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Observing the First Galaxies and the Reionization Epoch. Steve Furlanetto UCLA February 5, 2008. Outline. Introduction: Observing Reionization Galaxy Surveys Current observations of LAEs The Clustering Signature The 21 cm Transition as a Cosmological Probe Basic Physics - PowerPoint PPT Presentation
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Observing the First Galaxiesand the Reionization EpochObserving the First Galaxiesand the Reionization Epoch
Steve Furlanetto
UCLA
February 5, 2008
Steve Furlanetto
UCLA
February 5, 2008
OutlineOutline
Introduction: Observing Reionization Galaxy Surveys
Current observations of LAEs The Clustering Signature
The 21 cm Transition as a Cosmological Probe Basic Physics The Mean 21 cm Background Measurements and Challenges The Pre-reionization IGM Reionization
Conclusion
Introduction: Observing Reionization Galaxy Surveys
Current observations of LAEs The Clustering Signature
The 21 cm Transition as a Cosmological Probe Basic Physics The Mean 21 cm Background Measurements and Challenges The Pre-reionization IGM Reionization
Conclusion
A Brief History of the UniverseA Brief History of the Universe
Last scattering: z=1089, t=379,000 yr
Today: z=0, t=13.7 Gyr
Reionization: z=6-20, t=0.2-1 Gyr
First galaxies: ?
Last scattering: z=1089, t=379,000 yr
Today: z=0, t=13.7 Gyr
Reionization: z=6-20, t=0.2-1 Gyr
First galaxies: ?
Big Bang
Last ScatteringDark Ages
Galaxies, Clusters, etc.
Reionization
G. Djorgovski
First Galaxies
ReionizationReionization
First stars and galaxies produce ionizing photons
Ionized bubbles grow and merge
Affects all baryons in the universe
Phase transition
First stars and galaxies produce ionizing photons
Ionized bubbles grow and merge
Affects all baryons in the universe
Phase transition
Mesinger & FurlanettoMesinger & Furlanetto
ReionizationReionization
Mesinger & FurlanettoMesinger & Furlanetto
First stars and galaxies produce ionizing photons
Ionized bubbles grow and merge
Affects all baryons in the universe
Phase transition
First stars and galaxies produce ionizing photons
Ionized bubbles grow and merge
Affects all baryons in the universe
Phase transition
ReionizationReionization
Mesinger & FurlanettoMesinger & Furlanetto
First stars and galaxies produce ionizing photons
Ionized bubbles grow and merge
Affects all baryons in the universe
Phase transition
First stars and galaxies produce ionizing photons
Ionized bubbles grow and merge
Affects all baryons in the universe
Phase transition
ReionizationReionization
Mesinger & FurlanettoMesinger & Furlanetto
First stars and galaxies produce ionizing photons
Ionized bubbles grow and merge
Affects all baryons in the universe
Phase transition
First stars and galaxies produce ionizing photons
Ionized bubbles grow and merge
Affects all baryons in the universe
Phase transition
Reionization:Observational Constraints
Reionization:Observational Constraints
Quasars/GRBs CMB optical depth Ly-selected galaxies
Quasars/GRBs CMB optical depth Ly-selected galaxies
Furlanetto, Oh, & Briggs (2006)
Ly Emitters and HII RegionsLy Emitters and HII Regions
Total optical depth in Ly transition:
Damping wings are strong
Total optical depth in Ly transition:
Damping wings are strong
IGM HI
€
τGP ≈ 3x105 xHI
1+ z
7
⎛
⎝ ⎜
⎞
⎠ ⎟3 / 2
LAEs During ReionizationLAEs During Reionization
z=9, R=125 observation, with M>1.7x1010 Msun Galaxies in small bubbles (underdense regions) masked
out by absorption
z=9, R=125 observation, with M>1.7x1010 Msun Galaxies in small bubbles (underdense regions) masked
out by absorption
xH=0 xH=0.26 xH=0.51 xH=0.77
Mesinger & Furlanetto (2007)Mesinger & Furlanetto (2007)
A Declining Number Density?A Declining Number Density?
Largest survey to date with Subaru
Apparent decline at bright end
Disputed by Dawson et al. (2007)
Largest survey to date with Subaru
Apparent decline at bright end
Disputed by Dawson et al. (2007)
Kashikawa et al. (2006)
A Declining Number Density?A Declining Number Density?
Similar behavior to z=7 One (!) detection L>1043 erg/s
detection threshold
Similar behavior to z=7 One (!) detection L>1043 erg/s
detection threshold
Iye et al. (2006)
An Increasing Number Density?An Increasing Number Density?
Stark et al. (2007) found 6 candidate LAEs behind massive clusters Search along lensing caustics z=9-10 L~1041-1042 erg/s Most obvious interlopers ruled
out
Stark et al. (2007) found 6 candidate LAEs behind massive clusters Search along lensing caustics z=9-10 L~1041-1042 erg/s Most obvious interlopers ruled
out
Kashikawa et al. (2006)
Stark et al. (2007), z=9
An Increasing Number Density?An Increasing Number Density?
Solid curves show mass functions with absorption
Four scenarios for luminosities (right to left): Same as z=6 LAEs Same as z=6 LAEs, but Pop III All baryons form Pop II stars,
simultaneously All baryons form Pop III stars,
simultaneously
Reasonable scenarios require fully ionized!
Solid curves show mass functions with absorption
Four scenarios for luminosities (right to left): Same as z=6 LAEs Same as z=6 LAEs, but Pop III All baryons form Pop II stars,
simultaneously All baryons form Pop III stars,
simultaneously
Reasonable scenarios require fully ionized!
Mesinger & Furlanetto (2008)
LAE ClusteringDuring Reionization
LAE ClusteringDuring Reionization
Nearly randomly distributed galaxy population
Small bubble: too much extinction, disappears
Large bubble: galaxies visible to survey
Nearly randomly distributed galaxy population
Small bubble: too much extinction, disappears
Large bubble: galaxies visible to survey
LAE ClusteringDuring Reionization
LAE ClusteringDuring Reionization
Small bubble: too much extinction, disappears
Large bubble: galaxies visible to survey
Absorption selects large bubbles, which tend to surround clumps of galaxies
Small bubble: too much extinction, disappears
Large bubble: galaxies visible to survey
Absorption selects large bubbles, which tend to surround clumps of galaxies
LAE ClusteringDuring Reionization
LAE ClusteringDuring Reionization
Small bubble: too much extinction, disappears
Large bubble: galaxies visible to survey
Absorption selects large bubbles, which tend to surround clumps of galaxies
Small bubble: too much extinction, disappears
Large bubble: galaxies visible to survey
Absorption selects large bubbles, which tend to surround clumps of galaxies
Enhanced Clustering During Reionization
Enhanced Clustering During Reionization
Shows enhanced probability to have N>1 galaxies in an occupied cell
Measuring requires deep survey over ~106-107 Mpc3
Shows enhanced probability to have N>1 galaxies in an occupied cell
Measuring requires deep survey over ~106-107 Mpc3
Mesinger & Furlanetto (2008)
The Future of LAE SurveysThe Future of LAE Surveys
Advantages: Familiar strategies Study galaxies as
well
Advantages: Familiar strategies Study galaxies as
well
Disadvantages: Uncertainties about
galaxy formation Need large volume,
deep surveys Indirect information
about IGM
Disadvantages: Uncertainties about
galaxy formation Need large volume,
deep surveys Indirect information
about IGM
The Spin-Flip TransitionThe Spin-Flip Transition
Proton and electron both have spin magnetic fields
Produces 21 cm radiation (=1420 MHz)
Extremely weak transition Mean lifetime ~107 yr Optical depth ~1% in fully
neutral IGM
Proton and electron both have spin magnetic fields
Produces 21 cm radiation (=1420 MHz)
Extremely weak transition Mean lifetime ~107 yr Optical depth ~1% in fully
neutral IGM
The 21 cm TransitionThe 21 cm Transition
Map emission (or absorption) from IGM gas Requires no background
sources Spectral line: measure
entire history Direct measurement of
IGM properties No saturation!
Map emission (or absorption) from IGM gas Requires no background
sources Spectral line: measure
entire history Direct measurement of
IGM properties No saturation!
SF, AS, LH (2004)
€
δTb ≈ 23xHI (1+ δ) 1+ z
10
⎛
⎝ ⎜
⎞
⎠ ⎟
1/ 2 TS −TbkgdTS
⎛
⎝ ⎜
⎞
⎠ ⎟H(z) /(1+ z)
∂vr /∂r
⎛
⎝ ⎜
⎞
⎠ ⎟ mK
€
δTb ≈ 23xHI (1+ δ) 1+ z
10
⎛
⎝ ⎜
⎞
⎠ ⎟
1/ 2 TS −TbkgdTS
⎛
⎝ ⎜
⎞
⎠ ⎟H(z) /(1+ z)
∂vr /∂r
⎛
⎝ ⎜
⎞
⎠ ⎟ mK
The Spin TemperatureThe Spin Temperature
CMB photons drive toward invisibility: TS=TCMB
Collisions couple TS to TK Dominated by electron exchange in H-H
collisions in neutral medium (Zygelman 2005) Dominated by H-e- collisions in partially
ionized medium (Furlanetto & Furlanetto 2006), with some contribution from H-p collisions (Furlanetto & Furlanetto 2007)
CMB photons drive toward invisibility: TS=TCMB
Collisions couple TS to TK Dominated by electron exchange in H-H
collisions in neutral medium (Zygelman 2005) Dominated by H-e- collisions in partially
ionized medium (Furlanetto & Furlanetto 2006), with some contribution from H-p collisions (Furlanetto & Furlanetto 2007)
The Global Signal:The Dark Ages
The Global Signal:The Dark Ages
Straightforward physics Expanding gas Recombination Compton scattering
Straightforward physics Expanding gas Recombination Compton scattering
SF, PO, FB (2006)
The Wouthuysen-Field Mechanism I
The Wouthuysen-Field Mechanism I
0S1/2
1S1/2
0P1/2
1P1/2
1P3/2
2P3/2
Selection Rules: F=0,1 (except F=0 F=0)
Mechanism is effective with ~0.1 Ly photon/baryon
The Wouthuysen-FieldMechanism II
The Wouthuysen-FieldMechanism II
Relevant photons are continuum photons that redshift into the Ly resonance
Relevant photons are continuum photons that redshift into the Ly resonance
Ly
…
LyδLyLy
The Global Signal:First Light
The Global Signal:First Light
First stars (quasars?) flood Universe with photons W-F effect Trigger absorption in
cold IGM
First stars (quasars?) flood Universe with photons W-F effect Trigger absorption in
cold IGM
Pop II Stars
SF (2006)
feedback
Pop III Stars
The First Sources of Light:X-ray Heating
The First Sources of Light:X-ray Heating
X-rays are highly penetrating in IGM Mean free path >Mpc Deposit energy as heat,
ionization Produced by…
Supernovae Stellar mass black holes Quasars Very massive stars
X-rays are highly penetrating in IGM Mean free path >Mpc Deposit energy as heat,
ionization Produced by…
Supernovae Stellar mass black holes Quasars Very massive stars
The Global Signal:First Light
The Global Signal:First Light
First stars (quasars?) flood Universe with photons W-F effect Heating Ionization Timing depends on f*,
fesc, fX, stellar population
First stars (quasars?) flood Universe with photons W-F effect Heating Ionization Timing depends on f*,
fesc, fX, stellar population
Pop II Stars
SF (2006)
feedback
Pop III Stars
21 cm Observations21 cm Observations
Experiments Global Signal: CoRE-
ATNF, EDGES Fluctuations: 21CMA,
LOFAR, MWA, GMRT, PAPER, SKA
Imaging: SKA
Experiments Global Signal: CoRE-
ATNF, EDGES Fluctuations: 21CMA,
LOFAR, MWA, GMRT, PAPER, SKA
Imaging: SKA
MWAMWA
Terrestrial InterferenceTerrestrial Interference
Mileura spectrum, 15 sec integrations Two types:
Fixed site (low frequency filling factor) Aircraft/meteor trail reflections (low duty cycle)
Basic strategy: excise contaminated channels
Mileura spectrum, 15 sec integrations Two types:
Fixed site (low frequency filling factor) Aircraft/meteor trail reflections (low duty cycle)
Basic strategy: excise contaminated channels
BowmanBowman
et al. (2007)et al. (2007)
Ionospheric DistortionsIonospheric Distortions
Refraction in ionosphere distorts wavefronts
Analog of optical seeing layer
Solved on software level with calibration sources
Challenge: wide-field imaging
Refraction in ionosphere distorts wavefronts
Analog of optical seeing layer
Solved on software level with calibration sources
Challenge: wide-field imaging
W. CottonW. Cotton
Astronomical ForegroundsAstronomical Foregrounds
Landecker et al. (1969)Landecker et al. (1969) Map at 150 MHz
Contours are in Kelvin
The Synchrotron ForegroundsThe Synchrotron Foregrounds
A single synchrotron electron produces a broad but smooth spectrum
A single synchrotron electron produces a broad but smooth spectrum
FrequencyFrequency
IntensityIntensity
B
e- path
The Synchrotron ForegroundsThe Synchrotron Foregrounds
A single synchrotron electron produces a broad but smooth spectrum
Electron velocity scales the spectrum
A single synchrotron electron produces a broad but smooth spectrum
Electron velocity scales the spectrum
FrequencyFrequency
IntensityIntensity
The Synchrotron ForegroundsThe Synchrotron Foregrounds
Synchrotron spectrum mirrors distribution of fast electrons
Typically near power-law, with ~K/MHz gradient
Synchrotron spectrum mirrors distribution of fast electrons
Typically near power-law, with ~K/MHz gradient
FrequencyFrequency
IntensityIntensity
Measuring the Global Signal?Measuring the Global Signal?
Signal gradient is few mK/MHz
Foregrounds vary as (near) power law Synchrotron, free-free Gradient is few K/MHz
CoRE-ATNF, EDGES experiments are trying Distinctive shape may help
Signal gradient is few mK/MHz
Foregrounds vary as (near) power law Synchrotron, free-free Gradient is few K/MHz
CoRE-ATNF, EDGES experiments are trying Distinctive shape may help
SF (2006)
Foregrounds on Small ScalesForegrounds on Small Scales
0.5 MHz
Foreground RemovalForeground Removal
Removal algorithms fairly well-developed Zaldarriaga et al. (2004), Morales & Hewitt (2004), Santos et al. (2005), McQuinn et al. (2007)
Removal algorithms fairly well-developed Zaldarriaga et al. (2004), Morales & Hewitt (2004), Santos et al. (2005), McQuinn et al. (2007)
Frequency
Tb
Cleaned Signal ~ 10 mK
Total Signal ~ 400 K
Foreground NoiseForeground Noise
Thermal noise is NOT smooth: varies between each channel
For first generation instruments, 1000 hr observations still have S/N<1 per pixel
Imaging is not possible until SKA!
Thermal noise is NOT smooth: varies between each channel
For first generation instruments, 1000 hr observations still have S/N<1 per pixel
Imaging is not possible until SKA!
The Murchison Widefield ArrayThe Murchison Widefield Array
Low Frequency Demonstrator under construction (fully funded, first light ~2008)
Located on sheep ranch in Western Australia
Low Frequency Demonstrator under construction (fully funded, first light ~2008)
Located on sheep ranch in Western AustraliaBowman et al. (2007)Bowman et al. (2007)
The Murchison Widefield ArrayThe Murchison Widefield Array
Bowtie antennae grouped in tiles of 16 Broad frequency response Large field of view
Bowtie antennae grouped in tiles of 16 Broad frequency response Large field of view
Bowman et al. (2007)Bowman et al. (2007)
Murchison Widefield Array:Low Frequency Demonstrator
Murchison Widefield Array:Low Frequency Demonstrator
Instrument characteristics Radio-quiet site 500 16-element antennae in
1.5 km distribution 7000 m2 total collecting area Full cross-correlation of all 500
antennae 80-300 MHz 32 MHz instantaneous
bandwidth at 8 kHz resolution 20-30 degree field of view
Instrument characteristics Radio-quiet site 500 16-element antennae in
1.5 km distribution 7000 m2 total collecting area Full cross-correlation of all 500
antennae 80-300 MHz 32 MHz instantaneous
bandwidth at 8 kHz resolution 20-30 degree field of view Bowman et al. (2007)Bowman et al. (2007)
Error Estimates: z=8Error Estimates: z=8
Survey parameters z=8 Tsys=440 K
tint=1000 hr B=6 MHz No systematics!
MWA (solid black) Aeff=7000 m2
1.5 km core SKA (dotted blue)
Aeff=1 km2
5 km core LOFAR very close to MWA
Survey parameters z=8 Tsys=440 K
tint=1000 hr B=6 MHz No systematics!
MWA (solid black) Aeff=7000 m2
1.5 km core SKA (dotted blue)
Aeff=1 km2
5 km core LOFAR very close to MWA
MWA
SKA
Foreground
limit
(Mpc-1)
Error Estimates: z=12Error Estimates: z=12
Survey parameters z=12 Tsys=1000 K tint=1000 hr B=6 MHz No systematics!
MWA (solid black) Aeff=9000 m2
1.5 km core SKA (dotted blue)
Aeff=1 km2
5 km core
Survey parameters z=12 Tsys=1000 K tint=1000 hr B=6 MHz No systematics!
MWA (solid black) Aeff=9000 m2
1.5 km core SKA (dotted blue)
Aeff=1 km2
5 km core
MWA
SKA
Foreground
limit
(Mpc-1)
That’s a whole lotta trouble…
So what good is it, really?
That’s a whole lotta trouble…
So what good is it, really?
The Global SignalThe Global Signal
Four Phases Dark Ages First Stars First Black Holes Reionization
Four Phases Dark Ages First Stars First Black Holes Reionization
SF (2006)
Reionization BHs Stars Dark Ages
Ly FluctuationsLy Fluctuations
Ly photons decrease TS near sources (Barkana & Loeb 2004) Clustering 1/r2 flux
Strong absorption near dense gas, weak absorption in voids
Ly photons decrease TS near sources (Barkana & Loeb 2004) Clustering 1/r2 flux
Strong absorption near dense gas, weak absorption in voids
Cold, Absorbing
Cold, invisible
Ly FluctuationsLy Fluctuations
Ly photons decrease TS near sources Clustering 1/r2 flux
Strong absorption near dense gas, weak absorption in voids
Eventually saturates when IGM coupled everywhere
Ly photons decrease TS near sources Clustering 1/r2 flux
Strong absorption near dense gas, weak absorption in voids
Eventually saturates when IGM coupled everywhere
Cold, Absorbing
The Pre-Reionization EraThe Pre-Reionization Era
Thick lines: Pop II model, zr=7
Thin lines: Pop III model, zr=7
Dashed: Ly fluctuations
Dotted: Heating fluctuations
Solid: Net signal
Thick lines: Pop II model, zr=7
Thin lines: Pop III model, zr=7
Dashed: Ly fluctuations
Dotted: Heating fluctuations
Solid: Net signal
Ly
X-ray
Net
Pritchard & Furlanetto (2007)
X-ray FluctuationsX-ray Fluctuations
X-ray photons increase TK near sources (Pritchard & Furlanetto 2007) Clustering 1/r2 flux
Hot IGM near dense gas, cool IGM near voids
X-ray photons increase TK near sources (Pritchard & Furlanetto 2007) Clustering 1/r2 flux
Hot IGM near dense gas, cool IGM near voids
Hot
Cool
X-ray and Ly FluctuationsX-ray and Ly Fluctuations
+ =Hot,
emitting
Invisible
The Pre-Reionization EraThe Pre-Reionization Era
Thick lines: Pop II model, zr=7
Thin lines: Pop III model, zr=7
Dashed: Ly fluctuations
Dotted: Heating fluctuations
Solid: Net signal
Thick lines: Pop II model, zr=7
Thin lines: Pop III model, zr=7
Dashed: Ly fluctuations
Dotted: Heating fluctuations
Solid: Net signal
Ly
X-ray
Net
Pritchard & Furlanetto (2007)
X-ray FluctuationsX-ray Fluctuations
+ =Hot,
emitting
Cold, absorbing
The Pre-Reionization EraThe Pre-Reionization Era
Thick lines: Pop II model, zr=7
Thin lines: Pop III model, zr=7
Dashed: Ly fluctuations
Dotted: Heating fluctuations
Solid: Net signal
Thick lines: Pop II model, zr=7
Thin lines: Pop III model, zr=7
Dashed: Ly fluctuations
Dotted: Heating fluctuations
Solid: Net signal
Ly
X-ray
Net
Pritchard & Furlanetto (2007)
X-ray FluctuationsX-ray Fluctuations
+ =
Hot, emitting
The Pre-Reionization EraThe Pre-Reionization Era
Thick lines: Pop II model, zr=7
Thin lines: Pop III model, zr=7
Dashed: Ly fluctuations
Dotted: Heating fluctuations
Solid: Net signal
Thick lines: Pop II model, zr=7
Thin lines: Pop III model, zr=7
Dashed: Ly fluctuations
Dotted: Heating fluctuations
Solid: Net signal
Ly
X-ray
Net
Pritchard & Furlanetto (2007)
21 cm Observations: Reionization
21 cm Observations: Reionization
Mesinger & FurlanettoMesinger & Furlanetto
100 Mpc comoving100 Mpc comoving
Reionization “Simulations”Reionization “Simulations”
Implement in numerical simulation boxes
Step 1: Generate initial conditions
Step 2: Identify galaxies
Implement in numerical simulation boxes
Step 1: Generate initial conditions
Step 2: Identify galaxies
Mesinger & FurlanettoMesinger & Furlanetto
100 Mpc comoving100 Mpc comoving
Biased Galaxy Formation:Peaks and Patches
Biased Galaxy Formation:Peaks and Patches
Galaxies form at peaks in the density field
Threshold decreases with time More galaxies Bigger galaxies
Galaxies form at peaks in the density field
Threshold decreases with time More galaxies Bigger galaxies
Identifying GalaxiesIdentifying Galaxies
Filter density field to find peaks
Use excursion-set barrier to find masses
Adjust locations using Zeldovich approximation
Similar to “peak-patch” method (Bond & Myers 1996), PINOCCHIO, PTHALOS
Filter density field to find peaks
Use excursion-set barrier to find masses
Adjust locations using Zeldovich approximation
Similar to “peak-patch” method (Bond & Myers 1996), PINOCCHIO, PTHALOS
Mesinger & Furlanetto (2007)Mesinger & Furlanetto (2007)
Identifying GalaxiesIdentifying Galaxies
Excellent statistical agreement Large-scale structure Poisson noise
Accurate one-to-one for large galaxies (Bond & Myers 1996)
Excellent statistical agreement Large-scale structure Poisson noise
Accurate one-to-one for large galaxies (Bond & Myers 1996)
Mesinger & Furlanetto (2007)Mesinger & Furlanetto (2007)
Reionization “Simulations”Reionization “Simulations”
Implement in numerical simulation boxes
Step 1: Generate initial conditions
Step 2: Identify galaxies
Implement in numerical simulation boxes
Step 1: Generate initial conditions
Step 2: Identify galaxies
Mesinger & FurlanettoMesinger & Furlanetto
100 Mpc comoving100 Mpc comoving
Photon CountingPhoton Counting
Assume galaxies have fixed ionizing efficiency
Isolated galaxies generate HII regions
Clustered galaxies work together
Assume galaxies have fixed ionizing efficiency
Isolated galaxies generate HII regions
Clustered galaxies work together
Neutral IGM
Ionized IGM
Galaxy
Photon CountingPhoton Counting
Assume galaxies have fixed ionizing efficiency
Isolated galaxies generate HII regions
Clustered galaxies work together
Assume galaxies have fixed ionizing efficiency
Isolated galaxies generate HII regions
Clustered galaxies work together
Reionization “Simulations”Reionization “Simulations”
Mesinger & FurlanettoMesinger & Furlanetto
z=9.75, xz=9.75, xii=0.2=0.2
100 Mpc comoving100 Mpc comoving
Implement in numerical simulation boxes
Step 1: Generate initial conditions
Step 2: Identify galaxies Step 3: Paint on bubbles,
working from outside in
Implement in numerical simulation boxes
Step 1: Generate initial conditions
Step 2: Identify galaxies Step 3: Paint on bubbles,
working from outside in
Reionization “Simulations”Reionization “Simulations”
Mesinger & FurlanettoMesinger & Furlanetto
z=8.75, xz=8.75, xii=0.4=0.4
100 Mpc comoving100 Mpc comoving
Implement in numerical simulation boxes
Step 1: Generate initial conditions
Step 2: Identify galaxies Step 3: Paint on bubbles,
working from outside in
Implement in numerical simulation boxes
Step 1: Generate initial conditions
Step 2: Identify galaxies Step 3: Paint on bubbles,
working from outside in
Reionization “Simulations”Reionization “Simulations”
Implement in numerical simulation boxes
Step 1: Generate initial conditions
Step 2: Identify galaxies Step 3: Paint on bubbles,
working from outside in
Implement in numerical simulation boxes
Step 1: Generate initial conditions
Step 2: Identify galaxies Step 3: Paint on bubbles,
working from outside in
Mesinger & FurlanettoMesinger & Furlanetto
z=8, xz=8, xii=0.6=0.6
100 Mpc comoving100 Mpc comoving
Reionization “Simulations”Reionization “Simulations”
Implement in numerical simulation boxes
Step 1: Generate initial conditions
Step 2: Identify galaxies Step 3: Paint on bubbles,
working from outside in Five hours on desktop!
Implement in numerical simulation boxes
Step 1: Generate initial conditions
Step 2: Identify galaxies Step 3: Paint on bubbles,
working from outside in Five hours on desktop!
Mesinger & FurlanettoMesinger & Furlanetto
z=7.25, xz=7.25, xii=0.8=0.8
100 Mpc comoving100 Mpc comoving
Zahn et al. (2007), Mesinger & Furlanetto (2007)Zahn et al. (2007), Mesinger & Furlanetto (2007)
Success!Success!
Excellent match for large scale features Map details depend on filtering algorithm
Excellent match for large scale features Map details depend on filtering algorithm
Filter A on halos from N-body simulation
Filter B on halos from N-body simulation
Radiative Transfer
Simulation
The 21 cm Power SpectrumThe 21 cm Power Spectrum
MWA
SKA
(Mpc-1)
Mesinger & Furlanetto (2007)
MWA
SKA
21 cm-GalaxyCross-Correlation
21 cm-GalaxyCross-Correlation
Mesinger & FurlanettoMesinger & Furlanettoz=8, xz=8, xii=0.6=0.6
21 cm-Galaxy Cross-Correlation
21 cm-Galaxy Cross-Correlation
Key advantages Unambiguous confirmation of cosmological signal Vastly reduces difficulty of foreground cleaning
Only emission from sources in survey slice contributes
Increase sensitivity and dynamic range Helps with angular structure
Science!
Key advantages Unambiguous confirmation of cosmological signal Vastly reduces difficulty of foreground cleaning
Only emission from sources in survey slice contributes
Increase sensitivity and dynamic range Helps with angular structure
Science!
The 21 cm-GalaxyCross-CorrelationThe 21 cm-GalaxyCross-Correlation
Can be done with LAEs or LBGs
Significant advantages in 21 cm data analysis (SF & AL 2007)
Challenge: wide-field near-IR surveys JWST? JDEM? Ground-based cameras?
Can be done with LAEs or LBGs
Significant advantages in 21 cm data analysis (SF & AL 2007)
Challenge: wide-field near-IR surveys JWST? JDEM? Ground-based cameras?
Lidz, Zahn, & Furlanetto (in prep)Lidz, Zahn, & Furlanetto (in prep)
ConclusionsConclusions
LAE searches beginning to pay off Strange star formation? Robust signatures will be in clustering
The 21 cm transition offers great possibilities Pre-reionization: properties of first sources, cosmology Reionization: morphology and growth of bubbles Experimental challenges still large
Good synergy with other probes of high-z universe! Cross-correlation, Ly searches, quasars…
LAE searches beginning to pay off Strange star formation? Robust signatures will be in clustering
The 21 cm transition offers great possibilities Pre-reionization: properties of first sources, cosmology Reionization: morphology and growth of bubbles Experimental challenges still large
Good synergy with other probes of high-z universe! Cross-correlation, Ly searches, quasars…
See our Physics Reports review (Furlanetto, Oh, & Briggs 2006, astro-ph/0608032) for more information on 21 cm possibilities!