Star Formation History and the Large-Scale Structure of the ...

Science with the Atacama

Large Aperture Telescope







1

The Atacama Niche: Mid to Far-IR

 Large aperture (> 15 m)

 High spatial resolution

 Relatively easy to get diffraction limited in the mid-IR

– Seeing ~ -1/5 if 0.5 m = 0.35” then 15 m LAT becomes

diffraction limited at 13 m (13 m = 0.18”)

 /D ~ 0.010 to 0.014”  (m) for 15 to 20 m aperture

 Sensitivity

 Site with low water vapor

 Enables access to normally blocked windows in

mid- and far-infrared

 30-45, 250, and 350 m windows

 Enables unique science



2

1

200 um H2O

800 um H2O

0.8

Observing Bands

Telluric

Transmission









0.6

Transmission

0.4

N Q

0.2





0

10 15 20 25 30 35 40 45 50

Wavelength (um)



1





0.8

Transmission









0.6





0.4

30° from zenith

0.2





0

100 150 200 250 300 350 400 450 500 550 600

Wavelength (um) 3

Large Atacama Telescope (LAT)

Science Drivers

 Formation of planetary systems:

 Mid-IR imaging and spectroscopy of circumstellar and

protoplanetary disks at the scales of 10‟s of AU.

 Star formation:

 Global unbiased sub-mm searches for protostellar objects

 Far-infrared (200 mm) imaging of young, embedded clusters

(energy peaks here) – highest spatial resolution at these ‟s

 High resolution mid-IR spectroscopy to diagnose physical,

dynamical and chemical conditions around forming stars.

 The AGN – starburst – black hole connection:

 Explore the link between AGN‟s, starbursts, ULIG galaxies,

and supermassive black holes through mid-IR imaging and

spectroscopy.

 LSS and SF History:

 Explore the large scale structure and the star formation history

of the Universe through near IR and FIR/sub-mm surveys. 4

Formation of Planetary Systems

What is the process from PS disk 

Protostar + Disk  Debris Disk 

Planetary System?

 How and when do planets start forming?

 Fragmentation or agglomeration?

 Simultaneously with central star or later?



 What are the chemical and physical properties

of proto-planetary material?

 How do they change with time/radial distance?

Credit: Paul Harvey (Texas)

Luke Keller (Cornell)



5

Pre-Main-Sequence Disks: I

 Late stage pre main

sequence disks are

known from visible

work.

 However, with the LAT

we could peer through

the cloud at the disk

and detect its emission.

 Very few examples of

earlier stages, e.g.

Herbig Ae Star MWC

480: transition from

proto-stellar disk to

debris disk?

6

Pre-Main-Sequence Disks: II

 Closest star formation sites are ~ 150

pc distant (e.g. Ophiuchus cloud)

 Continuum sensitivity

 Can detect a few x 10-4 Lsun at 150 pc (10

 in1 hour)

 Spatial Resolution ~ /70 (“) (15 m)

 16-85 AU at 8 to 42 m at 150 pc

  Can detect and resolve disk

structure, chemical gradients,

dynamical effects of proto-planets,...

 Wavelength Coverage to submm

 Wide range of radii ( temperature)

observable at high sensitivity/resolution Rho Ophiuchus

 Dust parameters (T, emissivity, etc)

constrained.

7

Pre-Main-Sequence Disks: III

Mid-infrared Velocity

Resolved (R ~ 105)

Spectroscopy:



Dynamics/Chemistry of Disks

 Accretion parameters from

velocity resolved [SIII],

[FeIII] lines

 Dynamics and morphology

from H2 lines.

 Top: gap formation due to

young planet (GSMT report

– Geoff Bryden)

 Bottom: simulate H2 profile

of a continuous disk vs. disk

with a gap (Lacy)

8

Later stages: Circumstellar Debris

Disks

 IRAS: the “Vega” phenomenon (Aumann et al. 1984)

 Main sequence stars with far-IR excesses

 emission from dusty circumstellar (debris) disks.

 ~ 20 to 50% of of nearby stars have such debris disks

 Emission typically peaks at  > 30 m.

 Debris disks properties can be used to characterize

stellar/planetary systems:

 Dust lifetimes are much smaller than stellar age implying that the

dust is continually being created – ground up asteroids, comets?

 Asymmetries in dust distribution can reflect perturbations by

planetary bodies

 LAT can easily resolve the nearby disks and obtain dust

SEDs  dust properties: temperature, composition

(spectrophotometry) size and mass.

9

Circumstellar Debris Disks: II

Left: mm map of Vega

Vega disk (Wilner et

al.)



Right: Model fitting

of mm wave

observations: M 1)

 no PAH features

5 10 20 17

30 40

 strong mid-IR continuum.

Wavelength (m)

An often overlooked benefit of

high spatial resolution…

 Line ratios between ionization states in the mid-IR are a

great diagnostic, but the scientific results were a bit

disappointing with ISO. Why?

 The ISO beam was large: ~ 22”  8 kpc at Arp 220.

 The beam encloses much of the star forming disk.

  Line and continuum emission from star formation regions can

swamp AGN emission.

 SIRTF, with its 10” beam may well have similar issues

 The very small Atacama beam (0.1 to 0.5”) is much

better: ~ 40 to 200 pc at Arp 220.

 Brings the wheat out of the chafe (or raisins out of the

bran)!

Can resolve AGN from surrounding star forming

regions! 18

Core of Radio Galaxy NGC 4261









LAT Beam:

~ 25 pc









19

Star Formation History of the Universe

 Optical surveys indicate that the mean SFR in the Universe was

much greater at z ~ 1  3 (e.g. Madau et al. 1996)

 COBE revealed a cosmic far-IR background with energy > the

integrated UV/optical light  dust extinction is important in the early

Universe!

 About the same time, the

first SCUBA and ISO

surveys were released

indicating even greater

rates of star formation.

 To accurately determine

the SFR requires both

optical and far-IR/submm

surveys. Blain et al. 2002



20

Star Formation History of the Universe

 Goals:

 Map the Large-Scale Structure of the Universe at 2 to 8 Gyr after

the Big Bang (3 > z > 0.4)

 Map the SFR history over the epoch of galaxy assembly

 Method:

 Simultaneous Near-IR and sub-mm surveys

 Measure the redshifted H luminosity in the near-IR bands, and the

FIR emission in the submillimeter windows.

 ~100 nights/year for ~3 years

 Products:

 Photometry –Synergy with SIRTF surveys (SWIRE)

 spectra (SED, z, EW(H), LFIR, [CII]) of more than 4 million

galaxies



21

Redshift Surveys and Large Scale

Structure

 The evolution of LSS and of the power spectrum of

density fluctuations requires deep z-surveys



 At high z, large co-moving volumes are generally

very sparsely sampled



 This is compounded by the fact that the density

contrast diminishes as z increases



 Thus any observational realization of LSS at high z

requires very rich z surveys

22

Optical Diagnostic Emission Lines

Line AGN SB Sc z(J) z(H) z(K)

OII 0.25 1 0.15 1.4-2.5 3.0-3.8 4.3-5.7

3727

Hb 0.15 0.3 0.3 0.8-1.7 2.1-2.7 3.1-4.1





OIII 1 4 1 0.8-1.7 2.0-2.6 3.0-4.0

5007

H 1 1 1 0.4-1.0 1.3-1.8 2.0-2.8





CIV 12 4.8-7.0

1549









23

Near IR Instrument and Sensitivities

 4096 x 4096 pixel array

 Covers J, H, K bands sequentially

 1000 slits, R = 2000 grisms inserted into the beams

 Assume 0.5” seeing, and 0.25” pixels  17.1‟ FOV

Band Redshift Fmin L(H)min L(G)min N Scale texp

-2 -1

erg cm s Watts L (arcmin)-2 kpc/” seconds

(5)

J 0.4 – 1.0 1.4E-16 1.2E34 3E9 20 6.6 1000

H 1.3 – 1.8 1.4E-16 1.8E35 5E10 2 7.9 2000

K 2.0 - 2.8 0.7E-16 2.5E35 6E10 2 7.6 4000



Assumes the Gallego et al. (1995) H LF for the local Universe, and

LF as suggested by Hopkins et al. (2000) for z=1.3



J band -- 6 x 1000 seconds

H band -- 2000 seconds 12.3 pointings per square degree

K band -- 4000 seconds

requires 100 -- 8 hour nights per year to cover 20 sq. degrees

24

Detection Rate

(Assuming “normal galaxy” Line Strengths)



Band n(Halpha) [dz] n(OIII) [dz] n(OII) [dz]

____________________________________________________

J 1.4  106 [0.4 - 1.0] 4.4  104 [0.8 -1.7] 2000 [1.4-2.5]

H 1.4  105 [1.3 - 1.8] 600 [2.0 - 2.7]

K 1.4  105 [2.0 - 2.8]





 Assuming a 50% detection rate…this yields 860,000

detections per year!

 A 5 year survey will yield 4.25 million galaxies at

redshifts up to z = 2.8, plus a large number of AGN‟s

at z between 3 and 5 (via OII and OIII)



25

Submillimeter Surveys: SCUBA Sources

One can detect a million

SCUBA sources at high z

1014

 SCUBA sources  ULIG

Arp 220: z =0.018 galaxies, such as Arp 220

1013  99% of its energy comes out in

the far-IR - submm bands

 At high z, the 60 um bump is

1012 redshifted into the submillimeter

LAT submillimeter

F [Jy-Hz]









bands -- the “negative K

bands and 5 

correction”

sensitivities

 Flux stays constant with z at

1011





300 um to 1 mm!

1010

 Directly samples the

luminosity function for star

109 forming galaxies

Arp 220: z = 2

 200 m band critical for sampling

SED, hence z, L

108

 Best wavelengths to look for

Arp 220: z = 3 “protogalaxies” in the early

107 Universe!

1000 100 10 1 26

Wavelength (m)

Submm Surveys: “Normal Galaxies”



 It can be shown using the work of Condon (1992), that

the far-IR luminosity of star forming galaxies is roughly

given by 100 times the H luminosity:

LFIR ~ 100 LH

 In 1 hour, a bolometer array camera in the submm on

the LAT can detect (5) the redshifted far-IR emission

from starforming galaxies at the same flux levels (the

same galaxies) as our H survey!

z = 0.7 LFIR = 4  109 L ~ 140 L (H)

z = 1.5 LFIR = 3  1010 L ~ 70 L (H)

z = 2.4 LFIR = 1  1011 L ~ 105 L (H)

 Great match! The two surveys can be performed

simultaneously, with bolometer camera off-axis.

27

Atacama Bolometer Array Camera

 64  64 pixel arrays of TES bolometers

 Bands at 200, 350, 450, 740 and 870 m

 Critically sampled at 350 m, beam ~ 5”  2.7‟  2.7‟

FOV

 Bands at 200, 350 and 450 m, enable photometric

redshifts: spectroscopic follow-up with [CII] line

 Based on SCUBA source counts, with 20 second

exposures per field, expect to detect ~ 1800 sources

in 1 hour of integration time

 This is a bit different strategy than the detection of star

forming galaxies --- this large area mapping will detect

more of the most luminous, rare sources

 For a dedicated 600 hour survey, we expect to detect

~ a million distant galaxies in a 270 (°)2 field.

28

What’s special about this survey ?

 Order of magnitude larger than anything planned - will

provide unprecedented view of high z LSS

 Deep I and II on Keck: ~ 50,000 redshifts

 e.g. VIRMOS on the VLT: ~ 150,000 redshifts More...



 Unprecedented survey depth (z ~ 3), allowing effective

investigation of galaxy formation history over

significant epochal range

 Keck and VLT surveys: 0.5 105  R 5

 [NII] to z ~ 3

 [OI] in ULIGs to z ~ 6

 [OIII] in ULIGs to z ~ 6

 With the proper spectrometer these lines could be

used as a redshift indicator: Uniquely bright

 Probes the physical properties of ISM exposed to UV

starlight  the current day stellar mass



Probes star formation in the epoch of

galaxy formation

35

Summary

 Unique niche offered by a large telescope at the

Atacama site

 Relatively unexplored windows

 Highest spatial resolution in many of these windows

 Very high sensitivity

 Science topics:

 Star formation

 Extra-solar planetary system studies

 The ULIRG/Starburst/AGN connection

 Distant galaxies

 Large Scale Structure

 Galaxy formation

 Your topic here:

 Population III

 Dark energy

 Solar system studies

… 36

LAT 20 m Continuum Point Source Sensitivity

Atacama Telescope Sensitivity Comparison

1000

20-m, 0.25 optical seeing

20-m, Perfect AO

100

HST

Keck

10 SIRTF Spectrograph

NGST

Jupiter at 10.0 pc

1

F_nu (mJy)









0.1



0.01



0.001



0.0001



0.00001



0.000001

1 10 100 1000

Wavelength (um)

5 in 10,000 sec, assumes no

OH suppression in near-IR. 37

38

Near-IR

Backgrounds









Credit: Gillett

and Mountain



39

Galaxy Evolution

 Galaxy number counts vs. z to z = 5-6, and to

luminosities 6) more

 Missing items:

 Photometric redshift surveys,  > 2.2 m science, galaxy

morphology at NIR diffraction limit, synergies with other

facilities (ALMA, SKA).





40

LSS and Cosmology



 3D baryon map z ~ 3: more

 Galaxy z-survey and IGM tomography

 The emergence of LSS more

 Studies of proto-clusters

 Evolutionary cosmology more

 Change in the equation of state



 Basic Requirements more

 Wide-field light bucket with moderate AO

 With 30-m look to 10x fainter => 100x more sources

 10-20‟ FoV, R ~ 500 spectrograph, 0.3” seeing



41

Near Infrared Redshift Coverage









42

Submillimeter Surveys

SCUBA-2 on JCMT

 30,000 pixels camera

 7 times larger than our baseline.

 However, the technology development is linked, so that we

expect similar sized arrays.

 ~ 5000 sources in 250 hours

 LAT 100 times this number in similar time due to

jump in sensitivity

 the optical quality of the LAT telescope

 quality of Atacama site

 20 times more sensitive at 350





43

Comparisons with far-IR Surveys



 SIRTF/MIPS -- very high sensitivity, but relatively

large beams: 45” @ 160 m, and 20” @ 70 m 

rapidly ( 25 hours per

field!

 Herschel/SPIRE

 24” beam at 350 m  rapidly confusion limited

 Sensitivity is not as good as the LAT

 But, Hershel surveys can cover very large areas,

 and FTS obtains redshifts in the range from 0.2 to 1.5.

44

Survey Strategy & Synergy with

SIRTF-1

 Follow SIRTF fields: closest in sensitivity

 Combine data for SEDs: Photometric redshifts,

luminosities

 LAT has better positional accuracy, and is not

confused  follow-up spectroscopy

 Since it is confusion limited at 160 m, SIRTF will

detect many more galaxies with its high sky coverage

 These surveys will detect many more of the true

beasts

How common are these “protogalaxies” in the early

Universe? 45

Survey Strategy & Synergy with

SIRTF-2

 Atacama 15 m is “deep” surveyor - detecting

relatively few sources, but going to fainter galaxies

and resolving more of the far-IR/submm background.

 How fast, and in what way (luminosity or density) are

starburst galaxies evolving in the early Universe

 -- Addresses questions of top down, or bottom up

galaxy formation

 Survey can go on continuously! Need not

interfere with other observations Return...





46

Sensitivity of the LAT at 350 m

Telescope Aperture fss MB Effective sky T(rec. + Sensitivity

Area (m2) bknd) Line Contin

-uum

JCMT 15 m 0.65 0.3 34 0.25 320 94 24



ALMA 6412 m 0.65 0.8 3762 0.30 450 1 1

Atacama-15 m 15 m 0.95 0.8 134 0.65 150 4 1





 Surprisingly enough, the “perfect” surface, and very low H2O 

Atacama 15 m telescope is competitive with ALMA for 350 m

point source detection in spectral lines!

 For continuum observations, 15 m direct detection (bolometers)

are equal for point sources!

 Bolometer arrays  1000‟s of times advantage for broad field

mapping

 Atacama 15 m finds sources for detailed study by ALMA array



47

Explorations of Distant Galaxies

Arp 220: z =0.018 • Atacama 15 m is the best

1014

facility from 200 to 450 m for

detecting the far-IR continuum of

starburst galaxies at z ~ 2 to 6

1013

It is only beaten per beam by

ALMA at 850 m, and SIRTF in

1012

IRAS 60 m the near-IR

F [Jy-Hz]









1011

ISOPHOT

• Combination constrains:

SOFIA

submm SEDs  photometric

1010 SIRTF redshifts  luminosity function

SCUBA-2 • Redshift (from UIB, H, Ly, or

109

Arp 220: z = 2 [CII] line!) would directly yield,

ALMA Arp 220: z = 3

Lfar-IR, and luminosity function

108

CORNELL 15 meter SIRTF





107

1000 100 10 1 48

Wavelength (m)

LSS: A 3-D baryon map at z  3

Galaxy z-survey and IGM tomography



 Goal:

 to extend detailed 8m studies of galaxies and IGM at z  0-1 to z  2-3.5;

obtain 3-D map of mass and metals and measure clustering statistics for

galaxies and Ly  forest (also proto-clusters, QSOs).

 Galaxies:

 redshift survey down to densities equivalent to L* densities today (crucial

link to present-day galaxy population, now absent).

 Tomography of IGM:

 use multiple sight lines to trace LSS on scales  1 Mpc (since Ly  forest

traces regions within 101 of mean density, and HI optical depth should be a

monotonic function of line-of-sight mass density).

 LSS and galaxy formation:

 the relative distributions of the IGM and the galaxies give the mass

distribution and biases, and together with the locations of metals, strongly

constrain galaxy formation models.



49

LSS: A 3-D baryon map at z  3

Baseline program and requirements



 Baseline program: an SDSS-like survey at z  2-3.5

 z-range because optical z‟s relatively easy,

HI Ly  available, pre-select from optical imaging;

 10 sq.deg. gives few 107 Mpc3 and 5x105 galaxies.

 Telescope/instrument requirements:

 Adaptive optics: „super-natural‟ seeing only (0.3 arcsec

sufficient)

 Multi-fiber spectrograph for IGM: 400-500 fiber MOS can do all

available R  24 IGM probes over 20 FoV; with 10 hours per

pointing can do all 5x104 IGM probes over 10 sq.deg. in 125

nights.

 Multi-slit spectrograph for galaxies: low-resolution (R500)

imaging slit spectrograph doing 500 galaxies over 20 FoV; 2

hours gives 80% completeness to R26.5; 5x105 galaxies over

10 sq.deg. in 250 nights



50

LSS: The emergence of LSS

Studies of proto-clusters



 Step 1 - find proto-clusters (not with GSMT):

 Sunyaev-Zeldovich detections from ground and

satellites (Planck will detect 1 cluster/sq.deg.).

 Clustering from Ly-break sample or z-survey.

 Search around beacons (QSOs, ultra-steep spectrum radio

galaxies).

 Step 2 - measure properties of clusters (and members):

 multi-object spectroscopy to determine membership and

structure

 scale of clusters probably from 1-10 Mpc (i.e. 2-20 arcmin)

 number of bright cluster members probably 10-100 (highly

uncertain)

 Telescope/instrument requirements:

 wide-field MOS with relatively modest multiplex



51

LSS: Evolutionary cosmology

The change in the equation of state



 What is the equation of state for the dark energy?

 For cosmological constant, w  p/  -1 is constant

 For quintessence models, w evolves with redshift

 Method 1 - classical tests with high precision at high z:

 Best option is SNe distances at z  0.5-2 (cf. SNAP satellite).

 Needs wide-field photometry & single-object spectra to J  24-25.

 Method 2 - LSS measurements at high z:

 Can measure w(z) from galaxy power spectrum, the growth

factor (via cluster mass function), or from redshift distortion of

LSS;

 Requires very large (105-106) samples of galaxies at z  1, and

hence widest possible FoV and highest multiplex (8m rather than

30m?)

 What about evolution of fundamental constants (e.g. )

with redshift? Return...

52

Exo-solar Planet Science



 Photometric Direct detection

 Reflected light and/or thermal emission

 Orbital size and inclination  planet mass

 Radii (using transits or albedo & luminosity)

 Spectroscopy

 Composition

 Weather (clouds) and Rotation

 Will involve AO and/or EAO

 Some form of coronagraphy, apodization, and/or nulling

techniques

 Can also use differential techniques (in and out of bands,

etc.)

53

Exosolar Planet Discovery Space

100

4 /D for 30m 20m

@ 1.65 m







10

Mp /Mstar (MJup /Msun )









1









0.1









0.01

1 10 100 1000

Separation (milli-arcseconds) 10-Sep-02



Alternative plot of discovery space for exo-solar planets around stars of 0.2 and 1 Msun.

Lines for signatures of 10-4 and 10-5 arcsec for astrometry and 5 m/s for radial velocities

(30pc, sin i = 1). The vertical line represents the resolution (4/D) of a 30-m telescope at

1.65 m. Included are currently detected exo-solar planets (exoplanets.org). Astrometry

points at different distances are degenerate, but doppler spectroscopy is not. 54

Stellar Populations

 Extending `fossil record‟ studies of resolved stellar

populations to Virgo Cluster galaxies

 CMD studies

 Main-sequence turnoff ages

 [Fe/H] and [Fe/H] spread from RGB morphology

 R=5000 to 50000 spectroscopic studies

 Kinematics

 Detailed chemical compositions

 Directly determine star formation and chemical

evolution histories for very large sample of galaxies

from throughout the Hubble sequence.

 With 10m telescopes, limited to Galaxy, M31 and

their satellites.



55

Point Source

Photometry









Credit: Mike Bolte







56

Debris and Protostellar Disk

Summary

 Dust Continuum Imaging

JCMT 850 m beam

 Spatial resolution: 0.16 - 5”

 Eridani

  0.5 to 16 AU at 3.3 pc

  Eridani Atacama 15 m beams

  30 to 800 AU at 160 pc 350 m

 Ophiuchus

200 m

 Probes dust

 Debris disks: 31 m

 Gaps  resonances

  planets

 Protostellar accretion disks

 infalling material

 Dust properties and mass

 Niche between ALMA and

space missions:

 High spatial resolution

 High surface brightness

sensitivity

Return...

57