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Transcript of ESO
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Radio observations of the formation of the first galaxies and supermassive Black Holes
Chris Carilli (NRAO)Purple Mountain Observatory, May 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
• Bright (and near!) future: Atacama Large Millimeter Array and the Expanded Very Large Array
Collaborators: R.Wang, D. Riechers, Walter, Fan, Bertoldi, Menten, Cox, Strauss, Neri
Millimeter through centimeter astronomy: unveiling the cold, obscured universe
GN20 SMG z=4.0
Galactic
Submm = dustoptical CO
• 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
mid-IR
Cosmic ‘Background’ Radiation
Franceschini 2000
Over half the light in the Universe is absorbed and reemitted in the FIR
30 nW m-2 sr-1
17 nW m-2 sr-1
Radio – FIR: obscuration-free estimate of massive star formation
Radio: SFR = 10-21 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
obs = 250 GHz
1000 Mo/yr
Spectral lines
Molecular rotational lines
Atomic fine structure lines
z=0.2
z=4
cm submm
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
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
[CII] CO [OI] 63um [CII]
[OIII] 88um [CII][OIII]/[CII]
Cormier et al.
Plateau de Bure Interferometer
High res imaging at 90 to 230 GHz
rms < 0.1mJy, res < 0.5”
MAMBO at 30m
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”
Powerful suite of existing cm/mm facilites
First glimpses into early galaxy formation
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
SDSSApache Point NM
Gunn Peterson trough => pushing into cosmic reionization = first galaxies, black holes
First galaxies and SMBH: z>6 => tuniv < 1 Gyr
1148+5251 z=6.42
QSO host galaxies – MBH -- Mbulge relation
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)
Haaring & Rix
Nearby galaxies
Cosmic Downsizing
Massive galaxies form most of their stars rapidly at high z
tH-1tH-1
Currently active star formation
Red and dead => Require active star formation at early times
Zheng+
~(e-folding
time)-1
• Massive old galaxies at high z• Stellar population synthesis in nearby ellipticals
• 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
HyLIRG
Dust in high z quasar host galaxies: 250 GHz surveys
Wang sample 33 z>5.7 quasars
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)
• Extinction toward z=6.2 QSO and z~6 GRBs => different mean grain properties (Perley, Stratta)
Larger, silicate + amorphous carbon dust grains formed in core collapse SNe vs. eg. graphite
Stratta et al.
z~6 quasar, GRBs
Galactic
SMC, z<4 quasars
Dust heating? Radio to near-IR SED
TD = 47 K FIR excess = 47K dust
SED consistent with star forming galaxy:
SFR ~ 400 to 2000 Mo yr-1 Radio-FIR correlation
low z SED
TD ~ 1000K
Star formation?
AGN
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/s1mJy
CO excitation: Dense, warm gas, thermally excited to 6-5
• 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
Milky Way
starburst nucleus
230GHz 691GHz
LFIR vs L’(CO): ‘integrated Kennicutt-Schmidt star formation law’
Index=1.5
1e11 Mo
1e3 Mo/yr
• Further circumstantial evidence for star formation
• Gas consumption time (Mgas/SFR) decreases with SFRFIR ~ 1010 Lo/yr => tc~108yrFIR ~ 1013 Lo/yr => tc~107yr
=> Need gas re-supply to build giant elliptical
SFR
Mgas
MW
1148+52 z=6.42: VLA imaging at 0.15” resolution
IRAM
1” ~ 6kpc
CO3-2 VLA
‘molecular galaxy’ size ~ 6 kpc
Double peaked ~ 2kpc separation, each ~ 1kpc
TB ~ 35 K ~ starburst nuclei
+0.3”
CO only method for deriving dynamical masses at these distances
Dynamical mass (r < 3kpc) ~ 0.4 to 2 x1011 Mo
M(H2)/Mdyn ≥ 0.1 to 0.5 => gas/baryons dominate inner few kpc
Gas dynamics => ‘weighing’ the first galaxies
z=6.42
-150 km/s
+150 km/s
7kpc
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?
For z>6 => redshifts to 250GHz => Bure!
1”
[CII]
[NII]
[CII] 158um search in z > 6.2 quasars
•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 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
PdBI 250GHz 0.25”res
[CII]
• [CII]/FIR decreases with LFIR = lower gas heating efficiency due to charged dust grains => luminous starbursts are still hard to detect in [CII]
• Opacity in FIR may also play role (Papadopoulos)
Malhotra, Maiolino, Bertoldi, Knudsen, Iono, Wagg…
[CII]
• HyLIRG at z> 4: large scatter, but no worse than low z ULIRG
• Normal star forming galaxies are not much harder to detect
Malhotra, Maiolino, Bertoldi, Knudsen, Iono, Wagg…
z >4
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
Follow star formation law (LFIR vs L’CO): tc ~ 107 yr
3 in [CII] => maximal star forming disk: 1000 Mo yr-1 kpc-2
Confirm decrease in RNZ with increasing z
J1425+3254 CO at z = 5.9
Summary cm/mm observations of 33 quasars at z~6: only direct probe of the host galaxies
J1048 z=6.23 CO w. PdBI, VLA
Building a giant elliptical galaxy + SMBH at tuniv< 1Gyr
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
6.5
10
• 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
Li, Hernquist et al.
Li, Hernquist+
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)
40mas resolution at 40GHz
Overall: ALMA+EVLA provide > order magnitude improvement from 1GHz to 1 THz!
(sub)mm: dust, high order molecular lines, fine structure lines -- ISM physics, dynamics
cm telescopes: star formation, low order molecular transitions -- total gas mass, dense gas tracers
Pushing to normal galaxies: spectral lines
100 Mo yr-1 at z=5
ALMA and first galaxies: [CII] and Dust
100Mo/yr
10Mo/yr
Wide bandwidth spectroscopy
• 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 (1 beam = 104 cMpc3)
J1148+52 at z=6.4 in 24hrs with ALMA
EVLA Status
•Antenna retrofits 70% complete (100% at ν ≥ 18GHz).
•Early science in March 2010 using new correlator (2GHz)
•Full receiver complement completed 2012 with 8GHz bandwidth
EVLA Early Science Results: GN20 molecule-rich proto-
cluster at z=4
4.051
z=4.055
4.052
0.7mJyCO2-1 46GHz
0.4mJy
1000 km/s
GN20z=4.0
+250 km/s
-250 km/s
ALMA Status•Antennas, receivers, correlator in production: best submm receivers and antennas ever!•Site construction well under way: Observation Support Facility, Array Operations Site, 3 Antenna interferometry at high site!• Early science call Q1 2011
embargoed
first light image
END
cm: Star formation, AGN
(sub)mm Dust, FSL, mol. gas
Near-IR: Stars, ionized gas, AGN
Pushing to normal galaxies: continuum
A Panchromatic view of 1st galaxy formation
100 Mo yr-1 at z=5
Comparison to low z quasar hosts
IRAS selected
PG quasars
z=6 quasars
Stacked mm non-detections
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