CCAT06 Holland

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Cornell-Caltech Atacama Telescope (CCAT) Rationale and science drivers Telescope Site Instruments Estimated performance Project schedule

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A timely convergence of Science, Technology, and Opportunity Many sources emit most of their energy in the FIR/submm E.g. local and high-z galaxies, star forming cores Important cooling lines for molecular clouds are in this region Why A Large Single Dish? Submm technologies are progressing First large format (> 10,000 pixel) bolometer arrays Direct and heterodyne receivers approach the fundamental limits for sensitivity

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A timely convergence of Science, Technology, and Opportunity Opportunity New submm sites have lower water vapour than Mauna Kea (e.g. Atacama, South Pole) Close proximity to ALMA would foster natural synergies A large submm telescope, delivering cutting edge science, is affordable… (fraction of cost of a space mission) Why A Large Single Dish?

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A large single-aperture telescope located on a (very) dry site Aperture: 25m Wavelength range: 0.2 – 1mm+ Field-of-view: at least 25 arcmin2 Instrumentation: wide-field imaging and spectroscopy CCAT Proposal

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CCAT Science Strengths CCAT will be substantially larger and more and more sensitive than existing submillimetre telescopes It will be the first large submillimetre telescope designed specifically for wide-field imaging It will complement ALMA CCAT will be able to map the sky at a rate hundreds of times faster than ALMA CCAT will find galaxies by the tens of thousands It will map galaxy clusters, Milky Way star-forming regions, circumstellar disks etc.

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Key Science Themes 1. How did the first stars form? - Detect hundreds of thousands of galaxies from the era of galaxy formation to provide a complete picture of this process 2. What is the nature of dark matter and dark energy? - Image hundreds of clusters to provide an understanding how they form and evolve, and to constrain crucial cosmological parameters 200μm 850μm Redshift distribution of galaxies that will be detected by CCAT at 1mJy 350μm

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Key Science Themes 3. How do stars form? - CCAT will survey molecular clouds in our Galaxy to detect the (coldest) cores (<0.1MSun) that collapse to form stars 4. How do conditions in circumstellar disks determine the nature of planetary systems and the possibilities for life? - Together with ALMA, CCAT will study disk evolution from the earliest (protoplanetary) to late (debris) stages

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Key Science Themes 5. How did the Solar System form? - CCAT will determine sizes and albedos for hundreds of KBOs, providing information to anchor models of the planetary accretion process that occurred in the early Solar System.

Committee Charter:: 

Committee Charter: Science Steering Committee Establish top-level science requirements - Determine and document major science themes Flow down science requirements to facility requirements - Telescope, instrumentation, site selection criteria, operations, etc.

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Science Steering Committee Outputs: Science document - Write-ups on major science themes using uniform format (science goals, motivation/background, techniques, CCAT requirements, uniqueness and synergies) Requirements document - Specifies requirements for aperture, image quality, pointing, tracking, scanning, chopping, etc.

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Co-Chairs - Terry Herter (Cornell) and Jonas Zmuidzinas (CIT) Leads on Science Themes - Distant Galaxies – Andrew Blain (CIT) - Sunyaev-Zeldovich Effect – Sunil Gowala (CIT) - Local galaxies – Gordon Stacey (Cornell) + Shardha Jogee (UT) - Galactic Center – Darren Dowell (JPL/CIT) - Cold Cloud Cores Survey – Paul Goldsmith (JPL) + Neal Evans (UT) - Interstellar Medium – Jonas Zmuidzinas (CIT) - Circumstellar Disks – Darren Dowell (JPL/CIT) - Kuiper Belt Objects – Jean-Luc Margot (Cornell) Ex-officio members - Riccardo Giovanelli (Cornell), Simon Radford (CIT) SSC Members

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Field-of-view (5 × 5 arcmin; goal of 20 × 20…) Major role of CCAT will be its unchallenged speed for moderate resolution surveys Strongly complementing ALMA Selected (Key) Facility Drivers Aperture (25m) Sensitivity improves as  D2 (hence time to a given S/N as D-4) Confusion limit as  D-a (where a~2 and 1.2 at 350 and 850μm respectively)

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Selected (key) Facility Drivers Chopping/scanning Modulate the signal by either chopping and/or scanning Chopping secondary mirror (e.g. 1 arcmin at ~1Hz) Scanning requires moderately large accelerations (0.2 deg/sec) for reasonable efficiency Pointing and guiding Need accurate pointing particularly for spectrographs Pointing goal is 2 arcsec rms with 0.5 arcsec offset accuracy Guiding to maintain spectro-photometric accuracy Site quality Provide significant observing time at 350/450μm

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Design: Ritchey-Chrétien/Nasmyth Focus Aperture Diameter Primary Focal Ratio System Focal Ratio Back Focal Distance Field-of-View Minimum Operating Wavelength 25 0.6 f/8 11 20 200 [m] [m] [arcmin] [m] D f1/D f/# B F-o-V min Value Units Symbol Input Design Parameters Optical Design Parameters

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Units in mm Optical Layout

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Telescope Design Design by Vertex RSI Uses approaches from radio and optical telescopes 210 panels in 7 rings, each panel about 1.7m

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Mount Design Stainless steel truss (much cheaper than CPRP…) Commercial actuators will maintain the shape

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Design by M3 in Tucson Summit facility Road and site design Oxygen enriched working areas Minimum scope to support long-term operations Telescope Facility

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Telescope Dome Concept Calotte style 50m diameter at equator 30m aperture Rib and tie structure is highly repetitive Operation via two similar rotation stages Aperture sized to keep M2 2m inside dome

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Telescope Dome Concept Shutter uses mechanical and pneumatic seals to exclude weather Interior frame rotates independently of azimuth stage

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30 km Cerro Sairecabur 5500 m Cerro Toco 5600 m Salar de Atacama Cerro Chajnantor 5600 m Cerro Chascon 5675 m ALMA, CBI, APEX 5050 m Cerro Negro 5050 m Cordon Honar 5400 m San Pedro de Atacama 2400 m NASA/GSFC

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CBI APEX Cerro Chajnantor ALMA Chajnantor Plateau (5000m)

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Site Plan: Aerial View

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Mountain Facility

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Site Plan: Aerial View

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2005 Jan 25 C. Sairecabur 5500 m 93µm PWV Submillimetre Transparency 200μm 350μm 450μm 850μm

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Instruments First light instruments proposed to be wide-field cameras (not necessarily taking in entire F-o-V but having upgrade potential) Existing spectroscopic instruments (e.g. ZEUS, Z-spec) could also be used Most likely a call for second generation instruments at some point (multi-object spectrometers, array upgrades and a possible far-IR camera?!)

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Short Wavelength Camera (SW Cam) F-o-V is ~5’ × 5’ - For Nyquist sampling at 350m this requires a 170  170 pixel array - 32,000 pixels, or 6 times that of SCUBA-2… Primary bands are: - 200, 350, 450 and 620m - Selection of bands driven by similar backgrounds and adequate sampling requirements - Filter wheel to change wavelengths First Light Instruments

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SW Cam Instrument Design

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Long Wavelength Camera (LW Cam) F-o-V from 10 × 10 (submm) to 20 × 20 arcmin (mm) - 1024 to 16,384 pixels depending on wavelength Primary bands are: - 740 and 850m, 1.1, 1.4 and 2mm - Backgrounds are lower so sensitivity requirements more of a challenge - Multifrequency operation using antenna coupled bolometer arrays First Light Instruments

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The detection process is more formally split into two steps with the LW Cam arrays How light is routed from free space to detectors Antenna coupled arrays What kind of detectors will be used? TES or MKID detectors Detector Technology

Performance Comparison: 

Performance Comparison The confusion level in this case is simply scaled by aperture area/wavelength from the (measured) SCUBA 850μm 1-σ level

Performance Comparison: 

Performance Comparison The confusion level in this case is simply scaled by aperture area/wavelength from the (measured) SCUBA 850μm 1-σ level *Compact ALMA configuration 1Slightly undersampled

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5σ, 1-hour sensitivities for various instruments CCAT Sensitivity

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5σ, 1-hour sensitivities for various instruments CCAT Sensitivity

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Confusion limit is 1 source per 30 beams and is calculated assuming CL is proportional to D-α where α=2 at 350μm and 1.2 at 850μm CCAT Sensitivity

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Dust Mass Sensitivity Dust at >30K and objects z<2 emission has a spectral index slope of ~2+β β=0 for a pure black-body, whilst β=2 for small ISM grains Taking β=1 compute the relative gain of CCAT for a given mass of dust compared with other instruments Relative to SCUBA at 850μm

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Mapping Speed Large area mapping speeds assuming the same dust mass sensitivity (relative to SCUBA 850)

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SCUBA-2 on CCAT Assumes SCUBA-2 can achieve same sensitivity per pixel as CCAT instruments

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Field Mapping Flux limit versus area mapped assuming 10sec/pointing (no overheads)

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Angular Resolution

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Number of hours/year (round the clock) available for observing at a given λ (PWV) for Sairecabur vs. the ALMA region. “CL fields” is the number of fields that can be observed to the confusion limit over a year. The “Total Time” is the sum of available hours and represents all time (day or night) with PWV < 1.1mm. Observations at some wavelengths require similar conditions, e.g. 350/450µm, so they share a common range. Note that at MK, 350/450 observations are typically done when PWV <1 mm. Time Available To Observe

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Feasibility/Concept Design Study Oct 2005 – January 2006 $2m Development of baseline concept and assessment of feasibility, initial cost estimate Engineering Concept Design June 2006 – June 2007 $2-3m Firm-up concept, key analyses, detailed and accurate cost estimate Development Phase June 2007 – June 2011 ~$94-$95m Detailed design, manufacture, integration Commissioning Phase June 2011 – June 2012 ~$1m Performance optimisation & handover to operations Project Phases and Schedule

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By 2013 there will have been a number of large-scale surveys of the submm sky (SCUBA-2, Herschel etc) Is there a clear need for a wide-field imaging capability in the submm, and does CCAT provide this? What areas can the UK contribute towards (science representation, design areas)? Outstanding Questions? At what level would we (the UK) be interested in joining the project?

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Reserve Slides

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SW Camera field-of-view The telescope delivers a 20 arcmin diameter F-o-V so why are we designing to a 5 arcmin field? Science - The initial science can be delivered with 5 arcmin F-o-V cameras Image scale - Telescope delivers a 1.2m image for a 20 arcmin field – this would be quite challenging to couple onto a background limited camera

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SW Camera field-of-view The telescope delivers a 20 arcmin diameter F-o-V so why are we designing to a 5 arcmin field? Technology - Current, and near future technology suggests 32,000 pixels is a reasonable goal for the array – this can deliver Nyquist sampled images over a 25 sq-arcmin F-o-V at 350m - A 20’ F-o-V requires 500,000 pixels at 350μm, – extremely expensive using today’s technologies - Future developments will greatly reduce the costs – therefore mega pixel cameras are postponed

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Array Technology Baseline array technology is an extension of that developed for SCUBA-2 Arrays easily deliver the requisite sensitivities (<10-16 W/√Hz) for SW Cam wavebands 4 × (32 × 40) sub-arrays to make 5120 pixels – extend to 32,000 by using 25 edge-buttable sub-arrays

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Antenna-coupled arrays Antenna-coupled arrays using a slot dipole architecture Device is broadband: can be made to cover 740μm to 2mm Bands are separated using microstrip bandpass filters Under development within the CCAT consortium at Caltech/JPL Demonstrated to work in lab 16-pixel, 4 colour array under development using microstrip filters Antenna coupled focal plane prototype device Vertical lines are slots Pie shaped structures connect to the microstrip taps that cross over the slots

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Pixel counts But pixels counts are not the only challenge: power dissipation in focal plane and number of read-out wires are just two others to mention…

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Focal Plane Geometry Focal plane geometry Processed 6-inch wafer containing ~5000 pixels