History of IGM
• bench-mark in cosmic structure formation indicating the first luminous structures
Epoch of Reionization (EoR)
z=5.80
z=5.82
z=5.99
z=6.28
The Gunn Peterson Effect
Fan et al 2003
Fast reionization at z=6.3
=> opaque at _obs<0.9m
f(HI) > 0.001 at z = 6.3
Neutral IGM evolution (Gnedin 2000): ‘Cosmic Phase transition’
HI fraction
Density Gas Temp
Ionizing intensity
Normalization: GP absorption, LCDM + z=4 LBGs, T_IGM
8 Mpc (comoving)
• Large scale structure (10’s deg) = Thompson scattering at EoR
• e =Ln_ee = 0.17
=> F(HI) < 0.5 at z=20
WMAP Large scale polarization of CMB (Kogut et al.)
GP + WMAP => Reionization Process is complex, extending from z~20-6? (200-800 Million years after Big Bang)
Fan et al. 2002
Near-edge of reionization: GP Effect
Fairly Fast:• f(HI) > 1e-3 at z >= 6.4 (0.87Gyr)• f(HI) < 1e-4 at z <= 5.7 (1.0 Gyr)
• Problem: _Lya >> 1 for f(HI) > 0.001
Complex reionization example: Double reionization? (Cen 2002)
Pop III stars in ‘mini-halos’ (<1e7 M_sun)‘normal’ galaxies
(>1e8M_sun)
Radio astronomical probes of the Epoch of Reionization and the 1st luminous objects
1. Objects within EoR – Molecular gas, dust, star formation
2. Neutral IGM – HI 21cm emission and absorption
Collaborators
USA – Carilli, Walter, Fan, Strauss, Owen, Gnedin, Djorgovski
Euro – Bertoldi, Menten, Cox, Omont, Beelen
SKA ‘level 0’ science team – Briggs, Carilli, Furlanetto, Gnedin
MAMBO + IRAM 30m
Max-Planck Bolometer array: 133 pixel bolometer camera at 300mK, single mode horns (Kreysa)
Wide fieldimaging and photometry at 250 GHz
rms < 0.5 mJy, res=10.6”, field sizes >= 30’
1. Wide-field imaging at 1.4 GHz: rms=7uJy, 1” res, FoV=30’
Astrometry => avoid confusion
Imaging => AGN vs. Starburst, Lensing?
cm-to-mm SEDs => redshifts, star formation rates unhindered by dust
2. Low order CO transitions at 20 to 50 GHz: rms < 0.1 mJy, res << 1”
Gas excitation and mass estimates
Gas distribution and dynamics, Lensing?
Very Large Array
Plateau de Bure Interferometer
Imaging high order CO lines at 90 to 230 GHz: rms < 0.5 mJy, res < 1” (15% of collecting area of ALMA)
Magic of (sub)mm
350 GHz
250 GHz
L_FIR = 4e12 x S_250(mJy) L_sun for z=0.5 to 8
SFR = 1400 x S_250 M_sun/yr
M_dust = 1.4e8 x S_250 M_sun
SDSS + DPOSS:
700 at z > 4
30 at z > 5
7 at z > 6
M_B < -26 =>
L_bol > 1e14 L_sun
M_BH > 1e9 M_sun
Hunt 2001
High redshift QSOs
QSO host galaxies – M_BH – relation
• Most (all?) low z spheroidal galaxies have SMBH
• M_BH = 0.002 M_bulge
‘Causal connection between SMBH and spheroidal galaxy formation’ (Gebhardt et al. 2002)?
Luminous high z QSOs have massive host galaxies (1e12 M_sun)
• 30% of luminous QSOs have S_250 > 2 mJy, independent of redshift from z=1.5 to 6.4
• L_FIR =1e13 L_sun = 0.1 x L_bol: Dust heating by starburst or AGN?
MAMBO surveys of z>2 DPSS+SDSS QSOs
1148+52 z=6.4
1048+46 z=6.2
1e13L_sun
Arp220
L_FIR vs L’(CO)
M(H_2) = X * L’(CO), X=4 (Milkyway), X=0.8 (ULIRGs)
Telescope time: t(dust) = 1hr, t(CO) = 10hr
Index=1.7
Index=1
1e11 M_sun
•highest redshift quasar known•L_bol = 1e14 L_sun•central black hole: 1-5 x 109 Msun (Willot etal.)•clear Gunn Peterson trough (Fan etal.)
Objects within EoR: QSO 1148+52 at z=6.4
1148+52 z=6.42: MAMBO detection
S_250 = 5.0 +/- 0.6 mJy => L_FIR = 1.2e13 L_sun,
M_dust =7e8 M_sun
3’
VLA Detection of Molecular Gas at z=6.419
46.6149 GHzCO 3-2
Off channels
50 MHz ‘channels’ (320 kms-1, z=0.008)noise: ~57 Jy, D array, 1.5” beam
M(H_2) = 2e10 M_sun
Size < 1.5” (image),
Size > 0.2” (T_B/50K)^-1/2
IRAM Plateau de Bure confirmation
• FWHM = 305 km/s• z = 6.419 +/- 0.001
(3-2)
(7-6)
(6-5)
• Tkin=100K, nH2=105cm-3
VLA imaging of CO3-2 at 0.5” and 0.15” resolution
Separation = 0.3” = 1.7 kpc
T_B = 20K = T_B (starburst)
Merging galaxies?
Or Dissociation by QSO?
rms=50uJy at 47GHz
CO extended to NW by 1” (=5.5 kpc) tidal(?) feature
T_B = 3 K = Milky way
Phase stability: Fast switching at the VLA
10km baseline rms = 10deg
1148+52: starburst+AGN?
SFR(>5 M_sun) = 1400 M_sun/year => host spheroid formation in 5e7 yrs at z > 6?
SMBH formation: n x 2.4e7 yr (Loeb, Wyithe,…)
=> Coeval formation of galaxy/SMBH at z>6?
S_1.4= 55 +/- 12 uJy IRAS 2Jy sample (Yun+)
1148+52
1048+46
•M(dust) = 7e8 M_sun
•M(H_2) = 2e10 M_sun
•M_dyn (r=2kpc) = 4e10 (sin i)-2 M_sun
•M_BH = 3e9 M_sun
M_BH– => M_bulge = 1.5e12 M_sun
• Gas/dust = 30, typical of starburst
• Dynamical vs. gas mass => baryon dominated?
• Dynamical vs. ‘bulge’ mass => M –breaks-down at high z? Or face-on (i < 9deg)?
1148+52: Masses
Cosmic (proper) time
T_univ
• Age of universe: 8.7e8 yr
• C, O production (3e7 M_sun): 1e8 yr
• Fe production (SNe Ia): few e8 yr (Maiolino, Freudling)
• Dust formation: 1.4e9yr (AGB winds) => dust formed in high mass stars/SNR (Dunne et al.. 2003)? => silicate grains?
=> Star formation started early (z > 10)?
Timescales
Cosmic Stromgren Sphere
• Accurate redshift from CO: z=6.419 optical high ionization lines can be off by 1000s km s-1
• Proximity effect: photons leaking from 6.32<z<6.419
z=6.32
•Ionized sphere around QSO: R = 4.7 Mpc ‘time bounded’ Stromgren sphere:
t_qso= 1e5 R^3 f(HI)= 1e7yrs
White et al. 2003
Loeb & Rybicki 2000
Constraints on neutral fraction at z=6.4 GP => f(HI) > 0.001
If f(HI) = 0.001, then t_qso = 1e4 yrs – implausibly short? (see also J1030+0524 z=6.28, J1048+46 z=6.23 using MgII lines)
Probability arguments suggest: f(HI) > 0.1 at z=6.4 – much better limit than GP
Wyithe and Loeb 2003
f_lt = 1e7 yr
Gravitational Lensing?
CO 3-2 double source, 0.3” separation => strong lensing?
Keck near IR imaging: point source < 0.5” at K (Djorgovski)
HST/ACS imaging: point source < 0.3” (Richards 2004)
Radio continuum: Foreground cluster (30x over-density) at z=0.05 => magnification by 2x?
1148+5251
Fan et al. 2002
Near-edge of reionization: GP + Strom. Spheres
Very Fast?• f(HI) > 1e-1 at z >= 6.4 (0.87Gyr)• f(HI) < 1e-4 at z <= 5.7 (1.0 Gyr)
Gas and dust in the first galaxies
• Luminous (star forming?) galaxy: Far IR luminosity = 1e13 Lsun at z=6.42
• Merging(?) galaxy: Molecular gas mass = 2x1010 M_sun, M_dyn = 4e10 (sin i)-2 M_sun
• Early enrichment of heavy elements and dust produced in the first stars => star formation commenced at 0.4 Gyr after the big bang
• Coeval formation of SMBH + stars in earliest galaxies (break-down of M- at high z?)
• Cosmic Stromgren sphere of 4.7 Mpc => ‘witnessing process of reionization’ t_qso = 1e7 * f(HI) yrs ‘fast’ reionization: f(HI)>0.1 at z=6.4?
J1048+4637: A second FIR-luminous QSO source at z=6.2
3.0 +/- 0.4 mJy => L_FIR = 7.5e12 L_sun
M_dust = 4e8 M_sun
Cloverleaf z=2.56, Grav. Lens mag. 11x
VLA detection of HCN emission at 22 GHz => n(H_2) > 1e5 cm^-3 (vs. CO n(H_2) > 1e4 cm^-3) (Solomon, vd Bout, Carilli)
ALMA 1hr
Sensitivity of future arrays: Arp 220 vs z
(FIR = 1e12 L_sun)
EVLA 100hr
Redshifts for obscured/faint sources: wide band (16 - 32 GHz) spectrometers on LMT/GBT (Min Yun 2004)
L_FIR = 1e13 L_sun
Z=10 lensed star forming galaxy? (Pello 2004)
L_app= 4e11 L_sun + LBG dust correction (5x) => L_FIR = 2e12L_sun
S_250 = 0.6 mJy => 5 ALMA detection in 1 minute!
S (CO 4-3 at 42 GHz) = 0.06 mJy => 5 EVLA detection in 15hr
Studying the pristine IGM beyond the EOR: HI 21cm observations with the Square Kilometer Array
and LOFAR
SKA: A/T = 20000 m^2/K => Jy at 200 MHz
Low frequency background – hot, confused sky
Eberg 408 MHz Image (Haslam + 1982)
Coldest regions: T = 200z)^2.6 K
Global HI signature in low frequency spectra
(Gnedin & Shaver 2003)
double
fast21cm ‘fluctuations’ at 1e-4 wrt foreground
HI 21cm Tomography of IGM Zaldarriaga + 2003
z=12 9 7.6
T_B(2’) = 10’s mK
SKA rms(100hr) = 4mK
LOFAR rms (1000hr) = 80mK
Power spectrum analysis
Zaldarriaga + 2003
PAST
LOFAR
SKA
Z=10
129 MHz
2deg 1arcmin
1422+23 z=3.62 Womble 1996
N(HI) = 1e13 -- 1e15 cm^-2, f(HI/HII) = 1e-5 -- 1e-6
=> Before reionization N(HI) =1e18 – 1e21 cm^-2
Cosmic Web after reionization = Ly alpha forest ( <= 10)
Cosmic web before reionization: HI 21cm Forest (Carilli, Gnedin, Owen 2002)
)1()10
1)((008.0 2/1
HI
S
CMB fz
T
T
• SKA ‘observations’ of 21cm absorption before the EOR (A/T = 2000 m^2/K, 240hrs, 1kHz)
• Mean optical depth (z = 10) = 1% = ‘Radio Gunn-Peterson effect’
• Narrow lines (= few %, few km/s) = HI 21cm forest (<= 10), 10/unit z at z=8
• Mini-halos (= 100) (Furlatto & Loeb 2003)
• Primordial disks: low cosmic density (0.001/unit z), but high opacity => fainter radio sources (GRBs?)
Z=10
Z=8
20mJy
Radio sources beyond the EOR?
• Radio loud QSO fraction = 10% to z=5.8 (Petric + 2003)
• Models => expect 0.05 to 0.5 deg^-2 at z> 6 with S_151 > 6 mJy (out of 100 total)
2240 at z > 6
1.4e5 at z > 6
S_151 > 6mJy
Carilli + 2002
Haiman & Hui 2004
Terrestrial interference
100 MHz 200 MHz
GMRT 230 MHz 0924-220 z=5.2
GMRT 230 MHz 0924-220 z=5.2 Continuum point source = 0.55 Jy
Noise limited spectra: =5.5 mJy/channel
HI 21cm absorption at z=5.200? = 4%, v = 130 km/s N(HI) = 9e20 (Ts/100K) cm^-2
SKA timeline
•2004 Science case: “Science with the SKA” Carilli & Rawlings, New Astron. Rev.
•2004-7 demonstrator development major external review (2006) submit funding proposals for a 5% demonstrator
•2006 site selection: Autralia, USA-SW, South Africa, China
•2008 selection of technical design (may be a combination); start construction of 5% demonstrator on chosen site
•2009 submit funding proposals for full array
•2012 start construction
•2020 complete construction
Projected cost: 1 G$
Radio astronomy – Probing the EoR
•Study physics of the first luminous sources (limited to near-IR to radio wavelengths)
•Currently limited to pathological systems (‘HLIRGs’)
•EVLA and ALMA 10-100x sensitivity is critical for study of ‘normal’ galaxies
•SKA is the only means to study the neutral IGM
z
Ultimate goal: Far side of the moon?
No RFI
No ionosphere
Cheap, ‘dirty’ antennas
No moving parts
130MHz