Cosmic reionization and the history of the neutral intergalactic medium

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Cosmic reionization and the history of the
neutral intergalactic medium LANL Chris Carilli
May 23, 2007

• Current constraints on the IGM neutral fraction
  with cosmic epoch (Fan, Carilli, Keating 2006
  ARAA)
• Neutral Intergalactic Medium (IGM) HI 21cm
  telescopes, signals, and challenges
• Objects within reionization recent observations
  of molecular gas, dust, and star formation, in
  the host galaxies of the most distant QSOs, and
  more

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Ionized
Neutral
Reionized
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Chris Carilli (NRAO) Berlin June 29, 2005
WMAP structure from the big bang
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Hubble Space Telescope Realm of the Galaxies
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Dark Ages
Epoch of Reionization
Twilight Zone

• Last phase of cosmic evolution to be tested
• Bench-mark in cosmic
• structure formation
• indicating the first
• luminous structures

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Reionization the movie
Gnedin 03
8Mpc comoving
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Constraint I Gunn-Peterson Effect
z
Barkana and Loeb 2001
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Gunn-Peterson Effect
Fan et al 2006
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Gunn-Peterson limits to f(HI)
?GP 2.6e4 f(HI) (1z)3/2
End of reionization? f(HI) lt1e-4 at z
5.7 f(HI) gt1e-3 at z 6.3

• Difficulties with GP
• ? to f(HI) conversion requires clumping
  factor
• ? gtgt1 for f(HI)gt0.001 gt low f(??) diagnostic
• GP gt Reionization occurs in twilight zone,
  opaque for ?obs lt0.9 ?m

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Reionization and the CMB
Surface of last-scattering z1000
CMB angular power spectrum

• Thomson scatting during reionization (z10)
• Acoustics peaks are fuzzed-out during
  reionization.
• Problem degenerate with intrinsic amplitude of
  the anisotropies.

No reionization Reionization
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Constraint II CMB large scale polarization --
Thomson scattering during reionization
TT

• Scattered CMB quadrapole gt polarized
• Large scale horizon scale at reionization
  10s deg
• Signal is weak
• TE 10 TT (few uK)
• EE 1 TT
• EE (l 5) 0.3/- 0.1 uK

TE
EE
Page 06 Spergel 06
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Constraint II CMB large scale polarization --
Thomson scattering during reionization
TT

• ?e 0.09/-0.03
• Rules-out high ionization fraction at zgt 15
• Allows for finite (0.2) ionization to high z
• Most action occurs at z 8 to 14, with f(HI) lt
  0.5

TE
EE
Page 06 Spergel 06
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Combined CMB GP constraints on reionization

• ??????????es with CMB polarization
• ??e integral measure to recombinationgt allows
  many IGM histories
• Still a 3? result (now in EE vs. TE before)

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Pushing into reionization QSO 114852 at z6.4

• Highest redshift quasar known (tuniv 0.87Gyr)
• Lbol 1e14 Lo
• Black hole 3 x 109 Mo (Willot etal.)
• Gunn Peterson trough (Fan etal.)

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114852 z6.42 Gas detection
VLA
IRAM

• M(H2) 2e10 Mo
• zhost 6.419 /- 0.001
• (note zly? 6.37 /- 0.04)

VLA
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Constrain III Cosmic Stromgren Sphere

• Accurate zhost from CO z6.419/0.001
• Proximity effect photons leaking from
  6.32ltzlt6.419

White et al. 2003
z6.32

• time bounded Stromgren sphere R 4.7 Mpc
• tqso 1e5 R3 f(HI) 1e7yrs or
• f(HI) 1 (tqso/1e7 yr)

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Loeb Rybicki 2000
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CSS Constraints on neutral fraction at z6

• Nine z6 QSOs with CO or MgII redshifts ltRgt
  4.4 Mpc (Wyithe et al. 05 Fan et al. 06
  Kurk et al. 07)
• GP gt f(HI) gt 0.001
• If f(HI) 0.001, then lttqsogt 1e4 yrs
  implausibly short given QSO fiducial lifetimes
  (1e7 years)?
• Probability arguments size evolution suggest
  f(HI) gt 0.05

Wyithe et al. 2005
Fan et al 2005
P(gtxHI)
90 probability x(HI) gt curve
tqso/4e7 yrs
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Cosmic Stromgren Surfaces (Hui Haiman)
zhost

• Larger CSS in Ly? vs. Ly? Damping wing of
  Ly??
• Large N(HI) gt f(HI) gt 0.1

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• Difficulties for Cosmic Stromgren Spheres and
  Surfaces
• (Lidz 07, Maselli 07)
• Requires sensitive spectra in difficult near-IR
  band
• Sensitive to R f(HI) ? R-3
• Clumpy IGM gt ragged edges
• Pre-QSO reionization due to star forming
  galaxies, early AGN activity

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Cosmic phase transition?

• Not event but complex process, large variance
  time/space
• Current observations suggest zreion 6 to 14
• Good evidence for qualitative change in nature
  of IGM at z6
• Current probes are all fundamentally limited in
  diagnostic power

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Studying the pristine neutral IGM using
redshifted HI 21cm observations (100 200 MHz)

• Large scale structure
• cosmic density, ?
• neutral fraction, f(HI)
• Temp TK, TCMB, Tspin

1e13 Mo
1e9 Mo
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Multiple experiments under-way pathfinders
LOFAR (NL)
MWA (MIT/CfA/ANU)
SKA
21CMA (China)
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(No Transcript)
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Signal I Global (all sky) reionization
signature in low frequency HI spectra
Gnedin Shaver 03
140MHz
IGM heating Tspin TK gt TCMB
Ly? coupling TspinTK lt TCMB
Signal 20mK lt 1e-4 sky
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EDGES (Bowman Rogers MIT) All sky
reionization HI experiment. Single broadband
dipole experiment with (very) carefully
controlled systematics polynomial baseline
subtraction (7th order)
VaTech Dipole Ellingson
rms 75 mK
Sky gt 150 K
?Treion lt 450mK at z 6.5 to 10
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Signal II HI 21cm Tomography of IGM Zaldarriaga
2003
z12
9
7.6

• ?TB(2) 10s mK
• SKA rms(100hr) 4mK
• LOFAR rms (1000hr) 80mK

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Signal III 3D Power spectrum analysis
? only
LOFAR
? f(HI)
SKA
McQuinn 06
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Signal IV Cosmic Web after reionization Ly
alpha forest at z3.6 (? lt 10)
Womble 96
N(HI) 1e13 1e15 cm-2, f(HI/HII) 1e-5 --
1e-6 gt Before reionization N(HI) 1e18 1e21
cm-2
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Signal IV Cosmic web before reionization HI
21Forest
z12
z8
19mJy
130MHz
159MHz

• Perhaps easiest to detect (use long baselines)
• Requires radio sources expect 0.05 to 0.5
  deg-2 at zgt 6 with S151 gt 6 mJy?

• radio G-P (?1)
• 21 Forest (10)
• mini-halos (10)
• primordial disks (100)

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GMRT 230 MHz HI 21cm abs toward highest z
(5.2) radio AGN
0924-220 z5.2 S230MHz 0.5 Jy
GMRT at 230 MHz z21cm RFI 20 kiloJy !
1
8GHz Van Breugel et al.
CO Klamer
M(H2) 3e10 Mo
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GMRT 230 MHz HI 21cm abs toward highest z
radio AGN (z5.2)
232MHz 30mJy
229Mhz 0.5 Jy
rms(40km/s) 3mJy
rms(20km/s) 5 mJy
N(HI) 2e20TS cm-2 ?
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Signal V Cosmic Stromgren spheres around z gt 6
QSOs

• LOFAR observation
• 20xf(HI)mK, 15,1000km/s
• gt 0.5 x f(HI) mJy
• Pathfinders Set first hard limits on f(HI) at
  end of cosmic reionization
• Easily rule-out cold IGM (T_s lt T_cmb) signal
  360 mK

5Mpc
0.5 mJy
Wyithe et al. 2006
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Signal VI pre-reionization HI signal, eg. Baryon
Oscillations Very low frequency (lt75MHz) Long
Wavelength Array

• Very difficult to detect
• Signal 10 arcmin, 10mk gt S30MHz 0.02 mJy
• SKA sens in 1000hrs
• 20000K at 50MHz gt
• rms 0.2 mJy
• Need gt 10 SKAs
• Need DNR gt 1e6

z50
z150
Barkana Loeb 2005
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Challenge I Low frequency foreground hot,
confused sky Eberg 408 MHz Image (Haslam 1982)

• 90 Galactic foreground.
• Coldest regions T 100 (?/200 MHz)-2.6 K
• 10 Egal. radio sources 1 source/deg2 with
  S140 gt 1 Jy

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• Solution spectral decomposition (eg. Morales,
  Gnedin)
• Foreground non-thermal featureless over 100
  MHz
• Signal fine scale structure on scales few MHz

Freq
Signal/Sky 2e-5
Signal
10 FoV SKA 1000hrs
Foreground
Xcorrelation/Power spectral analysis in 3D
different symmetries in freq space
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Challenge II Ionospheric phase errors varying
e- content
TID
74MHz Lane 03

• Isoplanatic patch few deg few km
• Phase variation proportional to wavelength2

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Ionospheric phase errors The Movie
Solution Wide field rubber screen phase
self-calibration peeling
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Virgo A VLA 74 MHz Lane 02
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Challenge III Interference
100 MHz z13
200 MHz z6

• Solutions -- RFI Mitigation (Ellingson06)
• Digital filtering multi-bit sampling for high
  dynamic range (gt50dB)
• Beam nulling/Real-time reference beam
• LOCATION!

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Beam nulling -- ASTRON/Dwingeloo (van Ardenne)
Factor 300 reduction in power
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VLA-VHF 180 200 MHz Prime focus CSS search
Greenhill, Blundell (SAO) Carilli, Perley (NRAO)
Leverage existing telescopes, IF, correlator,
operations

• 110K DD/construction (CfA)
• First light Feb 16, 05
• Four element interferometry May 05
• First limits Winter 06/07

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Project abandoned Digital TV
KNMD Ch 9 150W at 100km
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RFI mitigation location, location location
100 people km-2
1 km-2
0.01 km-2
(Briggs 2005)
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Challenge IV Extreme computing

• LOFAR IBM Blue Gene/L Stella (Falcke)
• 0.5 Tbit/s input data rate
• 30 Tflop
• 12000 PCs
• Occupying 6 m2
• 150 KW power consumption

Dutch minister of science
Blue Gene
1.7 slower than 1 in Europe (Barcelona)
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Focus Reionization (power spec,CSS,abs)
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PAPER Staged Engineering Approach

• Broad band sleeve dipole gt 2x2 tile
• 8 dipole test array in GB (06/07) gt 64 station
  array in WA (07/08)
• FPGA-based pocket correlator from Berkeley
  wireless lab gt custom design.
• BEE2 5 FPGAs, 500 Gops/s
• S/W Imaging, calibration, PS analysis Miriad gt
  Python CASA, including ionospheric peeling
  calibration MFS
• Peel the problem onion

100MHz
200MHz
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PAPER First images/spectra
Cas A 1e4Jy
180MHz
140MHz
Cygnus A 1e4Jy
CygA 1e4Jy
3C348 400Jy
3C392 200Jy
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Destination Moon!

• No interference
• No ionosphere (?)
• Easy to deploy and maintain (high tolerance
  electroncs no moving parts)

10MHz
RAE2 1973
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Radio astronomy Probing Cosmic Reionization

• Twilight zone study of first light limited to
  near-IR to radio
• First constraints GP, CMBpol gt reionization is
  complex and extended
• z_reion 6 to 11
• HI 21cm most direct probe of reionization
• Low freq pathfinders
• All-sky, PS, CSS
• SKA imaging of IGM

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• European Aeronautic Defence and Space
  Corporation/ASTRON (Falcke)
• Payload 1000 kg (Ariane V)
• 100 antennas at 1-10 MHz 1/10 SKA

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END
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Very low frequencies (lt10MHz) Lunar challenges

• IPS/ISS angular/temporal broadening 1MHz gt
  1deg, 5years
• Faraday rotation gt no linear polarization
• High sky temperature
• Low power super computing LOFAR/Blue Gene
  0.15MW
• Lunar ionosphere np 0.2 to 1MHz (LUNA19,20
  1970s)?
• Diffraction limits how sharp is knifes edge?

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Good news The Moon is radio protected!

• The back side of the moon is declared as a radio
  protected site within the ITU Radio Regulations
• The IT Radio Regulations are an international
  treaty within the UN.
• Details are specified in a published ITU
  Recommendation (this is a non-mandatory
  recommendation, but is typically adhered to).
• Radio astronomy on the moon has been a
  long-standing goal, protected by international
  treaties!
• Steps need to be taken to protect the pristine
  and clean nature of the moon.
• Lunar communication on the far side needs to be
  radio quiet.

• ARTICLE 22
• (ITU Radio Regulations)
• Space services
• Section V Radio astronomy in the shielded
  zone of the Moon
• 22.22 8 1) In the shielded zone of the Moon31
  emissions causing harmful interference to radio
  astronomy observations32 and to other users of
  passive services shall be prohibited in the
  entire frequency spectrum except in the following
  bands
• 22.23 a) the frequency bands allocated to the
  space research service using active sensors
• 22.24 b) the frequency bands allocated to the
  space operation service, the Earth
  exploration-satellite service using active
  sensors, and the radiolocation service using
  stations on spaceborne platforms, which are
  required for the support of space research, as
  well as for radiocommunications and space
  research transmissions within the lunar shielded
  zone.
• 22.25 2) In frequency bands in which emissions
  are not prohibited by Nos. 22.22 to 22.24, radio
  astronomy observations and passive space research
  in the shielded zone of the Moon may be protected
  from harmful interference by agreement between
  administrations concerned.
• 22.22.1 The shielded zone of the Moon comprises
  the area of the Moons surface and an adjacent
  volume of space which are shielded from emissions
  originating within a distance of 100 000 km from
  the centre of the Earth.
• 32 22.22.2 The level of harmful interference is
  determined by agreement between the
  administrations concerned, with the guidance of
  the relevant ITU-R Recommendations.

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Sources responsible for reionization

• Luminous AGN No
• Star forming galaxies maybe -- dwarf galaxies
  (Bowens05 Yan04)?
• mini-QSOs -- unlikely (soft Xray BG Dijkstra04)
• Decaying sterile neutrinos -- unlikely (various
  BGs Mapelli05)
• Pop III stars zgt10? midIR BG (Kashlinsky05),
  but trecomb lt tuniv at z10
• GP gt Reionization occurs in twilight zone,
  opaque for ?obs lt0.9 ?m

Needed for reion.
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Radio galaxy spectra Smooth powerlaw (eg. Cygnus
A)
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Tsiolkovsky crater
Tsiolkovsky crater (100 km diameter) 20S 129E
Apollo 15