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The Atacama 25-m Submillimeter

Telescope Project

Terry Herter (Cornell)

R. Brown, R. Giovanelli, G. Stacey (Cornell)

J Zmuidzinas, D. Woody, S. Golwala, A. Blain (Caltech)

for the Cornell-Caltech Team

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The Atacama 25 m Telescope Project

Cornell and Caltech recently signed an agreement to participate in a study for developing a 25 m class submillimeter telescope. Very likely located in high Atacama desert in N. Chile

This facility is to be completed in about 2012.

Since the AT 25 is a relatively late player in this field – it is critical that it cover sufficient new phase space to pursue compelling new science.

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SpitzerSpitzer

HerschelHerschel

APEXAPEX

ALMAALMA

JCMTJCMT

LMTLMTATAT

Sensitivity Comparisons

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The Atacama 25 m Telescope Project

Aperture: 25 meter class is significantly larger than APEX, SMT, CSO or JCMT – ensures that it is not confusion limited in exposures of 24 hours or less.

Water Vapor Burden: Need consistently lower burden than 1 mm to reach the short submm windows

Surface Accuracy: Desire high surface accuracy (~ 12 um rms) to obtain good efficiency in the 200 um window (1.5 THz)

Field of View: Faint source surveys a forte – therefore requires large FOV > 5’ which could be populated with 10,000 element arrays.

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Study Phase

Study phase will look into science/technical trades 1.5 – 2.0 year duration

Some particular trades/study areas: Shortest : 200 m vs. 350 m

Science, site, surface accuracy Closed vs. Open loop figure control Aperture Dome design

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Working Groups for Study Phase

Group Topic Group Chair

S1 Solar System Don Campbell

S2 Star Formation Paul Goldsmith

S3 Galaxies Andrew Blain

S4 Cosmology Sunil Golwala

T1 Telescope Jonas Zmuidzinas

T2 Instrumentation Gordon Stacey

T3 Site Riccardo Giovanelli

T4 Management T. Phillips/ W. Langer

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1mm 350 m 200 m450 m

best Chile and South Polebest Chile and South Poleaverage Chile and South Pole

Hawaii

The Sites: A Water Vapor Issue

It is clear that Chilean and Antarctic Sites are very exciting

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The Site: Peaks Near the Chajnantor Plain

Key Question:Does the inversion layer descend below nearby peaks?

Case I:

Case II:

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The Site: The Inversion Layer

The Key Answer: Yes, it appears that it does!

Ongoing site survey to verify the gains.

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The Site: Which Peak?

High sites include Chascon and Honar A more accessible site is Negro – may have

equivalent water vapor burden

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View from Cerro Negro

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Science Goals Galaxy Formation and Evolution ISM, Disks, Star and Planet Forming Regions CMB and the SZE Solar System Studies

KBOs and Irregular Satellites

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Starburst systems emit the vast majority of their light in the far-IR

Starburst Systems

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For star forming galaxies, the far-IR luminosity is proportional to the star formation rate. The AT will detectSFR~10-30 M/yr for z < 3, and SFR~40 - 100 at z ~ 10!

AT 25 m 5 , 10,000 sec

SIRTF, LMT(1100) confusion limited

Star Formation Sensitivity

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10

100

1000

0 2 4 6 8 10Redshift

SF

R (

M_s

un/y

r/be

am)

SIRTF(70)AT(200)AT(350)AT(450)AT(620)AT(740)AT(870)LMT(1100)

AT: 25-m, SNR = 5, t = 10000 sec

SIRTF, LMT, AT(870): confusion ltd.

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A 3000 hr survey with the AT might detect ~ 500,000 galaxies,A 3000 hr survey with the AT might detect ~ 500,000 galaxies,mostly with z ~ 2 - 4, but easily up to z ~ 10 (if they exist)mostly with z ~ 2 - 4, but easily up to z ~ 10 (if they exist)

Submm Photometric Redshifts

Access to multiple FIR bands can yield photometric redshifts accurate enough (~ 20%) to allow investigation:

Star formation history of the Universe

Evolution of large scale structure

Herschel SPIRE simulation

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AT 25 m Primeval Galaxy Survey The AT brings a unique combination of properties:

statistical wealth (number of detections) access to multiple submm bands (photometric z) quality of SED determination redshift and star formation rate stretch access to fine structure FIR lines ability to carry out deep surveys

These ensure that the AT 25 m telescope will be a prime instrument for study of galaxy formation

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AT 25 m Instrumentation Bolometer Array Cameras – more than 10,000 pixels

350 and 450 m at first light 620 and 850 m, likely in same dewar – filter wheel? 200 m likely 3rd band

Direct Detection Spectrometers R =1000, 4 x 256 short slit grating spectrometer R = 100, Z-Spec like wave-mode coupled spectrometer

Coherent spectrometers for high spectral resolution science: e.g. Galactic star formation studies

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Conclusions

Several powerful new facilities coming on line or planned

These facilities are planned for the best sites to take advantage of the short submillimeter windows

Development of large format bolometer arrays key to success

Sites, apertures, and bolometer arrays enable these facilities as “finders” for the ALMA array