Submm Wide Field Surveys with CCATSubmm Wide Field Surveys with CCAT

Riccardo Giovanelli*

(*with thanks for material to Gordon Stacey, Jason Glenn, John Carpenter et al.)

•A 25meter FIR/submillimeter telescope that will operate at wavelengths as short as = 200 m, an atmospheric limit

• To be located in a high (5617m) desert environment

• It will take advantage one of the fastest developing detector technology of any spectral regions, opening up the last, largely untapped frontier of ground-based astronomical research

What is CCAT:What is CCAT:

Beam sizem]/100 arcsec e.g. 2” @ 200 m

FoV: 1 sq. deg.

Half WF err: 9.5 m rms

Continuum Sensitivity, 5, 1 hr : 1 mJy@ 350 m

First-light short camera: 50 kpix

Several instruments in Nasmith focus, some simultaneously accessible in large FoV

Project Cost: $120M

Who is CCAT ?Who is CCAT ?

A joint project of A joint project of Cornell University, Cornell University, the California Institute of Technologythe California Institute of Technology and the Jet Propulsion Laboratory,and the Jet Propulsion Laboratory, the University of Colorado,the University of Colorado, a Canadian academic Consortium,a Canadian academic Consortium, the Universities of Bonn & Koeln,the Universities of Bonn & Koeln, Associated Universities, Inc. Associated Universities, Inc.

Where is CCAT?

At the driest, high altitude At the driest, high altitude site you can drive a site you can drive a truck to….truck to….

CerroChajnantor (18,500 ft)

Go

og

le E

arth

Cerro Chajnantor 5612 m (18500 ft)

ALMA

Maximizing SensitivityMaximizing Sensitivity

Wish to reach confusion limit determined by Wish to reach confusion limit determined by backgrounds and aperture as soon as possible backgrounds and aperture as soon as possible maximize system sensitivity maximize system sensitivity

High site:High site: Cerro Chajnantor 600 m above ALMA site Cerro Chajnantor 600 m above ALMA site zenith zenith transparency ~ transparency ~ 1.35 times better1.35 times better

High surface accuracy:High surface accuracy: goal of 9.5 goal of 9.5 m rms m rms Ruze ~ 90% at Ruze ~ 90% at 350 350 m – contrast with APEX (18 m – contrast with APEX (18 m) m) Ruze ~ 66%: Ruze ~ 66%: 1.36 1.36

High receiver sensitivity:High receiver sensitivity: direct detection systems easily direct detection systems easily background limited with Tbackground limited with Trecrec(SSB) < 50 K – contrast with (SSB) < 50 K – contrast with ALMA with TALMA with Trecrec(DSB) ~ 180 K – (DSB) ~ 180 K – a factor of 3.3 a factor of 3.3 for Tfor Tskysky ~ 150 ~ 150 KK

High receiver bandwidth:High receiver bandwidth: direct detection systems can direct detection systems can easily take in the entire telluric windows (cameras) or easily take in the entire telluric windows (cameras) or several (spectrometers) – several (spectrometers) – 80 GHz vs 8 GHz 80 GHz vs 8 GHz for ALMAfor ALMA

Best Point Source Sensitivity:Best Point Source Sensitivity: Surprising conclusion: a Surprising conclusion: a camera on CCAT can have point source sensitivity camera on CCAT can have point source sensitivity equivalent to (25/12)^2 equivalent to (25/12)^2 1.35 1.35 1.36 1.36 3.3 x sqrt(80/8) ~ 3.3 x sqrt(80/8) ~ 80 ALMA antennas!80 ALMA antennas!

Origins of cosmic structures: We’d like to learn…

How did we get from this…

…to this?

Energy fluctuations in the very early Universe

Organization of matter into large filamentary structures

Formation of massive, dense clusters of galaxies

Hierarchical mergers of galaxies

Formation of stars and planetary systems

The First Stars, the First Galaxies

Made of Hydrogen and Helium, probably formed a few hundred Myr after the Big Bang. They must have been very massive, evolved rapidly and produced the “first batch” of elements heavier than Helium, necessary for the formation of dust, complex molecules, planets and life.

By the time the first galaxies form, the Universe is already dusty

Goods 850-5 (z=4.1) in optical (HST, Goods 850-5 (z=4.1) in optical (HST, left; Daddi et al. 2009) and submm left; Daddi et al. 2009) and submm (SMA, right) (SMA, right)

CCAT

Lagache, Puget, & Dole 2005

STARLIGHTDUST

COBE (1996)

• Dust reprocesses starlight into FIR

• Cosmic expansion shifts light of early galaxies further into submm and mm bands

The Cosmic FIR Background

Galaxy Counts and Galaxy Counts and the Cosmic FIRB at the Cosmic FIRB at Submm WavelengthsSubmm Wavelengths

HerMES HerMES Lockman Hole Lockman Hole NorthNorth

Oliver et al. Oliver et al. (2010, 2011)(2010, 2011)

• ~10% of CFIRB ~10% of CFIRB resolved directly with resolved directly with HerscheHerschell

• ~50% inferred ~50% inferred statistically, yielding statistically, yielding estimated number estimated number count models to a count models to a depth of 2 mJy/beamdepth of 2 mJy/beam

• CCAT will resolve CCAT will resolve (directly) sources to (directly) sources to 0.5-1 mJy, resolving 0.5-1 mJy, resolving the totality of the the totality of the CFIRBCFIRB

1111

P(D)

Detections

See Patanchon et al. (2010), Glenn et al. (2011)

Comparative Continuum Sensitivities, 5-sigma, 3600secConfusion limits @ 30 (dark red), 10 (cyan) beams/src

CCAT, Herschel, and ALMACCAT, Herschel, and ALMA

Approximate FOV of first-light camera

ALMA primary beam(~7)

Simulated maps of the same patch of sky based on Simulated maps of the same patch of sky based on HerschelHerschel number number countscounts

Dusty High z GalaxiesDusty High z Galaxies

Observed flux density of a dusty Observed flux density of a dusty galaxy as a function of z and galaxy as a function of z and

1mm1mm 1cm1cm100µ100µmm

10µm10µm1µm1µm

Flu

x D

ensi

ty (

mJy

)Fl

ux D

ensi

ty (

mJy

)

10c10cmm

10001000

100100

1010

11

.1.1

.01.01

SMM J2135-0102SMM J2135-0102z = 2.326z = 2.326(lensed)(lensed)

SPIRESPIRE

Ivison et al. (2010)

Blain et al. (2002)

• Wide area coverage (> 100 deg2) to overcome sample variance

• Arcsec–resolution to overcome confusion, resolve the vast majority of the CFIRB and identify source counterparts at other wavelengths

• Comprehensive submm spectroscopic follow-up to measure z and characterize galaxies’ physical conditions and composition

Desiderata for a high z SMG galaxy Survey

Atomic fine structure & molecular Atomic fine structure & molecular lines: lines:

ZEUS ZEUS

Bradford et al. (2009)Bradford et al. (2009)

Flux D

ensi

ty (

10

-18 W

/m2/b

in)

v (km/sec)

-1

0

1

2

3

4

-3000-1500 0 1500 3000

SMM J123634z = 1.2224

-1

0

1

2

-2000 0 2000

SWIRE L17z = 1.9537

-1

0

1

2

3

4

-3200 -1600 0 1600

3C368z = 1.130

-1

0

1

2

3

-2000 0 2000 4000

RXJ094144z = 1.8178

-1

0

1

2

-2000 -1000 0 1000 2000

SWIRE L25z = 1.9575

Stacey & Hailey-Dunsheath et al. (2010)

[CII] 158 [CII] 158 m, [OI] 63 & 146 µm, m, [OI] 63 & 146 µm, [NII] 122 & 205 µm, CO ladder…[NII] 122 & 205 µm, CO ladder…

Speculative: 17 Speculative: 17 m and 28 m and 28 m m lines of Hlines of H22 at high z?... at high z?...

~103 galaxies/deg2 detectable spectroscopically by CCATSpectroscopic survey of 1 in 10-100 photometric detections doable with MOS (source centroiding should be better than 1”)

• Wide area coverage (> 100 deg2) to overcome sample variance

• Arcsec–resolution to overcome confusion, resolve the vast majority of the CFIRB and identify source counterparts at other wavelengths

• Comprehensive submm spectroscopic follow-up to measure z and characterize galaxies’ physical conditions and composition

• Submm and mm observations to identify the highest z candidates.

Desiderata for a high z SMG galaxy Survey

Identifying Very High-z Galaxy CandidatesIdentifying Very High-z Galaxy Candidates

High-z galaxies will have low 350 µm to 850 µm flux High-z galaxies will have low 350 µm to 850 µm flux density ratios (“350 µm dropouts”) density ratios (“350 µm dropouts”)

flux density ratio

101

3 examples from Herschel (Dowell et al. 2010)

Bolocam Galactic Plane Survey 1.1mm @CSO (Bally et al. 2010)

BOLOCAM: OrangeVLA 20 GHz: purpleSpitzer 8 m: cyan

Structure of Molecular CloudsStructure of Molecular Clouds

Herschel 70μm, 160μm, and 350μm image at longitude = 59°

2 degrees

Molinari et al. 2010

Filaments are pervasive ...Filaments are pervasive ...

Filtered Herschel 250um image

Molinari et al. 2010

... and are where stars form... and are where stars form

Molinari et al. 2010

Filaments contains dense “clumps”Filaments contains dense “clumps”

• Clump Mass Function similar in shape to Stellar Mass Function

Is Stellar IMF imprinted in the cloud structure?

Andre et al. 2010

Aquila molecular cloud

To make a definitive determination of the clump mass function, observations require surveys:

•Sensitive to clumps capable of forming a 0.01 Msun brown dwarf – an order of magnitude more sensitive than current surveys

CCAT will probe clumps with mass ~ 0.001 Msun (25x smaller than Herschel)

Desiderata for a Molecular Clump MW Survey

To make a definitive determination of the clump mass function, observations require surveys:

•Sensitive to clumps capable of forming a 0.01 Msun brown dwarf – an order of magnitude more sensitive than current surveys

•With angular resolution < 5” to resolve 0.05 pc clumps to 1 kpc distance and to relieve the source confusion severely affecting Herschel, the BGPS, and SCUBA-2 surveys

CCAT will probe scale of ~500 AU in nearest clouds

Desiderata for a Molecular Clump MW Survey

To make a definitive determination of the clump mass function, observations require surveys:

•Sensitive to clumps capable of forming a 0.01 Msun brown dwarf – an order of magnitude more sensitive than current surveys

•With angular resolution < 5” to resolve 0.05 pc clumps to 1 kpc distance and to relieve the source confusion severely affecting Herschel, the BGPS, and SCUBA-2 surveys

•Of both the dust continuum and high spectral resolution of molecular lines – to probe the dynamics of clumps

•Covering tens of deg2 in many fields to sample different environments

•Multicolor submm observations to measure dust temperatures and masses.

Desiderata for a Molecular Clump MW Survey

A facility of large synergy with A facility of large synergy with ALMAALMA

CCAT will not match ALMA in angular resolution (beam 2”-5” will not yield morphological info); it will however match it in sensitivity and will have a Field of View 30,000 times larger FAST SURVEYOR (many objects at a time)

ALMA will deliver very high spatial resolution, but only over a very small Field of View:

Will reveal fine detail, ONE SOURCE AT A TIME

Ideal Complementarity

• October 2003: Partnership Workshop in PasadenaOctober 2003: Partnership Workshop in Pasadena

• Feb 2004: MOU signed by Caltech, JPL and CornellFeb 2004: MOU signed by Caltech, JPL and Cornell

• 2005: Project Office established2005: Project Office established

• 2006: Feasibility Study Review2006: Feasibility Study Review

• 2007-2010: Consortium consolidation, design 2007-2010: Consortium consolidation, design developmentdevelopment Site selection completedSite selection completed

• 2011-2013: Detailed Engineering Design2011-2013: Detailed Engineering Design

• 2013-2017: Construction and First Light2013-2017: Construction and First Light

“Patience, n. A minor form of despair, disguised as a virtue.” Ambrose Bierce