History of IGM

• bench-mark in cosmic structure formation indicating the first luminous structures

Epoch of Reionization (EoR)

C.Carilli (NRAO) CfA Sept 2004

ionized

neutral

ionized

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’ at z=6 to 7

Log (HI fraction)

Density Gas Temp

Ionizing intensity

Normalization: GP absorption, LCDM + z=4 LBGs, T_IGM

8 Mpc (comoving)

Thompson scattering at EoR

e = 0.17 => F(HI) < 0.5 at z=17

Extended period of reionization: z=6 to 15?

WMAP Large scale polarization of CMB (Kogut et al.)

20deg

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)

Complex reionization example: Double reionization? (Cen 2002)

Pop III stars in ‘mini-halos’ (<1e7 M_sun)

‘normal’ galaxies (>1e8M_sun)

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 to optical observers

Radio astronomical probes of the Epoch of Reionization and the 1st luminous objects

1. CMB large scale polarization

2. Objects within EoR – Molecular gas, dust, star formation

3. Neutral IGM – HI 21cm emission and absorption

Collaborators

USA – Carilli, Walter, Fan, Strauss, Owen, Gnedin

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.aoc.nrao.edu/~ccarilli/CHAPS.shtml

IRAM 30m + MAMBO: sub-mJy sens at 250 GHz + wide fields

IRAM PdBI: sub-mJy sens at 90 and 230 GHz + arcsec resol.

VLA: uJy sens at 1.4 GHz

VLA: < 0.1 mJy sens at 20-50 GHz + 0.2” resol.

Magic of (sub)mm

L_FIR = 4e12 x S_250(mJy) L_sun for z=0.5 to 8

SDSS + DPOSS:

700 at z > 4

30 at z > 5

9 at z > 6

M_B < -26 =>

L_bol > 1e14 L_sun

M_BH > 1e9 M_sun

York et al 2001; Fan et al

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

1e3 M_sun/yr

High-z sources

•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

Typical of starburst nucleus

VLA imaging of CO3-2 at 0.4” 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

Phase stability: Fast switching at the VLA

10km baseline rms = 10deg

1148+5251: radio-FIR SED

Star forming galaxy characteristics: radio-FIR SED, L’_CO/FIR, CO excitation and T_B => Coeval starburst/AGN: SFR = 1000 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?

1148+52: Masses

Cosmic (proper) time

T_univ = 0.87Gyr

• 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+/0.001Ly a, high ioniz. Lines: uncertainty >1000km/s (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

Richards et al. 2002SDSS QSOs

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 given fiducial lifetime, f_lt = 1e7 years?

Probability arguments suggest: f(HI) > 0.1 at z=6.4 – much better limit than GP

Wyithe and Loeb 2003

z>6 QSOs with MgII and/or CO redshifts (Walter et al, Willot et al., Maiolino et al.,

<z> = 0.08 => <R> = 4.4 Mpc

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)

Gas and dust during the EoR

• FIR luminous galaxy at z=6.42: 1e13 Lsun observe dust, gas, star formation, AGN

• Merging(?) galaxy: Molecular gas mass = 2x1010 M_sun, M_dyn = 6e10 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

S_250 = 3.0 +/- 0.4 mJy => L_FIR = 7.5e12 L_sun

z(MgII)

S(CO 3-2) = 0.17 +/- 0.09 mJy

EVLA correlator: 8GHz, 16000 channels

z(opt)

MAMBO 250 GHz VLA CO 3-2

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

z=4.7

z=6.4

70 uJy

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

ConX: 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

Terrestrial interference

100 MHz z=13

200 MHz z=6

Temperatures: Spin, CMB, Kinetic and the 21cm signal

•Initially T_S= T_CMB

•T_S couples to T_K via Lya scattering

•T_K = 0.026 (1+z)^2 (wo. heating)

•T_CMB = 2.73 (1+z)

•T_S = T_CMB => no signal

•T_S = T_K < T_CMB => Absorption against CMB

•T_S > T_CMB => Emission

T_K

T_CMBT_s

Tozzi + 2002

z = 11 z = 7

t = 10mK

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

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

• 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) (Furlanetto & Loeb 2003)

• Primordial disks: low cosmic density=0.001/unit z, but high opacity=> fainter radio sources -- GRBs?

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 (Carlli,Jarvis,Haiman)

Z=1020mJy

Z=8

GMRT 228 MHz search for HI21cm abs toward highest z radio galaxy, 0924-220 z=5.2

Continuum point source = 0.55 Jy; rms/(40km/s chan) = 5 mJy

z(CO)230Mhz

8GHz

1”

Van Breugel et al.

GMRT 230 MHz 0924-220 z=5.2

channel 20 (229.60MHz)

‘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 et al – proposed)

Leverage: existing telescopes, IF, correlator, operations

Main Experiment: Cosmic Stromgren spheres around z>6 SDSS QSOs (Wyithe & Loeb 2004)

VLA spectral/spatial resolution well matched to expected signal: 5’, 1000 km/s

VLA-VHF 190MHz 250hrs

15’

20mK

0.50+/-0.12 mJy

Other Experiments: power spectrum analysis, ‘HI 21cm forest’

Sensitivity per 0.8MHz channel: currently have 16 channels over 12.5 MHz

Piggy-back on CSS experiment

Centrally condensed uv coverage

System/Site characteristics

Work hours

TV carrier

Proposed band

First sidelobe = 15db

Challenges and ‘mitigation’: VLA-VHF CSS Ionospheric phase errors – higher freq (freq^-2); 4deg FoV; 1km B_max

T_bg – higher freq (freq^-2.75)

Confusion (in-beam) – spectral measurement (eg. Morales & Hewitt 2004); mJy point source removal w. A array; precise position and redshift

Wide field problems – polarization, sidelobes, bandpass – all chromatic ?

RFI – “interferometric excision” (but D array); consistently ‘clean’ times in

monitor plots (but very insensitive measure) ?

Proposed Cost and Timeline

100K in parts (CfA) + labor (CfA/NRAO)

First tests (4 prototypes): Q1, Q2 2005

First experiments (100-200 hr): D array, Q4 2005

Large proposal (500 hr): D array, Q1 2007

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, ALMA 10-100x sensitivity is critical to study normal galaxies

•Low freq pathfinders: HI 21cm signatures of neutral IGM

•SKA imaging of IGM

z