Maximum Aperture Telescope Workshop Organized by AURA Chaired by Jay Gallagher MAX-AT Workshop Madison, Wisconsin, August

Basic Ideas for Very Large Aperture Telescopes the case for continuing groundbased astronomy Matt Mountain Gemini Telescopes August 1998 MAX-AT Workshop Madison, Wisconsin, August

Basic Ideas for Very Large Aperture Telescopes the 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 21 st 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 u 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”

What is the case for a new groundbased facility? ORM LBT 2 MMT Subaru Gemini S Palomar WHTUKIRTCFHTWIYNARCTNGMPAKPNONTTCTIOAATESOIRTF VLT 1 VLT 2 VLT 3 VLT 4 Keck 1Keck 2 HET Magellan 1 Magellan 2 LBT 1 Gemini N ? Science “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

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

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) Adapted from Science, vol. 274, pg. 912 l Dynamics, abundances’ requires - spectral resolutions > 5,000 l Isolating individual objects or phenomena requires - high spatial resolution l Imaging spectroscopy at high spectral and spatial resolution requires - collecting area

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

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

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

“Deconstructing the M16 Pillars with Gemini” Approximate field of view of Gemini Mid Infrared Imager Embedded forming stars 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”

Going beyond Gemini Jupiter Solar 10 pc 500 mas Gilmozzi et al (1998) Log 10 F  (  Jansky)  m) 10  t = 10,000s R = 1800 Gemini x 30 Models for 1 M J Planets at 10 pc from Burrows et al 1997

How we will be competitive from the ground The “ Next Generation ” Space Telescope (NGST) will probably launch  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

Sensitivity gains for a 21 st Century telescope For background or sky noise limited spectroscopy: S  Equivalent Telescope Diameter.   N Effective Aperture Width   For background or sky noise limited observations: S  (Effective Collecting Area) 1/2.   N Delivered Image Diameter    To meet these scientific challenges: S/N  30 x S/N of a 8m ~ 10 m Telescope S/N x (10 6 ) 1/2

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

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

Relative Signal to Noise (SNR) of NGST/Gemini -- assuming a detected S/N of 10 for NGST on a point source, with 4000s integration 22 Spectroscopy between the OH lines

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 magnitudes

“its resolution stupid..” Gemini 8-M 8 2 x 50 CHARA Keck 1 & VLTI Facility Baseline Collecting Area (m) (m 2 )

“its resolution stupid..” Gemini 8-M 8 2 x 50 CHARA Keck 1 & VLTI VLIA ~ (16 x 8m) Goal: arcsecond images at 2.2 microns signal/noise gains ~ 10 compared to 8m telescopes sensitivity gains ~ 10 2 over Gemini for point like sources Facility Baseline Collecting Area (m) (m 2 )

“its collecting area stupid..” Gemini 8-M 8 2 x 50 CHARA Keck 1 & VLTI Facility Baseline Collecting Area (m) (m 2 )

“its collecting area stupid..” Gemini 8-M 8 2 x 50 CHARA Keck 1 & VLTI m M Telescope Goal: 0.01 arcsecond images at 2.2 microns signal/noise gains ~ 30 compared to an 8m sensitivity gains ~ 10 3 over Gemini for point like sources Facility Baseline Collecting Area (m) (m 2 )

Modeled characteristics of 20m and 50m telescope Assumed detector characteristics  m <  m 5.5  m <  m I d N r q e I d N r q e 0.02 e/s 4e 80% 10 e/s 30e 40% Assumed point source size (mas) 20M 1.2  m 1.6  m 2.2  m 3.8  m 4.9  m 12  m 20  m (mas) M 1.2  m 1.6  m 2.2  m 3.8  m 4.9  m 12  m 20  m (mas) 

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 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 Groundbased advantage NGST advantage

“its sensitivity and resolution..” Gemini 8-M 8 2 x 50 CHARA Keck 1 & VLTI m M Telescope Goal: 0.01 arcsecond images at 2.2 microns signal/noise gains ~ over Gemini sensitivity gains ~ 10 3 over Gemini for point like sources Facility Baseline Collecting Area (m) (m 2 )

50m Point Source Sensitivities 10  10,000s

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

AO performance on a 50m Telescope Chun, 1998

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

The Challenge - Multiple Laser Beacons * * * * ** SR FA ~ 0.75 requires N Beacons 1.2  m  m  m  m  m  m<=  m<=1 - still a lot of technologies to develop

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

Imaging of the Universe at High Redshift with 10 milli-arcsecond resolution Simulated NGST K band image Blue for z = Green for z = Red for z =  = arcseconds Isoplanatic patch at 2.2 microns for 10mas imaging 8K x 8K array (3mas pixels)

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

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

Spectroscopic Imaging at 10 milli- arcsecond resolution Simulated NGST K band image Blue for z = Green for z = Red for z =  = arcseconds 2K x 2K IFU 0.005” pixels - using NGST as “finder scope”

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

50 Meter Telescope Concept 50 m 2m diameter adaptive secondary producing collimated beam, with 1 arcmin. FOV

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

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…..

“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 $40M Total $1,086M ) 50m Telescope costs (1997$) Scaled costs Constrained costs  Keck + Gemini + ESO-VLT + Subaru) = $1,560M

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

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

Basic Ideas for Very Large Aperture Telescopes the 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 21 st 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 u 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”

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 magnitude This Observatory should extend and complement the capabilities of NGST and the MMA

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  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.