1. CCAT-Prime: An Ultra-widefield Submillimeter Observatory at Cerro Chajnantor
Gordon Stacey Cornell University Representing the CCAT consortium Cornell, Cologne, Bonn, Colorado, Association of Canadian Universities, AUI
04 August 2016
RMS Science Futures II

2. CCAT-Prime
Precursor for CCAT – a 25 m submm telescope on Cerro Chajnantor
Explore and develop site, reducing risk
Open up exciting new science
04 August 2016
RMS Science Futures II

3. The CCAT-p Concept Principles: Enable forefront science
Exploit CCAT partnership framework
Build on experience gained from CCAT project
04 August 2016
RMS Science Futures II

4. The CCAT-p Concept Principles: Enable forefront science
Exploit CCAT partnership framework
Established international collaboration
Established legal entity
Access to same/other funding sources for smaller project
Possibility to incorporate additional partners
Build on experience gained from CCAT project
04 August 2016
RMS Science Futures II

5. The CCAT-p Concept Principles: Enable forefront science
Exploit CCAT partnership framework
Build on experience gained from CCAT project
Understanding and analysis of infrastructure requirements, solutions, costs and risks
Body of CCAT documents: established capability
Confidence from review outcomes: demonstrated capability
Carry-over of “shovel ready” aspects
For example, archeological/geological surveys completed; no one else is ready to take off.
04 August 2016
RMS Science Futures II

6. The CCAT-p Concept
6-meter off-axis submm telescope located at CCAT site at 5600 meters on Cerro Chajnantor
Surface accuracy of <10 m (7 m goal)
High site gives routine access to 350 m, 10% best weather to 200 m, advantage at longer s
Novel off-axis crossed-Dragone design (Niemack 2016) yielding high throughput, wide field-of-view, flat focal plane immediately plus potential as Stage IV CMB observatory
Targeted science programs taking advantage of aperture size, throughput, mapping speed, superb site in “campaign-mode”
04 August 2016
RMS Science Futures II

7. Cerro Chajnantor at 5600 m
04 August 2016
CCAT-Prime

8. 5000 meter is good, but 5600 meters is better
Radford & Peterson, arXiv:
Submillimeter sensitivity is all about telluric transmission
Simon Radford has been running tipping radiometers at primary sites for more than a decade –
Simultaneous period for CCAT vs. ALMA site: median is 0.6 vs. 1 mm H2O  factor of 1.7 in sensitivity
Fraction of time
Fraction of time
04 August 2016
RMS Science Futures II

9. Median Zenith Transmission
Median CCAT transmission even better than South Pole due to warmer, less dense atmosphere
Tropics: Ω = 3 π sr, Amed = 1.1 (z < 60°)
Pole: Ω = 1 π sr, Amed = 1.4 (z < 60°)
04 August 2016
RMS Science Futures II

10. Chajnantor Site 10% Opens up the THz Windows
04 August 2016
RMS Science Futures II

11. CCAT-Prime Science
Investigating the the physical processes associated with star formation in the Milky Way, the Magellanic clouds and other nearby galaxies through submm spectroscopy and photometry
Probing of the nature of dark energy, gravity on large scales and neutrino mass sum through kinetic SZ effect
Probing the process of reionization in the early Universe through intensity mapping of the [CII] 158 m line emission associated with star formation in the epoch of reionization at redshifts from 6 to 8.
The CCAT design also well suited to a “Stage IV” CMBR observatory with ~ 10 times the mapping speed of current facilities enabling probes of inflationary gravity waves and the sum of the neutrino masses.
04 August 2016
RMS Science Futures II

12. Implementation: The Crossed Dragone Telescope Design
astro-ph/
Applied Optics 15, 1688
04 August 2016
RMS Science Futures II

13. Optical Design Niemack, 2016 astro-ph/1511.04506
Applied Optics 15, 1688
Twin large convex mirrors deliver an f/3 beam with a flat focal plane
Field of view is very large ~ 7 at 150 GHz for 6 m aperture
Flat focal plane
Two 6-m aperture telescope designed with f=3 (top and bottom) tilted to 45 elevation. Both have flat tertiary mirrors; optical clearances can be adjusted by changing telescope parameters and fold angles.
04 August 2016
RMS Science Futures II

14. Fails the “spill-over on sky” test And will need a ground shield
Clear Problems:
Fails the “spill-over on sky” test
And will need a ground shield
04 August 2016
RMS Science Futures II

15. The CCAT Pathfinder Concept CCAT-prime: CCAT-p
04 August 2016
RMS Science Futures II

16. In the range of 105 to 106 pixels to fill focal plane
300 GHz
230 GHz
150 GHz
300 GHz
Plate scale is 32 cm/degree 
Break it into subcameras with ~ 28 cm dewar windows
Lenses are thinner – less lossy
Structural support is much easier
Camera “tubes” enable incremental build up to final arrays
50 optical tubes in inner regions providing diffraction limited performance at 150 GHz; additional 22 in 100 GHz diffraction limited zone
In the range of 105 to 106 pixels to fill focal plane
04 August 2016
RMS Science Futures II

17. Tubes and Lyot Stops
04 August 2016
RMS Science Futures II

18. Science Cases
04 August 2016
RMS Science Futures II

19. Surveys of the Milky Way
15” imaging over degree scales of the Milky Way, LMC, etc in:
[CI] tracing gas temperature and mass
CO tracing gas excitation, shocks, density and mass
[NII] tracing embedded SF regions and numbers of ionizing photons
Tracing accumulation and flows of gas into cores and young stars
Requires high site for submm transmission
04 August 2016
RMS Science Futures II

20. Fundamental Physics with kinetic Sunyaev-Zel’dovic Effect
04 August 2016
RMS Science Futures II

21. SZE: Sunyaev-Zel’dovich Effect
Spectral distortions of CMB spectrum:
tSZ: due to random thermal motions of scattering electrons
rSZ: due to populations of relativistic electrons
kSZ: due to bulk velocity of the cluster relative to the CMB rest frame
04 August 2016
RMS Science Futures II

22. The CCAT-p Concept kSZ: Kinetic Sunyaev-Zel’dovich Effect
submm galaxies
tSZ: dashed red
rSZ: dashed orange
kSZ: dashed blue
Challenging to separate various signals on CMB: tSZ, rSZ, submm galaxies and radio sources leaving kSZ
Observations over a wide wavelength range: 3.3 mm to 350 m needed
Need better sensitivity and resolution than Planck
radio sources
kSZ
Simultaneous bands
350 m – 3 mm
Mike Zemcov
04 August 2016
RMS Science Futures II

23. Constraints on Peculiar Velocities with kSZ effect
A survey of 3000 hours, over ~1000 sqd with CCAT-p will substantially improve on upcoming CMB surveys.
“no gal noise”: sub-mm emission from faint galaxies perfectly subtracted
On going analysis by M. Niemack and
F. deBernardis
Optical depth of intracluster medium and peculiar velocity
04 August 2016
RMS Science Futures II

24. Constrains on Dark Energy and Modified Gravity with kSZ
Forecast dark energy and modified gravity constraints based on measuring 1000 clusters with 100 km/s accuracy (red); SPT-3G projections shown in blue.
Such uncertainties will also enable a measurement of the sum of neutrino masses with a 1 uncertainty of ~ 0.03 eV.
Blue: SPT3D expectations 4000 clusters: red what you could do with 1000 clusters with better
04 August 2016
RMS Science Futures II

25. Intensity Mapping of [CII] in the Epoch of Reionization
Detect aggregate clustering signal of faint galaxies in the EOR via redshifted [CII] 158 m line
Spectral line IM gives 3-D spatial information
- Process of structure formation
- Fluctuations trace DM density fluctuations
SKA 21 cm HI line (HERA)
Requires SKA collecting area
Foreground contamination/RFI
04 August 2016
RMS Science Futures II

26. A Familiar Example of Intensity Mapping
Spectral line intensity mapping:
Not just fluctuation spectrum but how it changes over EOR redshift interval
04 August 2016
RMS Science Futures II

27. Intensity Mapping of [CII] from the EOR
Detect aggregate clustering signal of faint galaxies in the EOR via redshifted [CII] 158 m line
[CII] directly traces sources of reionization (SF galaxies)
Recent ALMA detection of [CII] in “normal” galaxies at z = 5-6 (e.g. Riechers+ 2014)
Enhanced [CII] to dust continuum compared to lower redshifts  strong signal
04 August 2016
RMS Science Futures II

28. Full power in combination with HI 21cm experiments
HI 21cm: traces neutral gas not yet re-ionized
[CII] 158m: traces ionization sources (star forming galaxies)
[CII] advantage:
No radio frequency interference
Can be done before full SKA built
04 August 2016
RMS Science Futures II

29. Intensity Mapping of [CII] from the EOR
Measure large scale spatial fluctuations of collective aggregate of faint galaxies via redshifted [CII] 158 m line (+possibly other lines at other z’s)
Resolution into individual galaxies not required
Clustering scale 0.5 to 1 Mpc or ~1-2’ at z = 5-9, - good match for 6-m aperture 1mm)
162 surveys: spectral/spatial mapping speed critical
FoV ~ > 1 matches 40 Mpc void size-scale: systematics
Need moderate spectral resolution R ~
Bandwidth of z ~ 5-9 signal is mm ( GHz)
Identify interloper lower z CO by line multiplicity – complete at z > 0.8
Sensitivity is at a premium: high site is helpful
04 August 2016
RMS Science Futures II

30. Redshift of Interlooper
CO Interloopers
CO Transition
Redshift of Interlooper
[CII] Redshift
(Distance Ratio)2
CO/[CII] Flux Ratio
(2-1)
41,000-11,000
65-18
(3-2)
41,
20-2
(4-3)
940-98
5-0.5
(5-4)
240-41
1-0.2
0.80
Naive first order calculation of effects of low redshift interloopers
Used standard line ratios, and assumed same luminosity sources at low and high redshifts
Lowest redshifts are known sources
Redshifts ~0.1 to 0.8 may be problematic – depends on details
Redshifts beyond ~ 0.8 no problem since 2 CO lines will appear
04 August 2016
RMS Science Futures II

31. Future Stage IV CMB Observatory
Next generation CMB mapping
Probe inflationary gravity waves at tensor-to-scalar ratios as low as 0.001
High-significance measurement of neutrino mass sum
High-throughput, wide-field, flat focal plane design at high site even on 6 m telescope would enable mapping CMB 10X faster than ACTPol or SPT-3G
CCAT-p would offer existing platform for deployment of cameras with > 105 detectors, likely developed with DOE funding on 5+ year timescale.
Synergistic with Simons Observatory
Adds the high frequency component that may be critical for removing submm galaxy foregrounds
04 August 2016
RMS Science Futures II

32. Instrumentation Science requires at least three instruments
Star formation in local galaxies requires large format heterodyne spectrometer arrays
kSZ requires 350 m – 3.3 mm multichroic camera with degree-size field of view
This camera might be precursor to larger FoV CMBR camera
EOR studies requires large BW  FoV ~ 20,000 pixel direct detection spectrometer
04 August 2016
RMS Science Futures II

33. U Cologne: CHAI Heterodyne, dual frequency array
500 GHz (600 μm) and 850 GHz (350 μm): CO(4-3), CO(7-6) [CI]  2
64 (baseline), 128 (goal) pixels in each band
04 August 2016
RMS Science Futures II

34. Example First Light Camera
Seven subcamera “tubes” populated with ~1.5 f pixels with multichroic TES bolometers
FoV ~ 1 degree each  60,000 pixels at 350 m; 6000 at 1.1 mm
Cameras are modular (size, optics, filtration), easily exchanged
Start with very modest numbers of pixels and growth to fill out camera, then entire CCAT-Prime FoV if so desired
Note pupil for cold stop,
04 August 2016
RMS Science Futures II

35. Large BW  FoV Spectrometer
Trans-mm wave from ~ 0.95 to 1.6 mm ( GHz)
Direct detection for optical sensitivity
Resolving power requirement is modest, ~ 500 or 600 km/sec
Need a spectral  spatial product > 20,000 to complete a 162 survey in 4000 hours.
CO foregrounds: BW = 127 GHz. At z = 0 10% of the time get two lines. At z > 0.8 get two lines always.
04 August 2016
RMS Science Futures II

36. Spectrometer on a Chip
Essentially filter bank tapping off of a superconducting transmission line
Each channel is a half-wave resonator that dumps power to the detector
Can cover very large instantaneous bandwidths, so that source redshifts (and science) are obtained
312 spectral  64 spatial pixels
Early in development, but promising
Several techniques for generating a broad bandwidth direct detection spectrometer.
Several groups working in this field including
Delft: DESHIMA GHz, 6-9 pixels, R ~ 1000 (A. Endo)
GSFC: MicroSpect: S.H. Moseley
JPL: SuperSpec GHz, R ~ 400 to 700 (C.M. Bradford)
04 August 2016
RMS Science Futures II

37. Or…
Might well be an “evolution” from first light spectrometer to more sophisticated technologies
“Traditional” grating spectrometer with full BW and “long slit”
Imaging FPI spectrometer that spatially multiplexes with large FoV cameras
04 August 2016
RMS Science Futures II

38. Status New concept developed in early spring of this year
Approved for further study
Need additional partner(s) at the level of $5 M
Hoped for start is within a year
04 August 2016
RMS Science Futures II