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History of IGM. ionized. C.Carilli (NRAO) CfA Sept 2004. neutral. Epoch of Reionization (EoR). bench-mark in cosmic structure formation indicating the first luminous structures. ionized. z=5.80. z=5.82. z=5.99. z=6.28. The Gunn Peterson Effect. - PowerPoint PPT Presentation
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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