The z > 5 LyThe z > 5 Lyαα forest at high forest at high resolutionresolution

George Becker (Caltech)George Becker (Caltech)

Wal Sargent (Caltech), Michael Rauch (OCIW), Wal Sargent (Caltech), Michael Rauch (OCIW), Rob Simcoe (MIT)Rob Simcoe (MIT)

IAU 199IAU 199March 18, 2005March 18, 2005

MotivationMotivation

Tour of the dataTour of the data

Early indicationsEarly indications Transmission gap evolutionTransmission gap evolution

Thermal constraints on late reionizationThermal constraints on late reionization

SummarySummary

OverviewOverview

Observational constraints on the z ~ 6 IGMObservational constraints on the z ~ 6 IGM

Complete LyComplete Lyαα absorption in z > 6 QSOs absorption in z > 6 QSOs LyLyαα-emitting galaxies-emitting galaxies WMAP WMAP ττee

Each of these is (so far) consistent with a Each of these is (so far) consistent with a variety of reionization scenarios.variety of reionization scenarios.

What else can we observe before going to 21 What else can we observe before going to 21 cm?cm?

LyLyαα at z > 5: The state of the art. at z > 5: The state of the art.

Mean transmitted flux

eff = -Ln(<F>)

Songaila (2004)

What about

•Sub-structure in transmission gaps

•Clustering properties

•Thermal information

H I from proximity effect

???

Going to high resolutionGoing to high resolution

TargetsTargets Brightest z > 5 QSO has i’ = 18.6Brightest z > 5 QSO has i’ = 18.6 Most have i’ (or z’) = 19-20Most have i’ (or z’) = 19-20

New Keck/HIRES CCD arrayNew Keck/HIRES CCD array 2X more sensitive in the far red2X more sensitive in the far red Lower read noiseLower read noise

Our sampleOur sample 7 QSOs7 QSOs 5.1 < z5.1 < zemem < 6.4 < 6.4 2 at z > 6 : SDSS J1030+0524 (z = 6.30) & SDSS 2 at z > 6 : SDSS J1030+0524 (z = 6.30) & SDSS

J1148+5251 (z = 6.42)J1148+5251 (z = 6.42)

HIRES vs. the competitionHIRES vs. the competition

ESI data from G. Djorgovski

SDSS J0836+0054 (zem = 5.80)

FWHM = 7 km/s

FWHM 60 km/s

The The disappearingdisappearing

forestforest

Significant variety among sigtlines…

z = 4.8

z = 4.8

z = 4.8

z = 4.8

z = 4.8

A close upA close up

Narrow transmission spikes

GapsGaps

“Dark Gaps”

“Bright gaps”

Songaila & Cowie (2002), Paschos & Norman (2002)

Bright gap Bright gap characteristicscharacteristics

v

<F>

EW

Gap merging

dn(Gaps) / dzdn(Gaps) / dz

MeanMean

Dark gaps Bright gaps

Paschos & Norman 2004

Line blendingLine blending

Reionization: Thermal predictionsReionization: Thermal predictions Simple reionzation scenarioSimple reionzation scenario

AbruptAbrupt Photo-ionization dominates Photo-ionization dominates

heatingheating

→ → IGM temperature spike IGM temperature spike followed by a rapid cool followed by a rapid cool down down (Hui & Haiman 2003, Miralda-(Hui & Haiman 2003, Miralda-Escudé & Rees 1994, Theuns et al. 2002)Escudé & Rees 1994, Theuns et al. 2002)

Hui & Haiman 2003

Schaye et al. 2000

Lower redshift: measure b(N) cutoff

Problem: No lines in the forest at very high z!

Proximity Proximity zoneszones

b vs. Nb vs. N

bmin ~ 15 – 20 km/s T < 24,000 K

SummarySummary

New HIRES data set covering 5 < z < 6.4New HIRES data set covering 5 < z < 6.4 Significant detail compared to ESISignificant detail compared to ESI

The transmitted flux in the LyThe transmitted flux in the Lyαα forest disappears as forest disappears as transmission (“bright”) gaps get narrower and transmission (“bright”) gaps get narrower and fewer.fewer. Line blanketingLine blanketing Expect F → 0 at z ~ 6.5 based on trends seen at z > 5Expect F → 0 at z ~ 6.5 based on trends seen at z > 5

No (obvious) uniform, isothermal temperature No (obvious) uniform, isothermal temperature spikes in the IGMspikes in the IGM Rules out the most simple scenario of reionization at z~6.5Rules out the most simple scenario of reionization at z~6.5

FutureFuture

A detailed characterization of the z > 5 A detailed characterization of the z > 5 LyLyαα forest forest

Simulation workSimulation work Improved constraints on TImproved constraints on TIGMIGM, , ΧΧH IH I (and (and

therefore on reionization scenarios)therefore on reionization scenarios) from proximity effect measurements?from proximity effect measurements? C IV measurements up to z = 5.5C IV measurements up to z = 5.5 O I forest?O I forest? ??????