History of IGM
•last phase of cosmic evolution to be tested
•bench-mark in cosmic structure formation indicating the first luminous structures
Epoch of Reionization (EoR)
C.Carilli (NRAO) Heidelberg 05
F(HI) = 0
F(HI) = 1
F(HI) = 1e-5
z=5.80
z=5.82
z=5.99
z=6.28
The Gunn Peterson Effect
Fan et al 2003
End of reionization f(HI) > 0.001 at z = 6.3
=> opaque at _obs<0.9m
Fan + 2005; White + 2005
Near-edge of reionization: GP Effect
Fairly Fast:• f(HI) > 1e-3 at z >= 6.3 (0.87Gyr)
• f(HI) < 1e-4 at z <= 5.7 (1.0 Gyr)
Although cf. Songaila, Oh, Stern, Malhotra…
Neutral IGM evolution (Gnedin 2004): ‘Cosmic Phase transition’ at z=6 to 7
Normalization: GP absorption, LCDM + z=4 LBGs, T_IGM
8 Mpc (comoving)
CMB Temperature fluctuations imprinted by primordial density fluctuations at last scattering (z=1000)
Large scale polarization: Thompson scattering at EoR
e = 0.17 =>
F(HI) < 0.5 at z=17
WMAP Large scale polarization of CMB (Kogut et al.)
20deg
GP + CMB => ‘complex’ reionization extending from z=20 to 6?
Limitations of current measurements:
CMB polarization: -- _e = Ln_ee = integral measure through universe=> allows many reionization scenarios
Gunn-Peterson effect: -- _Lya >>1 for f(HI)>0.001-- High z universe is opaque at (observed) optical wavelengths
Reionization occurs in ‘twilight zone’, observable at near-IR through radio wavelengths
Radio astronomical probes of the Epoch of Reionization and the 1st luminous objects
1. CMB: large scale polarization + secondary anisotropies
2. Objects within EoR – Molecular gas, dust, star formation, process of reionization
3. Neutral IGM – HI 21cm emission and absorption
Collaborators
USA – Carilli, Walter, Fan, Strauss, Owen, Gnedin, Lo
Euro – Bertoldi, Cox, Menten, Omont, Beelen
SKA Key Program science team– Briggs, Carilli, Furlanetto, Rawlings
Science with the Square Kilometer Array (NAR, Carilli & Rawlings) http://www.skatelescope.org/pages/page_astronom.htm
IRAM 30m + MAMBO: sub-mJy sens at 250 GHz + wide fields dust
IRAM PdBI: sub-mJy sens at 90 and 230 GHz + arcsec resol. mol. gas
VLA: uJy sens at 1.4 GHz star formation
VLA: < 0.1 mJy sens at 20-50 GHz + 0.2” resol. mol. gas (low order)
Magic of (sub)mm: distance independent method of studying objects in universe for z=0.8 to 8
L_FIR = 4e12 x S_250(mJy) L_sun
SFR = 1e3 x S_250 M_sun/yrRadio-FIR (Yun+ 02)
FIR = 1.6e12 L_sun
• z>4: 950 known • z>5: 52 • z>6: 8• 30 at z~6 expected in
the whole survey
M_B < -26 =>
L_bol > 1e14 L_sun
M_BH > 1e9 M_sun
High Redshift QSOs: SDSS, DPSS (Fan 2005)
QSO host galaxies – M_BH – relation
• Most (all?) low z spheroidal galaxies have SMBH: M_BH=0.002M_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
1e3 M_sun/yr
High-z sources
VLA detections of HCN 1-0 emission
n(H_2) > 1e5 cm^-3 (vs. CO: n(H_2) > 1e3 cm^-3)
z=2.58
Solomon et al
index=1
70 uJy
•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
Cosmic (proper) time
T_univ = 0.87Gyr
1148+52 z=6.42: Dust and Gas detection
Off channelsRms=60uJy
46.6149 GHzCO 3-2
• Dust formation: 1.4e9yr (AGB winds) > t_univ (8.7e8yr) => dust formed in high mass stars? => silicate grains?
• C, O production (3e7 M_sun): few e8 yr => Star formation started early (z = 10)?
L_FIR = 1.2e13 L_sun, M_dust =7e8M_sunM(H_2) = 2e10 M_sun
S_250 = 5.0 +/- 0.6 mJy
IRAM Plateau de Bure
• FWHM = 305 km/s• z = 6.419 +/- 0.001
(3-2)
(7-6)
(6-5)
• Tkin=100K, nH2=105cm-3
Typical of starburst nuclei (eg. NGC253, Arp220)
VLA imaging of CO3-2 at 0.4” and 0.15” resolution
Separation = 0.3” = 1.7 kpc
T_B = 20K Typical of starburst nuclei
Merging galaxies?
rms=50uJy at 47GHz
CO extended to NW by 1” (=5.5 kpc) tidal(?) feature
1148+5251: radio-FIR SED
Star forming galaxy characteristics: radio-FIR SED, Gas/Dust, CO excitation and T_B => Coeval starburst/AGN? SFR = 1e3 M_sun/yr
Stellar spheroid formation in few e7 yrs = e-folding time for SMBH
=> Coeval formation of galaxy/SMBH at z = 6.4 ?
S_1.4= 55 +/- 12 uJy
1048+46
Beelen et al.
T_D = 50 K
•M(dust) = 7e8 M_sun
•M(H_2) = 2e10 M_sun
•M_dyn (r=2.5kpc) = 5e10 M_sun
•M_BH = 3e9 M_sun => 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? [SMBH forms first?]
1148+52: Masses
Cosmic Stromgren Sphere
• Accurate redshift from CO: z=6.419+/0.001Ly a, high ioniz Lines: inaccurate redshifts (z > 0.03)
• Proximity effect: photons leaking from 6.32<z<6.419
z=6.32
•‘time bounded’ Stromgren sphere: R = 4.7 Mpc
t_qso= 1e5 R^3 f(HI)= 1e7yrs
White et al. 2003
Loeb & Rybicki 2000
z>6 QSOs with MgII and/or CO redshifts (Wyithe et al. 05)
<z> = 0.08 => <R> = 4.4 Mpc
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 given QSO fiducial lifetimes (1e7 years)?
Probability arguments suggest: f(HI) > 0.1
Wyithe et al. 2005
t_qso/1e7 yrs
90% probability x(HI) > curve
P(>x_HI)
10%
Near-edge of reionization: GP + Cosmic Stromgren Spheres
Very Fast?• f(HI) > 1e-1 at z > 6.4 (0.87Gyr)
• f(HI) < 1e-4 at z < 5.7 (1.0 Gyr)
See also Cosmic Stromgren Surfaces (Mesinger & Haiman 2004 but cf. Oh & Furnaletto 2005)
Molecular Gas and dust during the EoR
• FIR luminous galaxy at z=6.42: 1e13 Lsun observe dust, gas, star formation, AGN
• Sub-kpc imaging: Merging galaxy: M_gas= 2x1010 M_sun, M_dyn=6e10 M_sun
• Early enrichment of heavy elements and dust produced => star formation 0.4 Gyr after the big bang
• High z: Coeval formation of SMBH + stars and break-down of M- at high z?
• Cosmic Stromgren sphere = 4.7 Mpc => ‘witnessing process of reionization’ t_qso = 1e7 * f(HI) yrs ‘fast’ reionization: f(HI)>0.1 at z=6.4?
Continuum sensitivity of future arrays: Arp 220 vs z (FIR = 1.6e12 L_sun)
cm: Star formation, AGN
(sub)mm: Dust, molecular gas
Near-IR: Stars, ionized gas, AGN
Studying the pristine IGM beyond the EOR: redshifted HI
21cm observations (100 – 200 MHz) with the Square Kilometer Array. ‘Pathfinders’: LOFAR, MWA, PAST, VLA-VHF,…
SKA goal: Jy at 200 MHz Large scale structure: density, f(HI), T_spin
Low frequency background – hot, confused sky
Eberg 408 MHz Image (Haslam + 1982)
Coldest regions: T = 100z)^-2.6 K
Highly ‘confused’: 3 sources/arcmin^2 with S_0.2 > 0.1 mJy
Interference
100 MHz z=13
200 MHz z=6
Ionospheric phase errors
TIDs – ‘fuzz-out’ sources
‘Isoplanatic patch’ = few deg = few km
Phase variation proportional to wavelength^2
74MHz Lane 03
Global reionization signature in low frequency HI spectra
(Gnedin & Shaver 2003)
double
fast21cm ‘deviations’ at
1e-4 wrt foreground
Spectral index deviations of 0.001
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
LOFAR
SKA
Z=10
129 MHz
2deg 1arcmin
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) 1422+23 z=3.62 Womble 1996
• radio G-P (=1%)
• 21 Forest (10%)
• mini-halos (10%)
• primordial disks (100%)
• expect 0.05 to 0.5 deg^-2 at z> 6 with S_151 > 6 mJy (Carlli,Jarvis,Haiman)
z=12 z=8
Cosmic web before reionization: HI 21Forest
20mJy
130MHz
‘Pathfinders’: PAST, LOFAR, MWA, VLA-VHF, …
MWA prototype (MIT/ANU)
LOFAR (NL)
PAST (CMU/China) VLA-VHF (CfA/NRAO)
VLA-VHF: 180 – 200 MHz Prime focus X-dipole Greenhill, Blundell (SAO Rx lab); Carilli, Perley (NRAO)
Leverage: existing telescopes, IF, correlator, operations
$110K D+D/construction (CfA)
First light: Feb 16, 05
Four element interferometry: May 05
First limits: Dec 05
Main Experiment: Cosmic Stromgren spheres around z=6 to 6.5 SDSS QSOs (Wyithe & Loeb 2004)
VLA-VHF 190MHz 250hrs
15’
20 f(HI) mK
0.50+/-0.12 mJy
VLA spectral/spatial resolution well matched to expected signal: 7’, 1000 km/s
Set first hard limits on f(HI) at end of cosmic reionization (f(HI) < 0.3)
Easily rule-out cold IGM (T_s < T_cmb): signal = 360 mK
Other Experiments: power spectrum analysis, ‘HI 21cm forest’
2deg
First sidelobe = 14% (goal < 5%)
Efficiency = 28% (goal: 50%)
Xpol = 20% (goal: 5%)
T_sys = 50 (Rx) + 150 (sky) K
FoV = 12 deg^2
rms/chan= 0.12mJy in 250 hrs (goal)
Correlator: 0.8MHz/chan, 16 chan, 2 pol.
System characteristics
4deg
3C313 --first image
Main hurdle: Interference!
Digital TV: 186 to 192MHz, 200 W from ABQ
KNMD Ch 9 Digital TV
Radio astronomy – Probing the EoR
•‘Twilight zone’:physics of 1st luminous sources (limited to near-IR to radio wavelengths)
•Currently limited to pathological systems (‘HLIRGs’)
•EVLA, ALMA 10-100x sensitivity is critical to study normal galaxies
•Low freq pathfinders: HI 21cm signatures of neutral IGM
•SKA imaging of IGM
z
PKS 2322+1944 z=4.12: [CI] (492 GHz rest freq; Pety et al.)
=> Solar Metalicity
PdBI
VLA CO2-1
GMRT 228 MHz – HI 21cm abs toward highest z radio galaxy, 0924-220 z=5.2
rms/(40km/s chan) = 5 mJy
z(CO)
230Mhz
point source = 0.55 Jy;
8GHz
1”
Van Breugel et al.
RFI = 20 kiloJy !
Richards et al. 2002SDSS QSOs1000km/s => z = 0.03
J1048+4637: A second FIR-luminous QSO source at z=6.2
S_250 = 3.0 +/- 0.4 mJy=> L_FIR=7.5e12 L_sun
z(MgII)GBT/EVLA/ALMA/LMT correlator: 8–32 GHz, 16000 channels
z(opt)
VLA CO(3-2)
Gunn-Peterson effect
Barkana and Loeb 2001
Complex reionization example: Double reionization? (Cen 2002; cf. Furlanetto, Gnedin,…)
Pop III stars in ‘mini-halos’ (<1e7 M_sun)
‘normal’ galaxies (>1e8M_sun)
Recombination time < hubble time at z > 8
Stellar fusion produces 7e6eV/H atom, reionization requires 13.6eV/H atom =>Need to process only 1e-5 of baryons through stars to reionize the universe
