the topology of reionization
TRANSCRIPT
The Topology of Reionization
Dr. Steven Furlanetto, Caltech (KITP Galaxy-IGM Program 12/07/04) 1
The Topology of ReionizationThe Topology of Reionization
Steve FurlanettoDecember 7, 2004Steve Furlanetto
December 7, 2004
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OutlineOutline
� Introduction� Topology� Observational Probes
� QSO spectra� Lyα galaxies� Secondary CMB anisotropies� 21 cm tomography
� The Mileura Widefield Array
� Introduction� Topology� Observational Probes
� QSO spectra� Lyα galaxies� Secondary CMB anisotropies� 21 cm tomography
� The Mileura Widefield Array
The Topology of Reionization
Dr. Steven Furlanetto, Caltech (KITP Galaxy-IGM Program 12/07/04) 2
What Is Reionization?What Is Reionization?
� Why is it interesting?� Hallmark event of first sources� Measures interaction with IGM� Affects z=0 objects
� What do we expect?� Rapid phase transition� z~6-20
� What do we want to know?� When?� Why?
� How?
� Why is it interesting?� Hallmark event of first sources� Measures interaction with IGM� Affects z=0 objects
� What do we expect?� Rapid phase transition� z~6-20
� What do we want to know?� When?� Why?
� How?
Sokasian et al. (2003)
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Comparing the ObservationsComparing the Observations
� WMAP: begins at z>14� Lya forest temperature: z<10� Lya emitters: mostly ionized at
z=6.5� GP trough: changing rapidly at
z=6.1, variability� QSO proximity zones: partly
neutral at z=6.3� Together imply complex time
history!
� WMAP: begins at z>14� Lya forest temperature: z<10� Lya emitters: mostly ionized at
z=6.5� GP trough: changing rapidly at
z=6.1, variability� QSO proximity zones: partly
neutral at z=6.3� Together imply complex time
history!
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GP Trough
Temperature
WMAP
Lyαααα Gals
Proximity Zones
The Topology of Reionization
Dr. Steven Furlanetto, Caltech (KITP Galaxy-IGM Program 12/07/04) 3
The Topology of ReionizationThe Topology of Reionization
� Simple semi-analytic models treat HII regions around individual galaxies
� Clustered sources� Large HII regions
� Consistent with simulations and analytic work (Barkana & Loeb 2004)
� Simple semi-analytic models treat HII regions around individual galaxies
� Clustered sources� Large HII regions
� Consistent with simulations and analytic work (Barkana & Loeb 2004)
Sokasian et al. (2003)
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Real Inhomogeneity!Real Inhomogeneity!
� SDSS J1030 (z=6.28)� No flux at z=6.2-5.98 in
either Lyα or Lyβ� τα>9.9 (2σ; mean effective
value)
� SDSS J1148 (z=6.42)� Transmission spikes in
Lyα, Lyβ troughs� Residual flux elsewhere� τα < 14.3 (2σ), likely τα~6-
10 (from clean Lyγ trough; Oh & Furlanetto 2004)
� SDSS J1030 (z=6.28)� No flux at z=6.2-5.98 in
either Lyα or Lyβ� τα>9.9 (2σ; mean effective
value)
� SDSS J1148 (z=6.42)� Transmission spikes in
Lyα, Lyβ troughs� Residual flux elsewhere� τα < 14.3 (2σ), likely τα~6-
10 (from clean Lyγ trough; Oh & Furlanetto 2004)
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The Topology of Reionization
Dr. Steven Furlanetto, Caltech (KITP Galaxy-IGM Program 12/07/04) 4
The Topology of ReionizationThe Topology of Reionization
� Simple ansatz:
mion = ζ mgal
ζ = f* fesc Nγ/b / (1+nrec)
� Then condition for a region to be fully ionized is
fcoll > ζ-1
� Simple ansatz:
mion = ζ mgal
ζ = f* fesc Nγ/b / (1+nrec)
� Then condition for a region to be fully ionized is
fcoll > ζ-1
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The Topology of ReionizationThe Topology of Reionization
� Simple ansatz:
mion = ζ mgal
ζ = f* fesc Nγ/b / (1+nrec)
� Then condition for a region to be fully ionized is
fcoll > ζ-1
� Simple ansatz:
mion = ζ mgal
ζ = f* fesc Nγ/b / (1+nrec)
� Then condition for a region to be fully ionized is
fcoll > ζ-1
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The Topology of Reionization
Dr. Steven Furlanetto, Caltech (KITP Galaxy-IGM Program 12/07/04) 5
The Topology of ReionizationThe Topology of Reionization
� Simple ansatz:
mion = ζ mgal
ζ = f* fesc Nγ/b / (1+nrec)
� Then condition for a region to be fully ionized is
fcoll > ζ-1
� Simple ansatz:
mion = ζ mgal
ζ = f* fesc Nγ/b / (1+nrec)
� Then condition for a region to be fully ionized is
fcoll > ζ-1
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The Topology of ReionizationThe Topology of Reionization
� Simple ansatz:mion = ζ mgal
ζ = f* fesc Nγ/b / (1+nrec)
� Then condition for a region to be fully ionized is
fcoll > ζ-1
� Can construct an analog of Press-Schechter mass function = mass function of ionized regions
� Simple ansatz:mion = ζ mgal
ζ = f* fesc Nγ/b / (1+nrec)
� Then condition for a region to be fully ionized is
fcoll > ζ-1
� Can construct an analog of Press-Schechter mass function = mass function of ionized regions
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The Topology of Reionization
Dr. Steven Furlanetto, Caltech (KITP Galaxy-IGM Program 12/07/04) 6
The Topology of ReionizationThe Topology of Reionization
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The Topology of ReionizationThe Topology of Reionization
� Large bubbles � easy to observe
� Large bubbles � easy to observe
The Topology of Reionization
Dr. Steven Furlanetto, Caltech (KITP Galaxy-IGM Program 12/07/04) 7
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The Topology of ReionizationThe Topology of Reionization
� Large bubbles � easy to observe
� Characteristic size �easy to observe
� Large bubbles � easy to observe
� Characteristic size �easy to observe
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The Topology of ReionizationThe Topology of Reionization
� Large bubbles � easy to observe
� Characteristic size �easy to observe
� Trust no one!!!
� Large bubbles � easy to observe
� Characteristic size �easy to observe
� Trust no one!!!
The Topology of Reionization
Dr. Steven Furlanetto, Caltech (KITP Galaxy-IGM Program 12/07/04) 8
The Topology of ReionizationThe Topology of Reionization
� Mostly independent of redshift at fixed xH
� Depends primarily on the bias of ionizing sources
� Solid lines: f*=const� Dashed lines: f*~m2/3
� Other factors…� Clumping/recombinations� Bursty star formation� Feedback!
� Mostly independent of redshift at fixed xH
� Depends primarily on the bias of ionizing sources
� Solid lines: f*=const� Dashed lines: f*~m2/3
� Other factors…� Clumping/recombinations� Bursty star formation� Feedback!
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Observational ProbesObservational Probes
� Quasar/GRB spectra
� Lyα Emitters� Secondary CMB Anisotropies� Redshifted 21 cm emission
� Quasar/GRB spectra
� Lyα Emitters� Secondary CMB Anisotropies� Redshifted 21 cm emission
The Topology of Reionization
Dr. Steven Furlanetto, Caltech (KITP Galaxy-IGM Program 12/07/04) 9
QSO/GRB SpectraQSO/GRB Spectra
� Transmission spike at z=6.08 appears in both Lyα and Lyβ: real even if you accept interloper
� Lyβ spikes also (probably) real (Oh & Furlanetto 2004)� What do they tell us???
� Transmission spike at z=6.08 appears in both Lyα and Lyβ: real even if you accept interloper
� Lyβ spikes also (probably) real (Oh & Furlanetto 2004)� What do they tell us???
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Transmission SpikesTransmission Spikes
� For transmission:� Must eliminate resonant
absorption: pass close to ionizing source
� Must eliminate damping wing absorption: pass through large HII region
� For isolated galaxies, NO features before reionization (Barkana 2002)
� For transmission:� Must eliminate resonant
absorption: pass close to ionizing source
� Must eliminate damping wing absorption: pass through large HII region
� For isolated galaxies, NO features before reionization (Barkana 2002) IGM HI
QSO
QSO
The Topology of Reionization
Dr. Steven Furlanetto, Caltech (KITP Galaxy-IGM Program 12/07/04) 10
QSO Absorption SpectraQSO Absorption Spectra
� Include clustering of sources: eliminate damping wing absorption
� Curves have xH=(0.1,0.15,0.2,0.25) at z=6.1
� Simple model: � Includes inhomogeneous IGM� Naïve distribution of sources
within bubbles� No recombinations
� Spectra during/after reionization need MUCH better modeling (Oh & Furlanetto 2004)
� Include clustering of sources: eliminate damping wing absorption
� Curves have xH=(0.1,0.15,0.2,0.25) at z=6.1
� Simple model: � Includes inhomogeneous IGM� Naïve distribution of sources
within bubbles� No recombinations
� Spectra during/after reionization need MUCH better modeling (Oh & Furlanetto 2004)
SF, LH, MZ (2004)
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Lyα Emitters and TopologyLyα Emitters and Topology
� Total optical depth in Lyαtransition:
� “Damping wing” absorption from neutral IGM� Depends on distance to edge of
HII region
� “Resonant absorption” from gas inside the HII region� Determined by local ionizing flux
� Total optical depth in Lyαtransition:
� “Damping wing” absorption from neutral IGM� Depends on distance to edge of
HII region
� “Resonant absorption” from gas inside the HII region� Determined by local ionizing flux
IGM HI
HII region aroundsmall galaxy
HII region aroundclustered sources
τGP ≈ 6x105 xHI
1+ z
10
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The Topology of Reionization
Dr. Steven Furlanetto, Caltech (KITP Galaxy-IGM Program 12/07/04) 11
Lyα Galaxy SurveysLyα Galaxy Surveys
� Resonant absorption determined by galaxy’s luminosity� Destroys blue side� Red side unaffected
� Damping wing absorption determined by size of HII region� 109 Msun galaxy at z=10 has
(75%, 40%, 20%, 3%) chance to be in HII regions larger than shown if xH=0.5
� Surveys can measure distribution of bubble sizes
� Resonant absorption determined by galaxy’s luminosity� Destroys blue side� Red side unaffected
� Damping wing absorption determined by size of HII region� 109 Msun galaxy at z=10 has
(75%, 40%, 20%, 3%) chance to be in HII regions larger than shown if xH=0.5
� Surveys can measure distribution of bubble sizes
SF, LH, MZ (2004)
The Evolving Luminosity Function
The Evolving Luminosity Function
� Intrinsic luminosity function depends on geometry, kinematics, dust, etc.
� But those factors (probably, more or less) constant with redshift
� Thick black line: post-reionization� Blue line: xH=0.25� Magenta line: xH=0.5� Red line: xH=0.75� Thin black line: ruled out by
Malhotra & Rhoads (2004)� Lyα galaxies should be visible
farther back into reionization epoch
� Intrinsic luminosity function depends on geometry, kinematics, dust, etc.
� But those factors (probably, more or less) constant with redshift
� Thick black line: post-reionization� Blue line: xH=0.25� Magenta line: xH=0.5� Red line: xH=0.75� Thin black line: ruled out by
Malhotra & Rhoads (2004)� Lyα galaxies should be visible
farther back into reionization epoch
SF, LH, MZ (in prep)
The Topology of Reionization
Dr. Steven Furlanetto, Caltech (KITP Galaxy-IGM Program 12/07/04) 12
Secondary CMB AnisotropiesSecondary CMB Anisotropies
� Nonlinear kSZ (Ostriker-Vishniac)� Determined by nonlinear
structure formation� Depends slightly on
reionization redshift
� Patchy reionization (Gruzinov & Hu 1998; Knox et al. 1998; Santos et al. 2003)� Anisotropies from ionized
bubbles� Depends on bubble scale
� Nonlinear kSZ (Ostriker-Vishniac)� Determined by nonlinear
structure formation� Depends slightly on
reionization redshift
� Patchy reionization (Gruzinov & Hu 1998; Knox et al. 1998; Santos et al. 2003)� Anisotropies from ionized
bubbles� Depends on bubble scale
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Secondary CMB Anisotropies IISecondary CMB Anisotropies II
� Signal especially large for extended reionization� Patchiness persists
over long time interval� Little information about
source details
� Signal especially large for extended reionization� Patchiness persists
over long time interval� Little information about
source details
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The Topology of Reionization
Dr. Steven Furlanetto, Caltech (KITP Galaxy-IGM Program 12/07/04) 13
21 cm Tomography21 cm Tomography
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21 cm Tomography21 cm Tomography
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21 cm Tomography21 cm Tomography
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21 cm Tomography21 cm Tomography
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21 cm Tomography21 cm Tomography
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The 21 cm SignalThe 21 cm Signal
� Observable quantity is brightness temperature� Diffuse IGM has (Madau et al. 1997)
� Depends on spin temperature TS=excitation temperature of 21 cm transition� Determined by CMB, collisions (inefficient), Lyα photons� During reionization, Ts>>TCMB is most plausible� In that case, nearly independent of temperature
� Observable quantity is brightness temperature� Diffuse IGM has (Madau et al. 1997)
� Depends on spin temperature TS=excitation temperature of 21 cm transition� Determined by CMB, collisions (inefficient), Lyα photons� During reionization, Ts>>TCMB is most plausible� In that case, nearly independent of temperature
δTb ≈ 23x HI (1+ δ) 1+ z
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The Topology of Reionization
Dr. Steven Furlanetto, Caltech (KITP Galaxy-IGM Program 12/07/04) 20
Characterizing the Topology: The Power Spectrum
Characterizing the Topology: The Power Spectrum
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The Power SpectrumThe Power Spectrum
� Dotted: z=18, xH=0.96� Short-dashed: z=15, xH=0.81� Long-dashed: z=13, xH=0.52� Solid: z=12, xH=0.26
� Dotted: z=18, xH=0.96� Short-dashed: z=15, xH=0.81� Long-dashed: z=13, xH=0.52� Solid: z=12, xH=0.26
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xH=0.81� Solid blue: z=12, xH=0.26
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The Topology of Reionization
Dr. Steven Furlanetto, Caltech (KITP Galaxy-IGM Program 12/07/04) 21
Other Statistical MeasuresOther Statistical Measures
� xH field is not gaussian �power spectrum only part of the story
� Can construct pixel distribution function in any model� Solid: fcoll model� Dashed: void model� Dotted: uniform ionization
� Qualitatively different distributions!
� xH field is not gaussian �power spectrum only part of the story
� Can construct pixel distribution function in any model� Solid: fcoll model� Dashed: void model� Dotted: uniform ionization
� Qualitatively different distributions!
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So Can It Be Done?So Can It Be Done?
� Primeval Structure Telescope� Begin full scale construction 2005
� Dedicated instrument
� VLA survey� Targeted at 192-200 MHz
� LOw Frequency ARray� 30-240 MHz
� Aims for “first light” in ~2007
� Mileura Widefield Array� Square Kilometer Array
� Next generation radio telescope
� Many years away: initial operations sometime around 2020
� Primeval Structure Telescope� Begin full scale construction 2005
� Dedicated instrument
� VLA survey� Targeted at 192-200 MHz
� LOw Frequency ARray� 30-240 MHz
� Aims for “first light” in ~2007
� Mileura Widefield Array� Square Kilometer Array
� Next generation radio telescope
� Many years away: initial operations sometime around 2020
The Topology of Reionization
Dr. Steven Furlanetto, Caltech (KITP Galaxy-IGM Program 12/07/04) 22
Mileura Widefield ArrayMileura Widefield Array
� Low-frequency radio telescope in Western Australia
� First observations with demonstrator (Maude) planned for 2007
� Collaborators include MIT, Melbourne, CfA, ATNF + others (SF, Briggs, Carilli)
� Also transients, heliosphere
� Low-frequency radio telescope in Western Australia
� First observations with demonstrator (Maude) planned for 2007
� Collaborators include MIT, Melbourne, CfA, ATNF + others (SF, Briggs, Carilli)
� Also transients, heliosphere
Mileura Widefield ArrayMileura Widefield Array
� Instrument characteristics� Radio-quiet site� 500 16-element antennae
(8000 m2) in 1.5 km distribution
� Full cross-correlation of all 500 antennae
� 80-300 MHz (z<16)� Many (4+) MHz
instantaneous bandwidth at 8 kHz resolution
� 400-1000 square degree field of view
� Instrument characteristics� Radio-quiet site� 500 16-element antennae
(8000 m2) in 1.5 km distribution
� Full cross-correlation of all 500 antennae
� 80-300 MHz (z<16)� Many (4+) MHz
instantaneous bandwidth at 8 kHz resolution
� 400-1000 square degree field of view
The Topology of Reionization
Dr. Steven Furlanetto, Caltech (KITP Galaxy-IGM Program 12/07/04) 23
Mileura Widefield ArrayMileura Widefield Array
� Instrument emphasizes:� Survey speed� Data quality� Calibration
� Simulated data shown (neglecting foreground subtraction; 4 MHz band, 100 hrs)
� Also image individual (but large) HII regions at z~6.5
� Instrument emphasizes:� Survey speed� Data quality� Calibration
� Simulated data shown (neglecting foreground subtraction; 4 MHz band, 100 hrs)
� Also image individual (but large) HII regions at z~6.5
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ConclusionsConclusions
� Reionization is complex and inhomogeneous� All current constraints are difficult to interpret!
� Topology carries enormous amount of information about source/IGM interactions
� Observational probes are on their way� Careful interpretation of QSO/GRB spectra (SDSS,
Swift: soon!)� Lyα galaxies (soon?)� Secondary CMB anisotropies (~3 years)� 21 cm emission (~3 years)
� Reionization is complex and inhomogeneous� All current constraints are difficult to interpret!
� Topology carries enormous amount of information about source/IGM interactions
� Observational probes are on their way� Careful interpretation of QSO/GRB spectra (SDSS,
Swift: soon!)� Lyα galaxies (soon?)� Secondary CMB anisotropies (~3 years)� 21 cm emission (~3 years)