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Radio observations of the formation of the
first galaxies and supermassive Black Holes
Chris Carilli (NRAO)
LANL Cosmology School, July 2010
• Concepts and tools in radio astronomy: dust, cool gas, and star
• Quasar host galaxies at z=6: coeval formation of massive galaxies
and SMBH within 1 Gyr of the Big Bang
• Quasar near-zones and reionization
•Bright future: pushing to normal galaxies with the Atacama Large
Millimeter Array and Expanded Very Large Array – recent examples!
Collaborators: R.Wang, D. Riechers, Walter, Fan, Bertoldi, Menten,
Cox, Strauss, Neri
Millimeter through centimeter astronomy: unveiling the cold,
obscured universe
Submm = dust
GN20 SMG z=4.0
• optical studies provide a limited view of
star and galaxy formation
• cm/mm reveal the dust-obscured, earliest,
most active phases of star and galaxy
Cosmic ‘Background’ Radiation
30 nW m-2 sr-1
17 nW m-2 sr-1
Over half the light in the
Universe is absorbed by
dust and reemitted in the
Franceschini 2000
Radio – FIR: obscuration-free estimate of massive star formation
 Radio: SFR = 1x10-21 L1.4 W/Hz
 FIR:
SFR = 3x10-10 LFIR (Lo)
Magic of (sub)mm: distance independent method of
studying objects in universe from z=0.8 to 10
LFIR ~ 4e12 x S250(mJy) Lo
SFR ~ 1e3 x S250 Mo/yr
FIR = 1.6e12 L_sun
1000 Mo/yr
obs = 250 GHz
Spectral lines
Atomic fine
structure lines
Molecular rotational
Molecular gas
 CO = total gas masses = fuel
for star formation
M(H2) = α L’(CO(1-0))
 Velocities => dynamical
 Gas excitation => ISM physics
(densities, temperatures)
 Dense gas tracers (eg. HCN)
=> gas directly associated with
star formation
 Astrochemistry/biology
Wilson et al.
CO image of ‘Antennae’
merging galaxies
Fine Structure lines
[CII] 158um (2P3/2 - 2P1/2)
 Principal ISM gas coolant:
efficiency of photo-electric
heating by dust grains.
 Traces star formation and the
Fixsen et al.
[OI] 63um [CII]
 COBE: [CII] most luminous
cm to FIR line in the Galaxy ~
1% Lgal
 Herschel: revolutionary look at
FSL in nearby Universe –
AGN/star formation diagnostics
[OIII] 88um [CII]
Cormier et al.
MAMBO at 30m
Powerful suite of existing
cm/mm facilites
First glimpses into early
galaxy formation
30’ field at 250 GHz
rms < 0.3 mJy
Very Large Array
Plateau de Bure Interferometer
30’ field at 1.4 GHz
High res imaging at 90 to 230 GHz
rms< 10uJy, 1” res
rms < 0.1mJy, res < 0.5”
High res imaging at 20 to 50 GHz
rms < 0.1 mJy, res < 0.2”
Massive galaxy and SMBH
formation at z~6: gas, dust,
star formation in quasar hosts
Apache Point NM
Why quasars?
 Rapidly increasing samples:
z>4: > 1000 known
z>5: > 100
z>6: 20
 Spectroscopic redshifts
 Extreme (massive) systems
MB < -26 =>
Lbol > 1014 Lo
MBH > 109 Mo (Eddington / MgII)
SDSS z~6 quasars => tailend of reionization and
first (new) light?
QSO host galaxies
MBH – Mbulge relation
Nearby galaxies
Haaring & Rix
 All low z spheroidal galaxies have SMBH: MBH=0.002 Mbulge
‘Causal connection between SMBH and spheroidal galaxy formation’
 Luminous high z quasars have massive host galaxies (1012 Mo)
Cosmic Downsizing
Massive galaxies form most of their stars rapidly at high z
~(e-folding time)-1
Currently active
star formation
Red and dead =>
Require active star
formation at early
• Massive old galaxies at high z
• Stellar population synthesis in nearby ellipticals
Dust in high z quasar host galaxies: 250 GHz surveys
Wang sample 33
z>5.7 quasars
• 30% of z>2 quasars have S250 > 2mJy
• LFIR ~ 0.3 to 1.3 x1013 Lo (~ 1000xMilky Way)
• Mdust ~ 1.5 to 5.5 x108 Mo
Dust formation at tuniv<1Gyr?
• AGB Winds ≥ 1.4e9yr
 High mass star formation?
(Dwek, Anderson, Cherchneff,
Shull, Nozawa)
 ‘Smoking quasars’: dust formed
in BLR winds (Elvis)
SMC, z<4 quasars
z~6 quasar, GRBs
 ISM dust formation (Draine)
• Extinction toward z=6.2 QSO
and z~6 GRBs => different
mean grain properties at z>4
(Perley, Stratta)
 Larger, silicate + amorphous
carbon dust grains formed in core
collapse SNe vs. eg. graphite
Stratta et al.
Dust heating? Radio to
near-IR SED
 FIR excess = 47K dust
 SED consistent with star
forming galaxy:
SFR ~ 400 to 2000 Mo yr-1
low z SED
TD = 47 K
TD ~ 1000K
Star formation?
Radio-FIR correlation
Fuel for star formation? Molecular gas: 8 CO detections at
z ~ 6 with PdBI, VLA
• M(H2) ~ 0.7 to 3 x1010 (α/0.8) Mo
• Δv = 200 to 800 km/s
CO excitation: Dense, warm gas, thermally excited to 6-5
starburst nucleus
• LVG model => Tk > 50K, nH2 = 2x104 cm-3
• Galactic Molecular Clouds (50pc): nH2~ 102 to 103 cm-3
• GMC star forming cores (≤1pc): nH2~ 104 cm-3
LFIR vs L’(CO): ‘integrated Kennicutt-Schmidt star
formation law’
• Further circumstantial
evidence for star formation
• Gas consumption time
(Mgas/SFR) decreases with SFR
FIR ~ 1010 Lo/yr => tc~108yr
FIR ~ 1013 Lo/yr => tc~107yr
1e3 Mo/yr
1e11 Mo
=> Need gas re-supply to build
giant elliptical
1148+52 z=6.42: VLA imaging at 0.15” resolution
1” ~ 6kpc
 ‘molecular galaxy’ size ~ 6 kpc – only direct observations of host
galaxy of z~6 quasar!
 Double peaked ~ 2kpc separation, each ~ 1kpc
 TB ~ 35 K ~ starburst nuclei
Gas dynamics => ‘weighing’ the first galaxies
-150 km/s
+150 km/s
 CO only method for deriving dynamical masses at these distances
 Dynamical mass (r < 3kpc) ~ 6 x1010 Mo
 M(H2)/Mdyn ~ 0.3
Gas dynamics: CO velocities
-150 km/s
+150 km/s
 Dynamical masses ~ 0.4 to 2 x1011 Mo
 M(H2)/Mdyn ≥ 0.5 => gas/baryons dominate inner few kpc
Break-down of MBH – Mbulge relation at very high z
z>4 QSO CO
z<0.2 QSO CO
Low z galaxies
Riechers +
<MBH/Mbulge> ~ 15 higher at z>4 => Black holes form first?
Wang z=6 sample: galaxy
mass vs. inclination,
assuming all have CO
radii ~ J1148+5251
Wang +
Low z MBH/Mbulge
• Departure from MBH – Mbulge at highest z, or
•All face-on: i < 20o
[CII] 158um search in z > 6.2 quasars
For z>6 => redshifts to 250GHz => Bure!
•L[CII] = 4x109 Lo (L[NII] < 0.1L[CII] )
•S250GHz = 5.5mJy
•S[CII] = 12mJy
• S[CII] = 3mJy
• S250GHz < 1mJy
=> don’t pre-select on dust
1148+5251 z=6.42:‘Maximal star forming disk’
• [CII] size ~ 1.5 kpc => SFR/area ~ 1000 Mo yr-1 kpc-2
• Maximal starburst (Thompson, Quataert, Murray 2005)
 Self-gravitating gas and dust disk
 Vertical disk support by radiation pressure on dust grains
‘Eddington limited’ SFR/area ~ 1000 Mo yr-1 kpc-2
 eg. Arp 220 on 100pc scale, Orion SF cloud cores < 1pc
• [CII]/FIR decreases with
LFIR = lower gas heating
efficiency due to charged
dust grains in high
radiation environments
• Opacity in FIR may also
play role (Papadopoulos)
z >4
• HyLIRG at z> 4: large
scatter, but no worse than
low z ULIRG
• Normal star forming
galaxies are not much
harder to detect in [CII]
(eg. LBG, LAE)
Maiolino, Bertoldi, Knudsen,
Iono, Wagg
A starburst to quasar
sequence at the highest z?
Anticorrelation of EW(Lya)
with submm detections
No Dust
Submm dust
• Strong FIR => starburst
• Weak Lya => young quasar, prior to build-up of BLR (?)
• Consistent with ‘Sanders sequence’: starburst to composite to quasar
Submm dust
No Dust
Summary cm/mm observations
of 33 quasars at z~6: only
direct probe of the host galaxies
J1425+3254 CO at z = 5.9
 11 in mm continuum => Mdust ~ 108 Mo: Dust formation in SNe?
 10 at 1.4 GHz continuum: Radio to FIR SED => SFR ~ 1000 Mo/yr
 8 in CO => Mgas ~ 1010 Mo = Fuel for star formation in galaxies
 High excitation ~ starburst nuclei, but on kpc-scales
 Follow star formation law (LFIR vs L’CO): tc ~ 107 yr
 3 in [CII] => maximal star forming disk: 1000 Mo yr-1 kpc-2
 Departure from MBH – Mbulge at z~6: BH form first?
 Anticorrel. EW(Lya) with submm detections => SB to Q sequence
Extreme Downsizing: Building a
giant elliptical galaxy + SMBH at
tuniv< 1Gyr
 Plausible? Multi-scale simulation
isolating most massive halo in 3 Gpc3
 Stellar mass ~ 1e12 Mo forms in series
(7) of major, gas rich mergers from z~14,
with SFR  1e3 Mo/yr
 SMBH of ~ 2e9 Mo forms via
Eddington-limited accretion + mergers
 Evolves into giant elliptical galaxy in
massive cluster (3e15 Mo) by z=0
Li, Hernquist et al.
Li, Hernquist+
• Rapid enrichment of metals, dust in ISM
• Rare, extreme mass objects: ~ 100 SDSS z~6 QSOs on entire sky
• Goal: push to normal galaxies at z > 6
Discussion points:
1.Dust formation within 1Gyr of Big Bang?
2.Evolution of MBH – Mbulge relation?
3.Starburst to quasar sequence: duty cycles and
4.Gas resupply (CMA, mergers)?
5.FIR – EW(Lya) anti-correlation?
Quasar Near Zones: J1148+5251
• Accurate host galaxy redshift from CO: z=6.419
• Quasar spectrum => photons leaking down to z=6.32
White et al. 2003
• ‘time bounded’ Stromgren sphere ionized by quasar
• Difference in zhost and zGP =>
RNZ = 4.7Mpc
[fHI Nγ tQ]1/3 (1+z)-1
Loeb & Barkana
Quasar Near-Zones: sample of 25 quasars at z=5.7 to 6.5
(Carilli et al. 2010)
I.Host galaxy redshifts: CO (6), MgII (11), UV (8)
I.GP on-set redshift:
•Adopt fixed resolution of 20A
•Find 1st point when transmission drops below 10% (of extrapolated) = well
above typical GP level.
z = 6.1
Wyithe et al. 2010
Quasar Near-Zones: Correlation of RNZ with UV luminosity
Quasar Near-Zones: RNZ vs redshift
RNZ = 7.3 – 6.5(z-6)
•<RNZ> decreases by factor 2.3 from z=5.7 to 6.5 =>
fHI increases by factor 9
• Pushing into tail-end of reionization?
Alternative hypothesis to Stromgren sphere: Quasar Proximity
Zones (Bolton & Wyithe)
• RNZ measures where density of ionizing photon from quasar >
background photons (IGRF) =>
[Nγ]1/2 (1+z)-9/4
• Increase in RNZ from z=6.5 to 5.7 is then
due to rapid increase in mfp and density of
ionizing background during overlap or
‘percolation’ stage of reionization
• Either case (CSS or PZ) => rapid
evolution of IGM from z ~ 6 to 6.5
What is Atacama Large Milllimeter Array?
North American, European, Japanese, and Chilean collaboration to build &
operate a large millimeter/submm array at high altitude site (5000m) in
northern Chile => order of magnitude, or more, improvement in all areas of
(sub)mm astronomy, including resolution, sensitivity, and frequency coverage.
ALMA Specs
• High sensitivity array = 54x12m
• Wide field imaging array = 12x7m antennas
• Frequencies = 80 GHz to 720 GHz
• Resolution = 20mas res at 700 GHz
• Sensitivity = 13uJy in 1hr at 230GHz
What is EVLA? First steps to the SKA-high
By building on the existing infrastructure, multiply ten-fold the
VLA’s observational capabilities, including:
 10x continuum sensitivity (1uJy)
 Full frequency coverage (1 to 50 GHz)
 80x Bandwidth (8GHz) + 104 channels
 40mas resolution at 40GHz
Overall: ALMA+EVLA provide > order magnitude
improvement from 1GHz to 1 THz!
Pushing to normal galaxies: spectral lines
100 Mo yr-1 at z=5
cm telescopes: star formation, low
order molecular transitions -- total
gas mass, dense gas tracers
(sub)mm: dust, high order
molecular lines, fine
structure lines -- ISM
physics, dynamics
ALMA and first galaxies: [CII] and Dust
Wide bandwidth spectroscopy
J1148+52 at z=6.4 in
24hrs with ALMA
• ALMA: Detect multiple lines, molecules per 8GHz band
• EVLA 30 to 38 GHz = CO2-1 at z=5.0 to 6.7 => large cosmic volume
searches for molecular gas (1 beam = 104 cMpc3) w/o need for optical
ALMA Status
•Antennas, receivers, correlator in production: best submm receivers
and antennas ever!
•Site construction well under way: Observation Support Facility,
Array Operations Site, 5 Antenna interferometry at high site!
• Early science call Q1 2011
first light image
EVLA Status
• Antenna retrofits 70% complete (100% at ν ≥ 18GHz).
• Full receiver complement completed 2012 with 8GHz bandwidth
• Early science started March 2010 using new correlator (up to 2GHz
bandwidth) – already revolutionizing our view of galaxy formation!
GN20 molecule-rich proto-cluster at z=4
CO 2-1 in 3 submm galaxies, all in 256 MHz band
• SFR ~ 103 Mo/year
• Mgas > 1010 Mo
• Early, clustered massive
galaxy formation
1000 km/s
GN20 z=4.0
VLA: ‘pseudo-continuum’
2x50MHz channels
EVLA: well sampled velocity field
GN20 moment images
+250 km/s
-250 km/s
• Low order CO emitting regions are large (10 to 20 kpc)
• Gas mass = 1.3e11 Mo
• Stellar mass = 2.3e11 Mo
• Dynamical mass (R < 4kpc) = 3e11 Mo
=> Baryon dominated within 4kpc
Most distant SMG: z=5.3 (Riechers et al)
CO excitation => ISM conditions
• nH2 ~ 104.3 cm-3
• TK ~ 45 K
CO 1-0 in normal galaxies at z=1.5 (‘sBzK’ galaxies)
Bure 2-1
EVLA 1-0
500 km/s
• SFR ~ 10 to 100 Mo/year
• Find: MH2 > 1010 Mo> Mstars => early stage of MWtype galaxy formation?
• Again: low order CO is big (28kpc)
• Milky Way-like CO excitation (low order key!)
•10x more numerous than SMGs
Dense gas history of the Universe: the ‘other half’ of galaxy formation
 Tracing the fuel for galaxy formation over cosmic time
Millennium Simulations
Obreschkow & Rawlingn
SF law
Major observational goal for next decade
EVLA/ALMA Deep fields: 1000hr, 50 arcmin2
• Volume (EVLA, z=2 to 2.8) = 1.4e5 cMpc3
• 1000 galaxies z=0.2 to 6.7 in CO with M(H2) > 1010 Mo
• 100 in [CII] z ~ 6.5
• 5000 in dust continuum
Discussion points
1.Stromgren spheres vs. Proximity zones?
2.DGHU, star formation laws, and CO to H2
conversion factors?
3.Role of EVLA/ALMA in first galaxy studies?
Pushing to normal galaxies: continuum
A Panchromatic view of 1st galaxy formation
100 Mo yr-1 at z=5
cm: Star formation,
(sub)mm Dust,
FSL, mol. gas
Near-IR: Stars,
ionized gas, AGN
Comparison to low z quasar hosts
z=6 quasars
IRAS selected
Stacked mm
PG quasars
Hao et al. 2005
Molecular gas mass: X factor
M(H2) = X L’(CO(1-0))
Milky way: X = 4.6 MO/(K km/s pc^2) (virialized GMCs)
ULIRGs: X = 0.8 MO/(K km/s pc^2) (CO rotation curves)
 Optically thin limit: X ~ 0.2
Downes + Solomon
Milky Way-type gas conditions
Dannerbauer +
Daddi +
 CO excitation = Milky Way (but mass > 10xMW)
 FIR/L’CO  Milky Way
 Gas depletion timescales > few x108 yrs
Building a giant elliptical galaxy + SMBH at tuniv< 1Gyr
• Rapid enrichment of metals, dust in ISM
• Rare, extreme mass objects: ~ 100 SDSS z~6 QSOs on entire sky
Issues and questions:
• Duty cycle for star formation and SMBH accretion very
6.5 high?
• Gas resupply: not enough to build GE
• Goal: push to normal galaxies at z > 6Li,
Hernquist et al.
Quasar Near-Zones
• Correlation of RNZ with UV luminosity
• No correlation of UV luminosity with redshift