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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 formation

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slide1

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 formation
  • 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

ESO

slide2

Millimeter through centimeter astronomy: unveiling the cold, obscured universe

Submm = dust

optical

mid-IR

CO

Galactic

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 formation

HST/CO/SUBMM

slide3

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 FIR

Franceschini 2000

slide4

Radio – FIR: obscuration-free estimate of massive star formation

  • Radio: SFR = 1x10-21 L1.4 W/Hz
  • FIR: SFR = 3x10-10 LFIR (Lo)
slide5

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

7

slide6

Spectral lines

submm

cm

z=0.2

Atomic fine structure lines

z=4

Molecular rotational lines

slide7

Molecular gas

  • CO = total gas masses = fuel for star formation
    • M(H2) = α L’(CO(1-0))
  • Velocities => dynamical masses
  • 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

slide8

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 CNM
  • 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

Fixsen et al.

[CII] CO

[OI] 63um [CII]

[OIII]/[CII]

[OIII] 88um [CII]

Cormier et al.

slide9

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

30’ field at 1.4 GHz

rms< 10uJy, 1” res

High res imaging at 20 to 50 GHz

rms < 0.1 mJy, res < 0.2”

Plateau de Bure Interferometer

High res imaging at 90 to 230 GHz

rms < 0.1mJy, res < 0.5”

slide10

SDSS

Apache Point NM

Massive galaxy and SMBH formation at z~6: gas, dust, star formation in quasar hosts

  • 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)

1148+5251 z=6.42

slide11

Gunn-Peterson Effect

6.4

SDSS z~6 quasars => tail-end of reionization and first (new) light?

z=6.4

5.7

Fan et al 2006

slide12

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)
slide13

Cosmic Downsizing

Massive galaxies form most of their stars rapidly at high z

~(e-folding time)-1

Currently active star formation

tH-1

Red and dead => Require active star formation at early times

Zheng+

  • Massive old galaxies at high z
  • Stellar population synthesis in nearby ellipticals
slide14

Dust in high z quasar host galaxies: 250 GHz surveys

HyLIRG

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 x108Mo
slide15

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)
    • 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

SMC, z<4 quasars

Galactic

z~6 quasar, GRBs

Stratta et al.

slide17

Dust heating? Radio to near-IR SED

low z SED

TD ~ 1000K

TD = 47 K

  • FIR excess = 47K dust
  • SED consistent with star forming galaxy:
  • SFR ~ 400 to 2000 Mo yr-1

Star formation?

AGN

Radio-FIR correlation

slide18

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

1mJy

slide19

CO excitation: Dense, warm gas, thermally excited to 6-5

230GHz

691GHz

starburst nucleus

Milky Way

  • 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
slide20

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

  • => Need gas re-supply to build giant elliptical

SFR

1e3 Mo/yr

Index=1.5

MW

1e11 Mo

Mgas

slide21

1148+52 z=6.42: VLA imaging at 0.15” resolution

CO3-2 VLA

IRAM

0.3”

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
slide22

Gas dynamics => ‘weighing’ the first galaxies

z=6.42

-150 km/s

7kpc

+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
slide23

Gas dynamics: CO velocities

z=4.4

z=4.19

-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
slide24

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?

slide25

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
slide26

[CII] 158um search in z > 6.2 quasars

[CII]

1”

[NII]

For z>6 => redshifts to 250GHz => Bure!

  • S[CII] = 3mJy
  • S250GHz < 1mJy
  • => don’t pre-select on dust
  • L[CII] = 4x109 Lo (L[NII] < 0.1L[CII] )
  • S250GHz = 5.5mJy
  • S[CII] = 12mJy
slide27

1148+5251 z=6.42:‘Maximal star forming disk’

PdBI 250GHz 0.25”res

  • [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
slide28

[CII]

Malhotra

  • [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)
slide29

[CII]

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

slide30

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

slide31

Summary cm/mm observations of 33 quasars at z~6: only direct probe of the host galaxies

EVLA

160uJy

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
slide32

Extreme Downsizing: Building a giant elliptical galaxy + SMBH at tuniv< 1Gyr

10

  • Plausible? Multi-scale simulation isolating most massive halo in 3Gpc3
  • 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

6.5

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
slide33

BREAK

Discussion points:

Dust formation within 1Gyr of Big Bang?

Evolution of MBH – Mbulge relation?

Starburst to quasar sequence: duty cycles and timescales?

Gas resupply (CMA, mergers)?

FIR – EW(Lya) anti-correlation?

ESO

slide34

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
slide35

HI

HII

Loeb & Barkana

slide36

Quasar Near-Zones: sample of 25 quasars at z=5.7 to 6.5

  • (Carilli et al. 2010)
  • Host galaxy redshifts: CO (6), MgII (11), UV (8)
  • 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

slide38

Quasar Near-Zones: RNZ vs redshift

RNZ = 7.3 – 6.5(z-6)

z>6.15

  • <RNZ> decreases by factor 2.3 from z=5.7 to 6.5 =>
  • fHI increases by factor 9
  • Pushing into tail-end of reionization?
slide39

Alternative hypothesis to Stromgren sphere: Quasar Proximity Zones (Bolton & Wyithe)

  • RNZ measures where density of ionizing photon from quasar > background photons (IGRF) =>
  • RNZ [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
slide40

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.

slide41

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
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!

slide43

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

slide45

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 redshifts
slide46

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

embargoed

first light image

slide47

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!
slide48

GN20 molecule-rich proto-cluster at z=4

CO 2-1 in 3 submm galaxies, all in 256 MHz band

0.3mJy

z=4.055

4.051

4.056

0.4mJy

0.7mJy

CO2-1 46GHz

  • SFR ~ 103 Mo/year
  • Mgas > 1010 Mo
  • Early, clustered massive galaxy formation

1000 km/s

slide49

GN20 z=4.0

EVLA: well sampled velocity field

VLA: ‘pseudo-continuum’ 2x50MHz channels

slide50

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
slide51

Most distant SMG: z=5.3 (Riechers et al)

EVLA

Bure

  • CO excitation => ISM conditions
  • nH2 ~ 104.3 cm-3
  • TK ~ 45 K
slide52

CO 1-0 in normal galaxies at z=1.5 (‘sBzK’ galaxies)

EVLA 1-0

Bure 2-1 HST

0.3mJy

4”

500 km/s

  • SFR ~ 10 to 100 Mo/year
  • Find: MH2 > 1010 Mo> Mstars => early stage of MW-type galaxy formation?
  • Again: low order CO is big (28kpc)
  • Milky Way-like CO excitation (low order key!)
  • 10x more numerous than SMGs
slide53

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

slide54

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
slide55

END

Discussion points

  • Stromgren spheres vs. Proximity zones?
  • DGHU, star formation laws, and CO to H2 conversion factors?
  • Role of EVLA/ALMA in first galaxy studies?
slide56

Pushing to normal galaxies: continuum

A Panchromatic view of 1st galaxy formation

100 Mo yr-1 at z=5

cm: Star formation, AGN

(sub)mm Dust, FSL, mol. gas

Near-IR: Stars, ionized gas, AGN

slide57

Comparison to low z quasar hosts

z=6 quasars

IRAS selected

Stacked mm non-detections

PG quasars

Hao et al. 2005

slide59

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

slide60

Milky Way-type gas conditions

Mgas

HyLIRG

1.5

Daddi +

Dannerbauer +

1

SFR

  • CO excitation = Milky Way (but mass > 10xMW)
  • FIR/L’CO  Milky Way
  • Gas depletion timescales > few x108 yrs
slide61

Building a giant elliptical galaxy + SMBH at tuniv< 1Gyr

10

  • 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 high?
  • Gas resupply: not enough to build GE
  • Goal: push to normal galaxies at z > 6 Issues

6.5

Li, Hernquist et al.

slide62

Quasar Near-Zones

Nγ1/3

LUV

  • Correlation of RNZ with UV luminosity
  • No correlation of UV luminosity with redshift