideas for Very Large Aperture Telescopesthe case for continuing groundbased astronomy Matt Mountain Gemini Telescopes August 1998

  3. Basic Ideas for Very Large Aperture Telescopesthe case for continuing groundbased astronomy • Goals • Establish a framework for discussing the science case for a Very or Extremely Large Aperture Telescope • Examine the challenges for 8m - 10m groundbased telescopes in an “NGST era” • Look at how a 21st Century groundbased telescope could extend and compliment the capabilities of an 8m NGST • Highlight some of the very real technical and cost-benefit challenges that have to be overcome • Make the case, that in an NGST era, with our current science interests, a groundbased 30m - 50m telescope is the necessary (if somewhat daunting) “next step”

  4. Science ? WHT UKIRT CFHT WIYN ARC TNG MPA KPNO IRTF NTT CTIO AAT ESO LBT 1 HET Keck 1 Keck 2 ORM Gemini N Subaru LBT 2 Gemini S MMT Palomar Magellan 1 Magellan 2 VLT 1 VLT 2 VLT 3 VLT 4 What is the case for a new groundbased facility? “Observing and understanding the origins and evolution of stars and planetary systems, of galaxies, and of the Universe itself.” - Gemini Science Requirements, 1990 Large collecting area and superb image quality and optimized IR performance

  5. Framework for a Science Case Where are our current science interests taking us?

  6. Adapted from Science, vol. 274, pg. 912 Lets be presumptuous…. - 21st Century astronomers should be uniquely positioned to study “the evolution of the universe in order to relate causally the physical conditions during the Big Bang to the development of RNA and DNA” (Giacconi, 1997) • Dynamics, abundances’ requires - spectral resolutions > 5,000 • Isolating individual objects or phenomena requires - high spatial resolution • Imaging spectroscopy at high spectral and spatial resolution requires - collecting area

  7. 10” Challenging 8m - 10m telescopes - Imaging Spectroscopy of the majority of objects in the HDF 4 mag.’s Current Keck spectroscopy limit HDF Differential Number counts from Williams et al 1996

  8. “Deconstructing High z Galaxies” Integral field observations of a z = 1.355 irregular HDF galaxy (Ellis et al) “Starformation histories of physically distinct components apparently vary - dynamical data is essential”

  9. Going beyond Gemini SN in Arp 220 (VLBI Harding et al 1998) 0.2” 0.4” ~ 0.01” 2” “milliarcsecond scale emission is common, perhaps universal in LIG’s”

  10. Beyond surveying M16 “pillars” for forming stars, closer inspection with NIRI reveals bipolar outflow Integral field spectroscopy reveals outflow dynamics Coronagraph reveals faint low mass companion AO+NIRS spectroscopy shows spectrum of a forming “super-Jupiter” “Deconstructing the M16 Pillars with Gemini” Embedded forming stars Approximate field of view of Gemini Mid Infrared Imager

  11. Log10 Fu (mJansky) x 30 Gemini 10 s, t = 10,000s R = 1800 l (mm) Going beyond Gemini Solar System @ 10 pc Jupiter 500 mas Gilmozzi et al (1998) Models for 1 MJ Planets at 10 pc from Burrows et al 1997

  12. How we will be competitive from the ground • The “Next Generation” Space Telescope (NGST) will probably launch 2006 - 2010 • an 6m - 8m telescope in space • NGST will be extremely competitive for: • deep infrared imaging, • spectroscopy at wavelengths longer than 3 microns • Groundbased telescopes can still compete in the optical and near-infrared • moderate to high resolution spectroscopy • Groundbased facilities can also exploit large baselines • high angular resolution observations

  13. Sensitivity gains for a 21st Century telescope For background or sky noise limited observations: S(Effective Collecting Area)1/2 . N Delivered Image Diameter  For background or sky noise limited spectroscopy: SEquivalent Telescope Diameter . N Effective Aperture Width  S/N x (106)1/2 • To meet these scientific challenges:S/N  30 x S/N of a 8m ~ 10 m Telescope

  14. Source noise background dark-current read-noise The gains of NGST compared to a groundbased 8m telescope • Assumptions (Gillett & Mountain 1998) • SNR = Is . t /N(t): t is restricted to 1,000s for NGST • Assume moderate AO to calculate Is • N(t) = (Is . t + Ibg. t + n . Idc + n . Nr2)1/2 • For spectroscopy in J, H & K assume “spectroscopic OH suppression” • When R < 5,000 SNR(R) = SNR(5000).(5000/R)1/2and 10% of the pixels are lost

  15. Photon-limited performance averaging OH lines Photon-limited performance between OH lines Relative Signal to Noise (SNR) of NGST/Gemini -- assuming a detected S/N of 10 for NGST on a point source, with 4000s integration Intermediate cases determined by detection noise 2 10 10 2

  16. Relative Signal to Noise (SNR) of NGST/Gemini -- assuming a detected S/N of 10 for NGST on a point source, with 4000s integration Spectroscopy between the OH lines 2 2

  17. Telescopes can still be competitive from the ground • NGST will be very competitive for: • deep infrared imaging, • spectroscopy at wavelengths longer than 3 microns • Groundbased telescopes can still compete in the optical and near-infrared • moderate to high resolution spectroscopy • Groundbased facilities can also exploit large baselines • high angular resolution observations The science case for groundbased “Maximum Aperture Telescope” must exploit the observational requirements for imaging spectroscopy, requiring: 1. High spatial resolution to isolate individual objects or phenomena 2. Moderate to high spectral resolution spectroscopy for dynamics and abundance measurements 3. An effective telescope diameter of ~ 50m to complement NGST (and the MMA) 10 milliarcsecond imaging spectroscopy to 28 - 30 magnitudes

  18. “its resolution stupid..” Facility Baseline Collecting Area (m) (m2) • Gemini 8-M 8 2 x 50 • CHARA 354 5.5 • Keck 1 & 2 + 165 157 + 11 • VLTI + 200 201 + 20

  19. “its resolution stupid..” Facility Baseline Collecting Area (m) (m2) • Gemini 8-M 8 2 x 50 • CHARA 354 5.5 • Keck 1 & 2 + 165 157 + 11 • VLTI + 200 201 + 20 • VLIA ~ 1000 800 (16 x 8m)Goal: 0.001 arcsecond images at 2.2 microns signal/noise gains ~ 10 compared to 8m telescopessensitivity gains ~ 102over Gemini for point like sources

  20. “its collecting area stupid..” Facility Baseline Collecting Area (m) (m2) • Gemini 8-M 8 2 x 50 • CHARA 354 5.5 • Keck 1 & 2 + 165 157 + 11 • VLTI + 200 201 + 20

  21. “its collecting area stupid..” Facility Baseline Collecting Area (m) (m2) • Gemini 8-M 8 2 x 50 • CHARA 354 5.5 • Keck 1 & 2 + 165 157 + 11 • VLTI + 200 201 + 20 • 20 m 20 316 • 50-M Telescope 50 1963Goal: 0.01 arcsecond images at 2.2 microns signal/noise gains ~ 30 compared to an 8msensitivity gains ~ 103 over Gemini for point like sources

  22. Modeled characteristics of 20m and 50m telescope Assumed point source size (mas) 20M 1.2mm 1.6mm 2.2mm 3.8mm 4.9mm 12mm 20mm (mas) 20 20 26 41 58 142 240 50M 1.2mm 1.6mm 2.2mm 3.8mm 4.9mm 12mm 20mm (mas) 10 10 10 17 23 57 94 h 70% 70% 50% 50% 50% 50% 50% Assumed detector characteristics 1mm < l < 5.5mm 5.5mm < l < 25mm Id Nr qe Id Nr qe 0.02 e/s 4e 80% 10 e/s 30e 40%

  23. Groundbased advantage NGST advantage Relative Signal to Noise Gain of groundbased 20m and 50m telescopes compared to NGST -- assuming a detected S/N of 10 for NGST on a point source, with 4x1000s integration

  24. Groundbased advantage NGST advantage Relative Signal to Noise Gain of groundbased 20m and 50m telescopes compared to NGST -- assuming a detected S/N of 10 for NGST on a point source, with 4x1000s integration

  25. “its sensitivity and resolution ..” Facility Baseline Collecting Area (m) (m2) • Gemini 8-M 8 2 x 50 • CHARA 354 5.5 • Keck 1 & 2 + 165 157 + 11 • VLTI + 200 201 + 20 • 20 m 20 316 • 50-M Telescope 50 1963Goal: 0.01 arcsecond images at 2.2 microns signal/noise gains ~ 30 - 60 over Geminisensitivity gains ~ 103 over Gemini for point like sources

  26. 50m Point Source Sensitivities10 s 10,000s

  27. 50m Point Source Sensitivities10 s 10,000s

  28. - and still a lot to understand Adaptive Optics will be essential Image profiles are Lorenzian 16 consecutive nights of adaptive optics the CFHT

  29. AO performance on a 50m Telescope Chun, 1998

  30. AO performance on a 50m Telescope • Diffraction limited imaging constrained to small field of view Chun, 1998

  31. The Challenge - Multiple Laser Beacons - still a lot of technologies to develop * * * * * * SRFA ~ 0.75 requires NBeacons 1.2mm 75 1.6mm 40 2.2mm 20 3.8mm 5 4.9mm 3 12.0mm <=1 20.0mm <=1

  32. Adaptive Optics will be essential Diffraction limited imaging will be constrained to small field of view How does this constrain the science?

  33. 8K x 8K array (3mas pixels) Imaging of the Universe at High Redshiftwith 10 milli-arcsecond resolution • Simulated NGST K band image • Blue for z = 0 - 3 • Green for z = 3 - 5 • Red for z = 5 - 10 •  = 0.1 Isoplanatic patch at 2.2 microns for 10mas imaging 48 arcseconds

  34. Going beyond Gemini SN Remnants in Arp 220 (VLBI Harding et al 1998) 0.2” 0.4” ~ 0.01” 2” “milliarcsecond scale emission is common, perhaps universal in LIG’s”

  35. Observations at z = 2 - 5 1 - 10 milli- arcseconds Velocity dispersion R= 105 104 103 102 101 Imaging Spectroscopy  10 AU Galactic observations out to 1kpc at 10 mas resolution Observation scale lengths 1 AU 1 R 100 AU 10 pc 100 pc 0.1 pc Accretion Disks Molecular Cloud Cores Mol. Outflows GMC Protoplanetary Disks AGN Jets/HH Planets Stellar Clusters

  36. Spectroscopic Imaging at 10 milli-arcsecond resolution - using NGST as “finder scope” • Simulated NGST K band image • Blue for z = 0 - 3 • Green for z = 3 - 5 • Red for z = 5 - 10 •  = 0.1 2K x 2K IFU 0.005” pixels l 48 arcseconds

  37. OWL OverWhelmingly Large 100-m diameter f/6.4 3 arc minutes FOV Spherical primary & secondary mirrors

  38. F/1 50m diameter parabolic primary (Oschmann 1996) 50 Meter Telescope Concept 50 m 2m diameter adaptive secondary producing collimated beam, with 1 arcmin. FOV

  39. 50 m Design Performance Concept: Parabolic segmented primary to simplify polishing and testing Primary mirror wind buffeting corrected by small 2m diameter adaptive secondary Collimated beam used to relay focus to 2m “telescopes” at both Nasmyth foci Diffraction limited performance across ~ 0.6 arcmin. FOV at = 2.2 microns

  40. Technology and “cost-benefit”challenges • Developing multi-laser beacon, high order adaptive optics or investigate atmospheric “tomography” • near-diffraction limited performance is at the heart of the MAX-AT science case • Choosing the most effective aperture • A 50m requires producing and polishing over 1,900 square meters of “glass” • equivalent to 39 Gemini’s or 25 Keck’s or over 20 HET’s • Deciding on which site or hemisphere…..

  41. “What can it cost?” • Primary mirror assembly $622M • Telescope structure & components $190M • Secondary mirror assembly $11M • Mauna Kea Site $78M • Enclosures $70M • Controls, software & communications $26M • Facility instrumentation (A&G, AO) $35M • Coating & cleaning facilities $9M • Handling equipment $5M • Project office $40MTotal $1,086M 50m Telescope costs (1997$) Scaled costs Constrained costs S (Keck + Gemini + ESO-VLT + Subaru) = $1,560M

  42. OWL OverWhelmingly Large Just to put things into perspective...

  43. A 400 year legacy of groundbased telescopes 0 The next step ? 50m telescope

  44. Basic Ideas for Very Large Aperture Telescopesthe case for continuing groundbased astronomy • Goals - recap • Establish a framework for discussing the science case for a Very or Extremely Large Aperture Telescope • Examine the challenges for 8m - 10m groundbased telescopes in an “NGST era” • Look at how a 21st Century groundbased telescope could extend and compliment the capabilities of an 8m NGST • Highlight some of the very real technical and cost-benefit challenges that have to be overcome • Make the case, that in an NGST era, with our current science interests, a groundbased 30m - 50m telescope is the necessary (if somewhat daunting) “next step”

  45. Workshop Summary (preliminary) • In view of the large number of science projects identified, there is sufficient scientific interest in building a 30-50m telescope observatory. • Moreover, there was consensus already at the end of the first day of the meeting that MAX-AT should be maximized to do science based on high resolution imaging and spectroscopy. • 10 milli-arcsecond imaging spectroscopy at 28 - 30 magnitude • This Observatory should extend and complement the capabilities of NGST and the MMA

  46. Workshop Science Cases (preliminary) • Planet formation • Formation of stars and planetary systems (disks) • Planet Formation • Imaging of planets around nearby stars • Cepheids out to redshifts z~0.1 (measure H_0) • measure W matter and H_o in far fields • Measure t_o (age of stars) • radioactive decay of Thorium in old giants below RGB tip. • Geometry of the Universe via Supernovae at z~3 (q_0) • Main goal is to break degeneracy of omega matter and omega lambda.

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