第2回銀河進化研究会 (05/06/15)

z=2.2 Lya輝線銀河のLya輝線とUV連続光の統計的性質
今野彰 (東京大学)
共同研究者：
大内正己、中島王彦、嶋作一大、日下部晴香

本研究の目的
8Faint-end"
slope α"KONNO ET AL .

No. 2, 2008

SUBARU/XMM-NEWTON DEEP SURVEY. IV.
UV LF of LBG@z=3;
Steidel+99"

z=7.3 Lya LF"
Konno+14"z=3.1 UV LF; Ouchi+08"

Fig. 22.—UV luminosity functions ( LFs) of LAEs at z ¼ 3:1 5:7 The cyan, blue, and red circles indicate the best estimates of LFs for our z ¼ 3:1 (top), 3.7 (mi5.7 (bottom) LAEs. The solid lines represent the best-fit Schechter functions for the best estimates. The best-fit Schechter function of z ¼ 3:1 LAEs is presented in efor reference. The triangles are the lower limits of these LFs at each redshift that are derived with the aperture photometry of broadband images (see text). For ctriangles, we show the reliable and less reliable measurements with filled and open symbols, which are obtained with UV magnitudes at >5 " and 2–5 " levels, respec
only use these >5 " data ( filled circles) for our Schechter-function fit (see text). The filled squares and stars in the bottom panel are the UV LFs of LAEs at z ¼ 5:7 obFigure 8. Comparison of our z = 7.3 Lyα LF with the previous measureFigure 7. Lyα LF of our z = 7.3 LAEs. The red filled circles
represent
Shimasaku et al. (2006) and Hu & Cowie (2006). In each panel, we also plot the UV LFs of dropout galaxies for comparison. The dashed and dot-dashed lines are the zofrespectively.
Lyα LFz =7.3 ±the0.4.
Thered etcircles= 7.3
the Lyα LF derived with the data of the entire fields, i.e. both
theLF iszmultipliedby 1/10. No
of Steidel
et al.SXDS(1999) and ( Paltani ments
et al. 2006),
Theat
dottedline indicatesz ¼ 3 LF
of Steidelal. (1999),denotebut ## of theour
LF ofz ¼ Lyα
4 dropoutgalaxies are almost
as that¼ 3red(Steidelet al. 1999;
Ouchi
et al. 2004a;
Beckwith et al.
2006; Yoshida
et al. 2006).
In thediabottom panel
LyαsameLF,
andof zthe
curve
is thebest-fit
Schechter
function.
Theorangeand COSMOS fields. The red open circles and squares denote
ourLFsthe UV LFs of dropout galaxies at z ! 6 with crosses ( Bouwens et al. 2006) and asterisks (Shimasaku et al. 2006). The gray region in the bottom panel indicates the ramonds,square,
andtriangles
represent
Subaruof theet Lyαestimated with the data of the SXDS and COSMOS fields, respectively.
In for i-dropouts
best-fit Schechter functions
obtainedby various
studies( Bunker et al.
2004; Yan &theWindhorst
2004; measurements
Malhotra et al. 2005; Bouwensal. 2006), whichz =LF.7.0−reader’s
7.3 given
byweShibuya
al.obtained(2012),
et onal.the(2006),
andaxis.
measurements
forLF
z ¼ 6atdropout
For theeye guide,plot ticks ofet
SFR
from Iyeeq. (10)upper abscissa
the brightest luminosity bin, we also plot the upper error of uncertainties
the LyαofLF
in• Open questions :"– Lya LF の暗い側の傾き!？
Ota et al. (2010), respectively. The gray region indicates the parameter space
COSMOS field. The best-fit Schechter function for the Lyα LF of the entireof z = 7.7 Lyα (e.g.
LF ruled outUV
by the VLTobservations(Clément et al. 2012).
fieldsisshownwiththeredcurve.
– z<3 LAE の UV/Lya EW の統計的性質
LF& EW分布)？
The black dashed line is the upper limit of the number density determined by
the VLT photometric observations, while the black solid line represents theof the faint-end LF. Because the luminosity range of ourupper limits from the combination of the VLT photometric and spectroscopic– isLAEとtheLBG/AGNLF
not wide,parameter of α in との関係？
the Schechter funcdata (Clément et al. 2012). The cyan filled pentagons, hexagons, and crosses

with the NB816 band overestimate the broadband magnitudes,
In Figure 22 we find that UV LFs of LAEs do not chFig. 22.—UV
functionsLFs)narrowof LAEs atband
z ¼ 3:1
5:7 The cyan,
blue, and red z
circlesthe bestestimatesof LFs
z ¼5.7.
3:1 (top),
3.7 (middle),
4, butevolvefromz for! our4 toThereexistsandanbecause
the Ly!luminosity
morphology
in(theis generally
more’ 3indicate
5.7 (bottom) LAEs. The solid lines represent the best-fit Schechter functions for the best estimates. The best-fit Schechter function of z ¼ 3:1 LAEs is presented in each pane
genceofUV-brightLAEs
atz¼
5:7.
We
comparetheseextended
thanUVmorphology
onthebroadband.
Thus,
wetakefor reference. The triangles are the lower limits of these LFs at each redshift that are derived with the aperture photometry of broadband images (see text). For circles
andU_AUTO magnitudes
we show the reliable
reliablewith filled andopen thesymbols, which
are thoseobtainedofwithUV magnitudes
at >5 "At
andz2–5respectively.
We4, numberdenwith
dropout
galaxies.
¼ "3levels,
ourtriangles,
best estimates
basedand
onlessthe
MAGmeasurements
withonly usethese >5 " datafor our Schechter-function
fit (see text). The filled squares
andLAEs
stars in are
the bottom
panel asare 10%the UVof
LFsthoseof LAEs
z ¼ 5:7 obtainedby
ouras muchofatdropout
galaxiesourcedeblendingon( filledthe circles)
broadband
images.

et al. (2006) and Hu & Cowie (2006). In each panel, we also plot the UV LFs of dropout galaxies for comparison. The dashed and dot-dashed lines are the z ¼ 3 LFs
tion cannot be determined. We fix a power-lawShimasaku
slope
ofand ( Paltanidenote
4m-telescope
estimates
theLyαLF atz of=the LF
7.7
obtained
is multipliedby 1/10.by
Note that theof Steidel
et al. (1999)
et al. 2006),therespectively.
The dotted line indicatesthe z ¼ 3of
LF ofSteidel
et al. (1999),but #LF of z ¼ 4 dropout galaxies are almost same as that of z ¼ 3 (Steidel et al. 1999; Ouchi et al. 2004a; Beckwith et al. 2006; Yoshida et al. 2006). In the bottom panel, we show
Hibon et al. (2010), Krug et al. (2012), and Tilvi et al. (2010), respectively.
α = −1.5, which is a fiducial value used for low-zthe UV
Lyα
LFs of LFs
dropout galaxies at z ! 6 with crosses ( Bouwens et al. 2006) and asterisks (Shimasaku et al. 2006). The gray region in the bottom panel indicates the range of theThe obtained
cyan byopenandhexagons
are2004;
theMalhotra
sameetas
theBouwens
cyan etfilled
penbest-fit Schechter functions for i-dropoutsvariouspentagons
studies ( Bunker etal. 2004;
Yan & Windhorst
al. 2005;
al. 2006),
which show the(e.g., Malhotra & Rhoads 2004; Kashikawa et al. 2006,2011;
uncertainties
of measurements fortagons
z ¼ 6 dropout
For the reader’s but
eye guide,ticks of SFR
from eq. (10) on thedetection
upper abscissa axis.
andLF.hexagons,
for wetheplotresults
ofobtained
no emission-lineof the2Ouchi et al. 2008, 2010). In the calculations for the χ valspectroscopic follow-up observations for the 4m-telescope samples, whichwith theNB816 band overestimate
the broadband
magnitudes,
In Figure
22 we findthat(2014),
UV LFs respectively.
of LAEs do not change atues, we adopt an upper error as 1σ in the case thatmodelsare presented
in Clément
et al. (2012)
and Faisst
et al.
because the Ly! morphology in the narrow band is generally morez ’ 3 4, but evolve from z ! 4 to 5.7. There exists an emerare beyond the data point of our LF. Similarly, a lowererror#• 大規模 & 幅広いLya光度範囲の z=2.2 LAE サンプルを用いて、LAEの統計的性質を探る

z=2.2 LAE サンプル
Selection"criteria"– PI: 大内, 観測解析: 中島・嶋作– 4天域, 計~1.4平方度• COSMOS, SXDS, GOODS, SSA22"– UV/X線/電波 catalog を用いてAGN や他の emitter を除去– ~3400天体 (Nakajima+)"

B - NB387!

• Suprime-Cam NB387 obs."• Lya EW homogeneous な LAEサンプル

Model LAE"
(EW=30,60,100,200A)"
Elliptical, Spiral"Starburst, Galactic star "U - NB387!

– EW=30, 60A の 2つのLAEサンプルを用意– EW=30(60)A のサンプルに対し、~2200(~1000)天体• 過去の研究: 数十 ‒ 数百天体 (e.g. Blanc+11, Cassata+11)"– Lya 限界光度 … log L(Lya) ~ 41.8 erg/s (~0.1L*(z=3-6))!

• 大規模 & 幅広いLya光度範囲の z=2 LAE サンプルを構築

結果 – Lya LF 	Blanc+11"
Cassata+11"This Work!

Ciardullo+11,14"

Hayes+10"

結果 – Lya LF	
Blanc+11"
Cassata+11"
Hayes+10"

This Work!

個数密度超過!

Ciardullo+11,14"• EW=30Aサンプルを利用、過去の研究と一致"• Schechter 関数フィット"
42*+2.45"4"3" ! = !1.71+0.12 L* = 4.74+1.30"10erg/s!
=5.73
#10
Mpc
!0.91
"1.93
!0.11"• 同時フィットでの強い制限は本研究が初めて"

結果 – z=2.2-3.1でのLya LF進化
z=3.1"

Inner : 68% CL"
Outer : 90% CL"

z=3.1"(Ouchi+08)"

z=2.2"(This Work)"増加

z=2.2"• EW=60Aサンプルを利用 (c.f. EW~64A for z=3.1; Ouchi+08)"• z=2.2から3.1にかけてLya LFは >90% 信頼度で増加"– 過去の研究と一致 (e.g. Ciardullo+11)"

結果 – Lya 光度密度進化
This!
Work!

• 全ての z で同じLya限界光度まで積分 (log L(Lya) = 42.4)"• z=7で加速的進化 (Konno+14)"• z<3で急激に減少 → Lya 脱出率の急激な変化"– 原因：ダスト、中性水素柱密度の増加の可能性"

結果 – UV LFとその進化
z=3.1"(Ouchi+08)"

z=2.2"(This Work)"

z=3.1"
z=2.2"
Inner : 68% CL"
Outer : 90% CL"• z=2 での Lya fraction と整合 (EW=30(60)Aで13(4)%; Cassata+15)"• z=2.2-3.1 で UV LF は有意な進化が見られず (or 増加？)"– z=3.1 UV LF のエラーが大きいため"• LBG UV LF は z>2 で単調減少 (e.g. Reddy & Steidel 09 & Bouwens+14)"– LAE UV LF は z=2-4 で大きく進化せず、z=5 で増加 (Ouchi+08)"– z=2 から high-z で LAE が単調に優勢になる描像"

結果 – Lya EW分布とその進化
z=3.1"(Ouchi+08)"

z=2.2"(This Work)"

z=2.2 (total)"• Exp. fit → scale length = 72.0(+4.1)(-4.0) A"– 過去の研究と一致 (83(+10)(-10)A at z=2.1; Guaita+10)"• 同じ EW & L(Lya) cut で z=3.1 との比較	
– z=2.2-3.1で分布は大きく進化していない。"– large Lya EW (EW > 240A) 天体の割合 … 23% at z=2.2"– 10 – 40% at z=3-6 (Ouchi+08) → どの時期でも同じ割合。"

結果 – UV slopeとLya/UV関係
赤UV slope"

UV slope"

赤Kurcznski+14!
LBGs at 2<z<3!
青青明UV mag"

暗暗log L(Lya)"ame UV continuum is characterized by according• 定義to: " fλ ∝ λβ ; β = −2 corresponds
ctrum
in fνと同様の傾向. Local starburst
galaxies• LBGs(cf. beta= -1.8have… Hathi+13)"
as an extremely blue example, NGC 4861
• Lya が強いほど
UVTheslopeが小さくなる(青くなる)"
4 (Meureret al. 1999).
lowestexpected– ダストによる影響の可能性
3, corresponds
to the spectrum of individual明議論 – Lya LF の faint/bright end
受からない領域"

w/o X-ray, radio"w/ X-ray, radio"

UV mag"暗"個数密度超過が"抑えられる"明"暗"log L(Lya)"明"• LAE Lya LF (z=2.2; This Work) … "! = !1.71
一致する理由？	
• LBG UV LF (z=2; Reddy+09) … "! = !1.73– UV-Lya conversion factor 一定？？"• bright end での個数密度超過 AGNの寄与がほとんど"

結果とまとめ	• 大規模 & 幅広いLya光度範囲の z=2.2 LAE サンプルを用いて、LAEの統計的性質を探った"+0.12• Lya LF faint-end slope を仮定無しに制限; " ! = !1.71!0.11– 同時フィットで強い制限は本研究が初めて"– UV LF of z=2 LBG のとほぼ同じ"– 明るい側で個数密度超過 → AGN による寄与"• z=2.2-3.1 で Lya LF は有意に進化しているが、UV LF は有意に進化せず。"• Lya EW 分布は z=2.2-3.1 で同じ分布"– large EW 天体の割合は z=2-6 までほぼ一定 (10-40%)"• UV slope は Lya/UVと相関がある？(不定性大)"