Accelerated Evolution of
Lya LF at z>7
and the Physical Pictures
(arXiv:1404.6066)
Akira Konno (Univ. of Tokyo, ICRR)
Co-Investigators:
M. Ouchi, Y. Ono, K. Shimasaku, T. Shibuya,
H. Furusawa, K. Nakajima, Y. Naito, R. Momose,
S. Yuma and M. Iye
this single line emitter, due to the limited spectral reso
to-noise ratio of LRIS data (< 5σ). We find that othe
no emission line down to the flux limit indicated from t
These candidates are probably objects with a red con
Ouchi+ 10
2 3456!( -!, L1
Shibuya+ 12
z~7.3
(Hibon,Tilvi,
Krug)
z=6.6
?
z~7.3
(Ota,
Shibuya)
z=5.7
@Neutral
( 3-., L!H.,
4*#&!WCG%F
Fraction x(HI)
WCG%F!4, &!>( !( )*;
Introduction
CMB
LAE/
GRB
QSO
Redshift
• Lya LF evolves from z=6.6 or not ?
•
B( N)56a
• PQR1S!TJ U)!)-3N?!4, &!4#&
&( 3-., L!5?N.#+( &!E., 4*#
Sharp or
⇒ z=7.3 LAE survey address
these6LL!45,
issues.&+( !>( 4, 3
• T?V!TH!I
Figure 1: (Left) Evolution of xHI (Ouchi et al. 2010). D
Lyaevolution
damping
absorption
HI in IGM
ofwing
xHI for
the mini,ofsmall,
and large halo cas
solid linepre
sentsthedoublere
ionization
extended
reionization
history
? scenario (Cen
spectrum of theconfirmed z = 7.2 LAEswith a significa
Subaru/S-Cam NB101 Obs.
Konno+ 14
1) NB101 … more sensitive to line emission than NB1006
2) Total exp. time : 106 hrs … Ultra-deep survey
⇒ Detect very faint LAEs at z=7.3
• 5-sigma limiting L(Lya) = 2.4 x 1042 erg/s
… comparable with z=3-6 LAE survey
… ~4x deeper than Subaru z~7.3 survey
z=7.3 LAE sample
2)
• Field … SXDS and COSMOS
(Total
:
~0.5
deg
A
E
L αL
F
z 7
CCELERATED
VOLUTION OF
Y
UMINOSITY
UNCTION AT
• SXDS : 3 LAEs
• COSMOS : 4LAEs
… Total : 7 LAEs
• Expect ~65 LAEs in
case of no evolution
from z=6.6.
Konno+ 14
Figure 4. Snapshots of our z = 7.3 LAE candidates. The size of each image is 6 × 6 . North is up and east is to the left.
candidates in Table 2. The total magnitudes listed in Table 2
are obtained by the aperture-correction technique explained in
sensitivity for a Lyα emission line. Thus, the reason for
detection of SXDS-NB1006-2 is clear, while the reason
Evolution of Lya LF at z=6.6-7.3
Inner : 68% CL
Outer : 90% CL
z=5.7
(Ouchi+ 08)
z=6.6
z=6.6
(Ouchi+ 10)
z=7.3
(This Study)
Konno+ 14
(Ouchi+ 10)
z=7.3
(This Study)
Konno+ 14
• Conclude that Lya LF decrease from z=6.6 to 7.3
at >90% confidence level.
( Shown by previous studies ; e.g. Clement+12 )
Ellis+ 13
Bouwens+14
Ouchi
+08, 10
This
Study
UV luminosity density
Lya luminosity density
Accelerated Evolution of Lya LF
Konno+ 14
arXiv:1404.6066
• Evolution of Lya LF is accelerated at z>7.
• No such rapid decrease of UV LF at z~7, but only for z~8.
• Different from a pure SFR decrease but related to
Lya escape + production and/or cosmic reionization
Imprecations from Lya LF Evolution
• x(HI) = 0.3-0.8
Model A
… consistent with previous studies
• Compare our x(HI) with CMB
results using theoretical models.
• Our x(HI) → Model A & B
… inconsistent with CMB results
• WMAP result → Model C
… x(HI) is higher than Model C
• A tension between our x(HI)
and CMB results ?
o Clumpy HI clouds
(Bolton & Haehnelt 2013)
o Increase of f_esc of LyC
(Dijkstra+ 2014)
Konno+ 14
Model B
Model C
Choudhury+08
models
Summary
• Ultra-deep Subaru/S-Cam NB101 imaging survey
allow us to detect very faint z=7.3 LAEs.
o L(Lya) = 2.4 x 1042 erg/s … comparable with z=3-6 survey
… ~4x deeper than z~7.3 survey
(1) Evolution of Lya LF at z=6.6-7.3 at >90% CL
(2) Accelerated evolution of Lya LF beyond z=7
• There is a tension between our x(HI) = 0.3 - 0.8 and
CMB results ?
o Support new physical pictures
• high-z LAE survey with HSC → PFS, JWST, TMT etc…