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Probing Reionization & Galaxy Evolution by High-z Lyα Emitters. z=6.96 LAE. Kazuaki Ota Cosmic Radiation Lab. RIKEN Institute of Physical and Chemical Research. Outline. I. Goal: to address the question, When did reionization end? II. Approach: Lyα Emitters III. Result IV. Conclusion - PowerPoint PPT Presentation
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Kazuaki OtaCosmic Radiation Lab.
RIKEN Institute of Physical and
Chemical Research
Probing Reionization & Galaxy Evolution by High-z Lyα Emitters
z=6.96 LAE
OutlineOutline
I. Goal: to address the question,I. Goal: to address the question,
When did reionizationWhen did reionization end?end?
II. Approach: LyαII. Approach: Lyα Emitters Emitters
III. ResultIII. Result
IV. ConclusionIV. Conclusion
V. Upcoming ProjectsV. Upcoming Projects
OutlineOutline
I. Goal: to address the question,I. Goal: to address the question,
When did reionizationWhen did reionization end?end?
II. Approach: LyαII. Approach: Lyα Emitters Emitters
III. ResultIII. Result
IV. ConclusionIV. Conclusion
V. Upcoming ProjectsV. Upcoming Projects
WMAP (CMB)WMAP (CMB)Dunkley et al. 2008
zreion=11.0±1.4zreion > 6.7 (3σ
limit)
When did reionization end?
γ-ray burstγ-ray burstTotani et al. 2006neutral fraction0< XHI < 17 – 60%
GP trough
quasarsquasarsFan et al. 2006neutral fractionXHI ~ 1 – 4%
z=6.3
z~6.2
Fan et al.2006 ARAA
Neu
tral
Fra
ctio
n X
HI
Redshift z
Reionization Scenario: Late vs. Early
Fan et al.2006 ARAARedshift z
Neu
tral
Fra
ctio
n X
HI
z=7z=6.6Lyα Emitters(LAEs)
Our Result: LAEs support late reionization
Reionization might have ended at z~6.Reionization might have ended at z~6.
OutlineOutline
I. Goal: to address the question,
When did reionizationWhen did reionization end?end?
II. Approach: LyαII. Approach: Lyα Emitters Emitters
III. ResultIII. Result
IV. ConclusionIV. Conclusion
V. Upcoming ProjectsV. Upcoming Projects
z=5.7z=6.6 z=7
If NF increases beyond z~6,observed LAE number density could decrease beyond z~6.
Fan et al. 2002
GP troughReionization Probe : z~6 Quasars Neutral Fraction1 – 4%
Iye et al. 2006
Lyα emitters (LAEs)
Filt
er R
esp
on
se
Wavelength (A)
Narrowband Filters to Detect LyNarrowband Filters to Detect Lyα
z=5.7Lyα
z=6.6
z=7LAE
z=7
Skylines
Sample Selection: NB excessSample Selection: NB excess
z=5.7 LAEs z=6.6 LAEs
Shimasaku et al.2006 Taniguchi et al.2005Kashikawa et al.2006
Sample Selection of z=7LAEsSample Selection of z=7LAEs
i’ – z’ [mag]
z’ –
NB
973
[mag
] 12
Detected in only NB973
3:z=6.6LAE
Model z=7 LAE
Ota et al.2008
Spectroscopic confirmationSpectroscopic confirmation
Shimasaku et al.2006z=5.7 LAEs 86% complete
Kashikawa et al.2006z=6.6 LAEs 89% complete
Iye, Ota et al.2006z=7 LAE
Subaru Deep Field Suprime-Cam876 arcmin2
SDF Latest LAE Samples Image Spec. z=5.7 89 34 Shimasaku et al. 2006z=6.6 58 17 Kashikawa et al. 2006z=7.0 2 1 Ota et al. 2008
Target Sky Region & SamplesTarget Sky Region & Samples3σ, 2” aper. Limit. Mag. B ≤ 28.45 V ≤ 27.74 R ≤ 27.80 i’ ≤ 27.43 z’ ≤ 26.62 NB816 ≤ 26.63 (z=5.7) NB921 ≤ 26.54 (z=6.6) NB973 ≤ 25.47 (z=7.0)
OutlineOutline
I. Goal: to address the question,
When did reionizationWhen did reionization end?end?
II. Approach: Lyα Emitters
III. ResultIII. Result
IV. ConclusionIV. Conclusion
V. Upcoming ProjrctsV. Upcoming Projrcts
Did reionization end at z~6?
Does HI increase beyond z=6?
Comparison of z<6 & z>6 LAE’s Comparison of z<6 & z>6 LAE’s Lyα Luminosity Function (LF)Lyα Luminosity Function (LF)
LAE evolution modelLAE evolution model
Increase in HIIncrease in HIgalaxy evolutiongalaxy evolution
Lyα LF ( Observed )z=5.7Phot■z=6.6Phot●z=6.6Spec▲z=7.0Spec◆
Lyα Luminosity log[L(Lyα) erg/s]
Num
ber
dens
ity lo
g[n(
>L)
Mpc
-3]
Decline in n(>L) ・ galaxy evolution?・ increase in HI?・ both?
z=7LAEdetectionlimit
Starburst galaxy
Quiescent galaxy
A LAE Evolution ModelA LAE Evolution Model (Kobayashi et al.2007)(Kobayashi et al.2007)
Lyα emitters
IGM transmission to Lyα photons
Lyα escape fraction
Observed Lyα luminosity
0 ≤ TLyα ≤ 1IGM
fesc =0Lyc Lyα luminosity emitted from a galaxy
outflow + dustmodel
0.8
Lyα LF ( Model vs. Observation )
Lyα Luminosity log[L(Lyα) erg/s]
LAE evolution model (Kobayashi et al.2007)
galaxy evol.
Increase in HI
Num
ber
dens
ity lo
g[n(
>L)
Mpc
-3]
TLyα z=6.6: 0.62–0.78 IGM
TLyα=1IGM
Lyα LF ( Model vs. Observation )
Lyα Luminosity log[L(Lyα) erg/s]
LAE evolution model (Kobayashi et al.2007)
galaxy evol.
Num
ber
dens
ity lo
g[n(
>L)
Mpc
-3]
TLyα z=7.0: 0.40–0.64IGM
TLyα=1IGM
Increase in HI
Lyα line attenuation: Model of Santos ( 2004 )
Neutral Fractionwavelength(A)
Flu
xIGM transmission to Lyα photons: TLyα
z=6.6: 0.62–0.78 z=7.0: 0.40–0.64
Neutral Fraction z=6.6 24–36% z=7.0 32–64%
TL
yα
IGM
IGM
z=5.7
z=6.5
z=7
Ota 08Kashikawa 06
Shimasaku 06 Ouchi 08
van Breukelen 05
Dawson 07
Gal. evol.
z~3-5
Model predictionKobayashi 07
reionization
Fan et al.2006 ARAARedshift z
Reionization HistoryN
eutr
al F
ract
ion
XH
I
z=7z=6.6Lyα Emitters
ConclusionConclusion
When did reionizationWhen did reionization end?end?
NOTE:NOTE:• Estimation of XEstimation of XHIHI is model dependent. is model dependent.• z=7 LAE survey is shallow.z=7 LAE survey is shallow.• We surveyed only one sky field.We surveyed only one sky field.
LAEs support late reionization.LAEs support late reionization.Reionization might have ended at Reionization might have ended at
z~6.z~6.
OutlineOutline
I. Goal: to address the question,I. Goal: to address the question,
When did reionizationWhen did reionization complete?complete?
II. Approach: LyαII. Approach: Lyα Emitters Emitters
III. ResultIII. Result
IV. ConclusionIV. Conclusion
V. Upcoming ProjectsV. Upcoming Projects
NB1005 filterNB1005 filter z~7.3 LAE z~7.3 LAE center=10050Acenter=10050AFWHM=210AFWHM=210A
Upcoming ProjectsUpcoming ProjectsNew Filter + New CCDsNew Filter + New CCDs
Fil
ter
Res
po
nse
Wavelength (A)
Red-sensitive CCDs Red-sensitive CCDs for Suprime-Camfor Suprime-CamQEQE @ 1μm ~ 0.422@ 1μm ~ 0.422
34’x27’ Suprime-Cam
NB1005
Upcoming Project (1)Upcoming Project (1)
Subaru Deep Field
Deepen z=7 ImageNB973=24.9 25.4
876 arcmin2
Suprime-Cam 1 pointing
Improved samples z=7 LAEs z=7.3 LAEs
Obtain z=7.3 ImageNB1005=25.0 or deeper
Upcoming Project (2)Upcoming Project (2)
Samples:z=5.7 LAEs 5 fieldsz=6.6 LAEs 5 fields(Ouchi et al.)
z=7 LAEs 1 fieldz=7 LAEs 1 fieldz=7.3 LAEs 1 fieldz=7.3 LAEs 1 field(Observation in this Oct. & Nov.) (Observation in this Oct. & Nov.)
Subaru/XMM-Newton Deep
Survey ( SXDS )~1.3 degree2
(Suprime-Cam 5 pointings)
UV LF of LAEs at z=5.7 – 7 UV LF of LAEs at z=5.7 – 7