ESO
ALMA, EVLA, and the Origin of Galaxies(Dense Gas History of the Universe)
Chris Carilli (NRAO)Bonn, Germany, September 2010
• The power of radio astronomy: dust, cool gas, and star formation
• Current State-of-Art z ~ 6: Quasar host galaxies = early formation of massive galaxies and SMBH z ~ 1 to 3: Normal galaxy formation during the epoch of galaxy assembly = probing the ‘Gas Rich Universe’
• Bright (near!) future: The Atacama Large Millimeter Array (and CCAT!) and Expanded Very Large Array – recent example!
Thanks: Wang, Riechers, Walter, Fan, Bertoldi, Menten, Cox, Daddi, Schinnerer, Pannella, Aravena, Smolcic, Neri, Dannerbauer…
Star formation history of the Universe (mostly optical view)
‘epoch of galaxy assembly’
~50% of present day stellar mass produced between z~1 to 3
Bouwens +
First light + cosmic reionization
Star formation as function of stellar mass
tH-1tH-1
‘active star formation’
‘red and dead’
Zheng ea
‘Downsizing’: Massive galaxies form most of stars quickly, at high z
(see also: stellar pop. synthesis at low z; evolved galaxies at z ~1 to 2)
specific SFR = SFR/M* ~
e-folding time-1
Optical Limitation 1: Dust
Bouwens +
Optical Limitation 2: Cold gas = fuel for star formation (‘The missing half of galaxy formation’)
Low z spirals
Integrated Kennicutt-Schmidt star formation law: relate SFR and gas content of galaxies
Power-law index = 1.5‘SFR’
‘Mgas’
Millimeter through centimeter astronomy: unveiling the cold, obscured universe
• cm/mm reveal the dust-obscured, earliest, most active phases of star formation in galaxies• cm/mm reveal the cool gas that fuels star formation
HST/CO/SUBMM
CO
Wilson et al.
CO image of ‘Antennae’ merging galaxies
GN20 z=4 submm galaxy
Radio – FIR: obscuration-free estimate of massive star formation
Radio: SFR = 1x10-21 L1.4 W/Hz
FIR: SFR = 3x10-10 LFIR (Lo)
Spectral lines
Molecular rotational lines
Atomic fine structure lines
z=0.2
z=4
cm submmMolecular gas
• CO = total gas mass tracer
M(H2) = α L’(CO(1-0))
• Velocities => dyn. mass
• Gas excitation => ISM physics (densities, temperatures)
• Astrochemistry/biology, eg. dense gas tracers (HCN) directly associated with star formation (Smail, van Dishoeck)
•Gas supply: smooth accretion or major gas rich mergers?
Fine Structure lines
[CII] 158um (2P3/2 - 2P1/2)
Principal ISM gas coolant: photo-electric heating by dust
Traces star forming regions and the CNM
[CII] most luminous line from meter to FIR, up to 1% Lgal
Herschel: revolutionary look at FSL in nearby Universe – AGN/star formation diagnostics (Hailey-Dunsheath)
[CII] CO [OI] 63um [CII]
[OIII] 88um [CII][OIII]/[CII]
Cormier et al.
Fixsen et al.
Plateau de Bure Interferometer
High res imaging at 90 to 230 GHz
rms < 0.1mJy, res < 0.5”
MAMBO at 30m
(Cox)
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
Theme I: Massive galaxy and SMBH formation at z~6 – Quasar hosts at tuniv<1Gyr
Why quasars?
Rapidly increasing samples: z>4: > 1000 known
z>5: > 100
z>6: 20
Spectroscopic redshifts
Extreme (massive) systems: Lbol ~1014 Lo=> MBH~ 109 Mo => Mbulge ~ 1012 Mo
Downsizing: study of very early massive galaxy formation intrinsically interesting
1148+5251 z=6.42
SDSSApache Point NM
• 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, Valiante)
HyLIRG
Dust in high z quasar host galaxies
30% of z>2 quasars have S250 > 2mJy
Wang sample 33 z>5.7 quasars
MAMBO 30m 250GHz surveys
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/s• Accurate host galaxy redshifts
1mJy
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 (Papadopoulos, Smail)
LFIR vs L’(CO): 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
SFR
Mgas
MW
Size ~ 6 kpc, with two peaks ~ 2kpc separation
Dynamical mass (r < 3kpc) ~ 6 x1010 Mo
M(H2)/Mdyn ~ 0.3
Imaging => dynamics => weighing the first galaxies
z=6.42
-150 km/s
+150 km/s
7kpc
1” ~ 5.5kpc
CO3-2 VLA
+
0.15” TB ~ 25K
PdBI
Break-down of MBH – Mbulge relation at very high z
z>4 QSO CO
z<0.2 QSO CO
Low z galaxies
MBH ~ 0.002Mbulge
<MBH/Mbulge> ~ 15 higher at z>4 => Black holes form first?
(Maiolino)
•‘Causal connection between galaxy and SMBH formation’
• At high z, CO only method to derive Mbulge
For z>6 => redshifts to 250GHz => Bure! (Knudsen)
1”
[CII]
[NII]
Fine Structure Lines: [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 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
PdBI 250GHz 0.25”res
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
Departure from MBH – Mbulge at z~6: BH form first?
3 in [CII] => maximal star forming disk: 1000 Mo yr-1 kpc-2
J1425+3254 CO at z = 5.9
Theme I summary: cm/mm observations of 33 quasars at z~6 – only direct probe of the host galaxies
EVLA160uJy
Building a giant elliptical galaxy + SMBH at tuniv< 1Gyr (‘extreme downsizing’)
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 high redshift
Li, Hernquist et al. Li, Hernquist+
HST
Theme II: ‘Normal’ star forming galaxies during epoch of galaxy assembly (‘sBzK’ at z ~ 2)
color-color diagrams identify thousands of z~ 2 star forming galaxies
near-IR selected => ‘stellar mass limited sample’: M* ~ 1010 to 1011Mo
Common ~ few x10-4 Mpc-3 (5 arcmin-2)
• HST imaging => disk sizes ~ 1” ~ 8kpc, punctuated by massive star forming regions
<SFR> = 96 Mo yr-1 [FIR ~ 3e11 Lo]
VLA size ~ 1” ~ HST
Pannella +
<S1.4> = 8.8 +/- 0.1 uJy
Unbiased star formation rates in z~2 sBzK
VLA 1.4GHz stacking: 30,000 in COSMOS
COSMOS 2 deg2 Deep Field (Scoville ea)
• Approaching SDSS volume at z > 1
• 2e6 galaxies from z~ 0 to 7
(Decarli)
SFR ~ independent of blue magnitude
SFR increases with B-z => dust extinction increases with SFR (or M*)
SFR increases with stellar mass
Stacking in bins of 30001010 Mo 3x1011 Mo
Dawn of Downsizing: SFR/M* vs. M* (Karim)
5x
tH-1 (z=1.8)
z=0.3
1.4GHz SSFR
z=1.5
z=2.1
UV SSFR
SSFR constant with M*, unlike z<1=> ‘pre-downsizing’ ~ constant efolding time
z>1.5 sBzK well above the ‘red and dead’ galaxy line => even large growing exponentially
UV dust correction = f(SFR, M*) [factor 5 at 2e10 Mo ~ LBG (Shapely+ 01)]
CO observations with Bure: Massive gas reservoirs without extreme starbursts (Daddi ea 2009)
6 of 6 sBzK detected in CO
Gas mass ~ 1011 Mo ~ gas masses in high z HyLIRG
but
SFR < 10% HyLIRG
Gas masses ≥ stellar masses => pushed back to epoch when galaxies are gas dominated!
Lower CO excitation: low J observations are key!
FIR/L’CO: Gas consumption timescales >= few x108 yrs
HyLIRG
Closer to Milky Way-type gas conditions (Dannerbauer)
1
1.5
Summary Theme II: Probing the Gas Rich Universe = Gas dominated, normal galaxy formation at z ~2
SSFR constant with M*: ‘pre-downsizing’
Well above ‘red + dead’ curve up to 1011 M*
Gas masses ~ 1011 Mo ≥ stellar masses
Gas consumption time > few x108 yrs
‘Secular (spiral) galaxy formation during epoch of galaxy assembly’
Great promise for ALMA + EVLA!
Genzel + 08
What is the EVLA? similar ten-fold improvement in most areas of cm astronomy
•frequencies = 1 to 50 GHz
•8 GHz BW => 80x old
•res = 40mas res at 43GHz
•rms = 6uJy in 1hr at 30GHz
What is ALMA? Tenfold improvement (or more), in all areas of (sub)mm astronomy, including resolution, sensitivity, and frequency coverage.
•antennas: 54x12m, 12x7m antennas
•frequencies: 80 GHz to 720 GHz
•res = 20mas res at 700 GHz
•rms = 13uJy in 1hr at 230GHz
ALMA+EVLA ~ Order magnitude improvement from 1GHz to 1 THz!
(Testi)
(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
100 Mo yr-1 at z=5
Pushing to normal galaxies
EVLA 1.4 GHz continuum: thousands of sBzK galaxies
ALMA and first galaxies: [CII]
100Mo/yr
10Mo/yr
ALMA ‘redshift machine’: [CII] in z>7 dropouts
Wide bandwidth spectroscopy
• ALMA: Detect multiple lines, molecules per 8GHz band = real astrochemistry
• 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
J1148+52 at z=6.4 in 24hrs with ALMA
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
EVLA Status
•Antenna retrofits 70% complete (100% at ν ≥ 18GHz).
•Early science in March 2010 using new correlator (2GHz)
•Full receiver complement completed 2012 + 8GHz
5 antennas on high site
GN20 molecule-rich proto-cluster at z=4CO 2-1 in 3 submm galaxies, all in 256 MHz band
4.051
z=4.055
4.056
0.4mJy
1000 km/s
0.3mJy
• SFR ~ 103 Mo/year
• Mgas ~ 1011 Mo
• Early, clustered massive galaxy formation
+250 km/s
-250 km/s
Dense gas history of the Universe Tracing the fuel for galaxy formation over cosmic time
Millennium Simulations Obreschkow & Rawlings
SF Law
Primary goal for studies of galaxy formation in next decade!
SFR
Mgas
EVLA/ALMA Deep fields: the‘missing half’ of galaxy formation
• 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
Millennium Simulations Obreschkow & Rawlings
ESO
END
CCAT: wide field ‘finder’ surveys
