quasar absorption lines at high redshift: through a glass darkly

Quasar Absorption Lines at High Redshift:

Through a Glass Darkly

Quasar Absorption Lines at High Redshift:

Through a Glass Darkly

Steve Furlanetto

Caltech

March 18, 2005

Steve Furlanetto

Caltech

March 18, 2005Collaborators: L. Hernquist, A. Loeb,

S.P. Oh, M. Zaldarriaga

The Ly Forest at High Redshifts

The Ly Forest at High Redshifts

Ly forest saturates at z~6!

What have QSO spectra taught us about reionization?

What can we pull out of QSO spectra at z>6? Transmission spikes in

Lyman-series Metal absorption lines

Ly forest saturates at z~6!

What have QSO spectra taught us about reionization?

What can we pull out of QSO spectra at z>6? Transmission spikes in

Lyman-series Metal absorption lines

Becker et al. (2001)

€

τGP ≈ 6x105 xHI

1+ z

10

⎛

⎝ ⎜

⎞

⎠ ⎟3 / 2

SDSS QuasarsSDSS Quasars

SDSS J1030 (z=6.28) No flux for z=6.2-5.98

in Ly or Ly

τ>9.9 (2 mean effective value)

SDSS J1030 (z=6.28) No flux for z=6.2-5.98

in Ly or Ly

τ>9.9 (2 mean effective value)White et al. (2003)

€

τGP ≈ 6x105 xHI

1+ z

10

⎛

⎝ ⎜

⎞

⎠ ⎟3 / 2

€

τ

τ

=fα λαfβ λ β

= 6.24

€

τ

τ

=fα λαfβ λ β

= 6.24

J1030: Mean PropertiesJ1030: Mean Properties

Measured τ +IGM model estimate of ionization rate (assuming uniform)

Appears to change more rapidly at z=6

Difficult to constrain xHI because only probes deep voids

End of reionization? Caveat: poor statistics!

(Paschos & Norman 2004)

Measured τ +IGM model estimate of ionization rate (assuming uniform)

Appears to change more rapidly at z=6

Difficult to constrain xHI because only probes deep voids

End of reionization? Caveat: poor statistics!

(Paschos & Norman 2004)

Fan et al. (2001)

When integrating over large path length, must include cosmic web Transmission samples

unusually underdense voids

Requires model for density distribution!

Extremely difficult to measure xHI!

Different lines sample different densities






Lyman-series Optical DepthsLyman-series Optical DepthsQuasar

Observer

Filament

Visible in Ly

Visible in Ly

Lyman-series Optical DepthsLyman-series Optical Depths











Oh & Furlanetto (2005)

SDSS QuasarsSDSS Quasars

SDSS J1148 (z=6.42) Transmission spikes in

Ly, Ly troughs Residual flux

elsewhere CIV absorber at z=5

Ly emission lines (w/in 1000 km/s)?

Faint continuum?

SDSS J1148 (z=6.42) Transmission spikes in

Ly, Ly troughs Residual flux

elsewhere CIV absorber at z=5

Ly emission lines (w/in 1000 km/s)?

Faint continuum? White et al. (2003)

The Case Against AnInterloper: Residual Flux

The Case Against AnInterloper: Residual Flux

Transmission spikes abruptly stop at z=6.33 for Ly (Oh & Furlanetto 2005)

No continuum break past Ly for z=5 galaxy (Oh & Furlanetto 2005)

Transmission spikes abruptly stop at z=6.33 for Ly (Oh & Furlanetto 2005)

No continuum break past Ly for z=5 galaxy (Oh & Furlanetto 2005)

White et al. (2003)

Residual flux

(5)

Flu

x

Ly atz=5

The IGM Toward J1148+5251The IGM Toward J1148+5251

Residual flux originates at quasar (Oh & Furlanetto 2005) Allows measurement of τ < 15.4 (2), likely τ~7-11, at z=6.18-6.32 (uncertainty

is in IGM density model) IGM is still highly ionized!

SDSS J1030+0524 requires >9.9 (2 ) Difference stronger where transmission spikes appear Large cosmic variance in reionization!

Residual flux originates at quasar (Oh & Furlanetto 2005) Allows measurement of τ < 15.4 (2), likely τ~7-11, at z=6.18-6.32 (uncertainty

is in IGM density model) IGM is still highly ionized!

SDSS J1030+0524 requires >9.9 (2 ) Difference stronger where transmission spikes appear Large cosmic variance in reionization!

White et al. (2003)

Ly atz=6.33Residual

flux (5)

Flu

x

Ly atz=5

The Topology of ReionizationThe Topology of Reionization

Simple semi-analytic models treat HII regions around individual galaxies

Simulations show clustering drives evolution!

Simple semi-analytic models treat HII regions around individual galaxies

Simulations show clustering drives evolution!

Sokasian et al. (2003)

z=8.74z=8.74

z=7.24z=7.24

13 comoving Mpc13 comoving Mpc

Bubble SizesBubble Sizes

SF, MZ, LH (2004a)SF, MZ, LH (2004a)

xH=0.96

xH=0.70

xH=0.25

Bubble Sizes: How Big?Bubble Sizes: How Big?

For bubble to grow, ionizing photons must reach bubble wall

Mean free path depends on density structure of IGM (xH ~ 2)

Limit kicks in when R>10-30 Mpc (Furlanetto & Oh, in prep)

For bubble to grow, ionizing photons must reach bubble wall

Mean free path depends on density structure of IGM (xH ~ 2)

Limit kicks in when R>10-30 Mpc (Furlanetto & Oh, in prep)

QSO SpectraQSO Spectra

What are these transmission spikes? Post-reionization features? Voids? Bubbles?

What are these transmission spikes? Post-reionization features? Voids? Bubbles?

White et al. (2003)

Flu

x

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

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

Can we probe mid/late stages of reionization with QSO/GRB 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

Can we probe mid/late stages of reionization with QSO/GRB spectra?

SF, LH, MZ (2004)

ObservedFeature

Studying the IGM StructureStudying the IGM Structure

Mean free path ultimately constrained by dense neutral blobs (?)

Left to right: max mfp=(10, 20, 30, 60, 600) comoving Mpc (all at xi=0.96)

Are we interpreting the tail end of reionization properly?

Mean free path ultimately constrained by dense neutral blobs (?)

Left to right: max mfp=(10, 20, 30, 60, 600) comoving Mpc (all at xi=0.96)

Are we interpreting the tail end of reionization properly?

SF, SPO (in prep)

Complex ReionizationComplex Reionization

WMAP: τ~0.17; reionization begins early SDSS: reionization ends at z=6 Reconcile through complicated source physics: Feedback!, e.g.

Photoionization Minihalos Metal Enrichment

WMAP: τ~0.17; reionization begins early SDSS: reionization ends at z=6 Reconcile through complicated source physics: Feedback!, e.g.

Photoionization Minihalos Metal Enrichment

Wyithe & Loeb (2003)

Complex Reionization:Metal Enrichment

Complex Reionization:Metal Enrichment

Ejection by supernova winds is most likely mechanism

Regulates transition from Pop III (massive?) star formation to Pop II

Complex and extended Highly inhomogeneous New galaxies form Pop III

stars, even late (?) Extended no sharp features

in reionization Extremely uncertain timing and

extent

Ejection by supernova winds is most likely mechanism

Regulates transition from Pop III (massive?) star formation to Pop II

Complex and extended Highly inhomogeneous New galaxies form Pop III

stars, even late (?) Extended no sharp features

in reionization Extremely uncertain timing and

extent

SF, AL (2005)

Increasing Wind Efficiency

Reionization

Metal Absorption LinesMetal Absorption Lines

(1+zs)Ly (1+zs)metal

SDSS collaboration

Can probe Ly/metal< (1+z)/(1+zs) < 1

Metal Absorption LinesMetal Absorption Lines

Important lines: Most abundant elements produced by Type II SNe: C

(YCSN=0.1 Msun), O (0.5 Msun), Si (0.06 Msun), Fe

(0.07 Msun) Most abundant elements produced by VMS SNe: C

(YCSN=4.1 Msun), O (44 Msun), Si (16 Msun), Fe (6.4

Msun) Ionization states determined by radiation background

and nearby galaxy

CII, OI, SiII, FeII for neutral medium CIV, SiIV for ionized medium

Important lines: Most abundant elements produced by Type II SNe: C

(YCSN=0.1 Msun), O (0.5 Msun), Si (0.06 Msun), Fe

(0.07 Msun) Most abundant elements produced by VMS SNe: C

(YCSN=4.1 Msun), O (44 Msun), Si (16 Msun), Fe (6.4

Msun) Ionization states determined by radiation background

and nearby galaxy

CII, OI, SiII, FeII for neutral medium CIV, SiIV for ionized medium

MethodologyMethodology

One wind bubble per halo Star formation history from extended Press-Schechter

Mechanical Luminosity provided by SN rate (and hence SFR)

Use thin-shell approximation (Tegmark et al. 1993) All mass confined to spherical thin shell (no fragmentation) Sweeps up all IGM mass Driving force is hot bubble interior

Consider low-ionization states in spherical shells Free parameters: f*, ESN, IMF, fw (and others)

One wind bubble per halo Star formation history from extended Press-Schechter

Mechanical Luminosity provided by SN rate (and hence SFR)

Use thin-shell approximation (Tegmark et al. 1993) All mass confined to spherical thin shell (no fragmentation) Sweeps up all IGM mass Driving force is hot bubble interior

Consider low-ionization states in spherical shells Free parameters: f*, ESN, IMF, fw (and others)

Wind Characteristics: Shell RadiusWind Characteristics: Shell Radius

Points: Monte Carlo model

Solid line: Halo virial radius

R ~ E1/3 (at constant mass)

R ~ M1/5 (at constant f*)

Points: Monte Carlo model

Solid line: Halo virial radius

R ~ E1/3 (at constant mass)

R ~ M1/5 (at constant f*)

SF, AL (2003)

Wind Characteristics: OI Equivalent Width

Wind Characteristics: OI Equivalent Width

Crosses: z=20 Dashes: z=16 Triangles: z=12 Points: z=8 W ~ M/R2 ~ M3/5

Strongest absorbers surround largest galaxies

Crosses: z=20 Dashes: z=16 Triangles: z=12 Points: z=8 W ~ M/R2 ~ M3/5

Strongest absorbers surround largest galaxies

SF, AL (2003)

Absorption StatisticsAbsorption Statistics

Scalo IMF, f*=0.1 OI 1302 is shown One absorption line

per wind (no fragmentation)

Wtot depends on f*, shape depends on fw

Q~(10-4,10-3,0.01,0.1)

Scalo IMF, f*=0.1 OI 1302 is shown One absorption line

per wind (no fragmentation)

Wtot depends on f*, shape depends on fw

Q~(10-4,10-3,0.01,0.1)

z=20

z=16

z=12

z=8

SF, AL (2003)

What Can We Learn?What Can We Learn?

z=8,f*=0.1 Net absorption similar for low,

high-ionization states Reveals enrichment patterns,

ionizing background (+clumping)

Hot gas will remain invisible: OVI < Ly

Identifying lines may be a challenge Doublets straightforward Others require several lines

together? And distinguish from noise!

z=8,f*=0.1 Net absorption similar for low,

high-ionization states Reveals enrichment patterns,

ionizing background (+clumping)

Hot gas will remain invisible: OVI < Ly

Identifying lines may be a challenge Doublets straightforward Others require several lines

together? And distinguish from noise!

SF, AL (2003)


Some models require “prompt enrichment” by VMS stars in minihalos: Q~0.1-1 at high redshifts

Expect significant absorption, e.g. CII: τ~0.16 (Z/10-2.5 Zsun) (1+z/7)3/2

Actually expect forest of features from density structure

Do background sources exist?

Some models require “prompt enrichment” by VMS stars in minihalos: Q~0.1-1 at high redshifts

Expect significant absorption, e.g. CII: τ~0.16 (Z/10-2.5 Zsun) (1+z/7)3/2

Actually expect forest of features from density structure

Do background sources exist?

Metal Lines and ReionizationMetal Lines and Reionization

OI/HI in tight charge-exchange equilibrium τ~0.14 (Z/10-2.5 Zsun) for

equivalent GP trough

Dense regions enriched first but ionized last “forest” of (unsaturated) OI lines near reionization

Stretch into near-IR: sky lines difficult!

OI/HI in tight charge-exchange equilibrium τ~0.14 (Z/10-2.5 Zsun) for

equivalent GP trough

Dense regions enriched first but ionized last “forest” of (unsaturated) OI lines near reionization

Stretch into near-IR: sky lines difficult!

Oh (2002)

SummarySummary

SDSS quasars indicate something dramatic happens at z~6, but its nature unclear Huge cosmic variance between two lines of sight!

Models of reionization suggest variations in on large scales Allows transmission in QSO spectra when xHI<0.25: study transition

from “bubble-dominated” to “web-dominated” universe Other probes of topology: 21 cm emission, kSZ effect, Ly galaxies

Metal lines with >Ly must appear beyond reionization! Trace course of enrichment (crucial piece of extended reionization) “OI forest” at tail end of reionization Expectations far from clear: hugely simplified models so far!

SDSS quasars indicate something dramatic happens at z~6, but its nature unclear Huge cosmic variance between two lines of sight!

Models of reionization suggest variations in on large scales Allows transmission in QSO spectra when xHI<0.25: study transition

from “bubble-dominated” to “web-dominated” universe Other probes of topology: 21 cm emission, kSZ effect, Ly galaxies

Metal lines with >Ly must appear beyond reionization! Trace course of enrichment (crucial piece of extended reionization) “OI forest” at tail end of reionization Expectations far from clear: hugely simplified models so far!

The Case Against anInterloper: Transmission Spikes

The Case Against anInterloper: Transmission Spikes If emission lines from

intervening galaxy, should be extended source (>1 arcsec)

White et al. (2005) observed with narrowband ACS filter: point source!

z=5 galaxy does help clear Ly forest

If emission lines from intervening galaxy, should be extended source (>1 arcsec)

White et al. (2005) observed with narrowband ACS filter: point source!

z=5 galaxy does help clear Ly forest

SDSS Quasars: “Proximity Zones”SDSS Quasars: “Proximity Zones”

Ly/Ly flux ratios J1030 has region with Ly

transmission but no Ly Requires smooth damping

wing component xHI>0.1? (Mesinger & Haiman 2004)

Does not appear in J1148 QSO redshift + edge of

transmission measure size of HII region? Luminosity + lifetime

xHI>0.1 (Wyithe & Loeb 2004) But see Yu & Lu (2004)

Ly/Ly flux ratios J1030 has region with Ly

transmission but no Ly Requires smooth damping

wing component xHI>0.1? (Mesinger & Haiman 2004)

Does not appear in J1148 QSO redshift + edge of

transmission measure size of HII region? Luminosity + lifetime

xHI>0.1 (Wyithe & Loeb 2004) But see Yu & Lu (2004)

White et al. (2003)


Simple ansatz:

mion = mgal

= f* fesc N/b / (1+nrec)

Then condition for a region to be fully ionized is

fcoll > -1

Simple ansatz:

mion = mgal



fcoll > -1

Neutral IGM

Ionized IGM

Galaxy


Simple ansatz:

mion = mgal



fcoll > -1

Simple ansatz:

mion = mgal



fcoll > -1

Neutral IGM

Ionized IGM?

Galaxy


Simple ansatz:

mion = mgal

= f* fesc N/b / (1+nrec) Then condition for a

region to be fully ionized is

fcoll > -1

Can construct an analog of Press-Schechter mass function = mass function of ionized regions

Simple ansatz:

mion = mgal

= f* fesc N/b / (1+nrec) Then condition for a

region to be fully ionized is

fcoll > -1

Can construct an analog of Press-Schechter mass function = mass function of ionized regions

Neutral IGM

Ionized IGM

Galaxy

Bubble Sizes: Why?Bubble Sizes: Why?

Mostly independent of redshift at fixed xH

Depends primarily on the bias of ionizing sources

Solid lines: f*=const

Dashed lines: f*~m2/3

Mostly independent of redshift at fixed xH

Depends primarily on the bias of ionizing sources

Solid lines: f*=const

Dashed lines: f*~m2/3

xH=0.8

xH=0.25

SF, MZ, LH (in prep)SF, MZ, LH (in prep)

Metal Pollution: Filling FactorMetal Pollution: Filling Factor

Different curves show f*=0.01, 0.1, 0.5, from bottom to top

Solid: H2 cooling Dotted: Atomic

cooling Ignores galaxy

clustering!

Different curves show f*=0.01, 0.1, 0.5, from bottom to top

Solid: H2 cooling Dotted: Atomic

cooling Ignores galaxy

clustering!

FL03

FL03


z=8 Solid: f*=0.5, f*=0.1,

f*=0.01 Dashed: vary fraction

of SN energy in wind

z=8 Solid: f*=0.5, f*=0.1,

f*=0.01 Dashed: vary fraction

of SN energy in wind

quasar absorption lines at high redshift: through a glass darkly

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