最近の z~7-8 LBG 探査 2009 年 10 月 28 日 鍛治澤 賢

最近の z~7-8 LBG 探査の論文紹介 HUDF: HST/WFC3 HUDF: HST/WFC3 GOODS-S: HST/WFC3 GOODS-S: HST/WFC3 GOODS-S: VLT/HAWK-I GOODS-S: VLT/HAWK-I SDF & GOODS-N: Subaru/Suprime-Cam SDF & GOODS-N: Subaru/Suprime-Cam COSMOS: UKIRT/WFCAM & CFHT/WIRCAM COSMOS: UKIRT/WFCAM & CFHT/WIRCAM Bouwens et al arXiv: Y-dropout UVLF Oesch et al arXiv: z-dropout UVLF Bunker et al arXiv: z-dropout UVLF McLure et al arXiv: photo-z SED fitting Labbe et al arXiv: IRAC stellar mass Oesch et al arXiv: morphology Wilkins et al arXiv: z-dropout Castellano et al arXiv: z-dropout Hickey et al arXiv: Y&z-dropout Ouchi et al arXiv: z-dropout Capak et al arXiv: z-dropout

Lyman break feature Lyman break

z=0.5z=1.0 z=1.5 z=3.0

Lyman Break Galaxies U-dropout z~3 G-dropout z~4

Previous studies of z~7 LBGs Bouwens et al HST/NICMOS J&H-bands data limiting mag. ~ ABmag

最近の z~7-8 LBG 探査の論文紹介 HUDF: HST/WFC3 HUDF: HST/WFC3 GOODS-S: HST/WFC3 GOODS-S: HST/WFC3 GOODS-S: VLT/HAWK-I GOODS-S: VLT/HAWK-I SDF & GOODS-N: Subaru/Suprime-Cam SDF & GOODS-N: Subaru/Suprime-Cam COSMOS: UKIRT/WFCAM & CFHT/WIRCAM COSMOS: UKIRT/WFCAM & CFHT/WIRCAM Bouwens et al arXiv: Y-dropout UVLF Oesch et al arXiv: z-dropout UVLF Bunker et al arXiv: z-dropout UVLF McLure et al arXiv: photo-z SED fitting Labbe et al arXiv: IRAC stellar mass Oesch et al arXiv: morphology Wilkins et al arXiv: z-dropout Castellano et al arXiv: z-dropout Hickey et al arXiv: Y&z-dropout Ouchi et al arXiv: z-dropout Capak et al arXiv: z-dropout

Bouwens et al. arXiv: HUDF HST/WFC3 による Y-dropout 探査 HUDF HST/WFC3 による Y-dropout 探査 Hubble Ultra Deep FieldHST/ACS z-band image HST/NICMOS J&H-bands HST/WFC3 Y, J, H-bands VLT/ISAAC Magellan/PANIC Ks-band Ultra deep HST/ACS optical images McLure et al.

HST/WFC3 WFC3 instrumental handbook

HST/WFC3

Bouwens et al. arXiv: HST/WFC3 data HST/WFC3 data F105W （ Y ） orbits F125W （ J ） orbits F160W （ H ） orbits HUDF09 program first epoch data (two UDF05 fields will be also observed in 2010) PSF FWHM ~ 0.2” 5σ 0.4” diameter ~ 29ABmag (1 orbit ~ 40min) HST/ACS data B, V, i, z -bands ~ ABmag (August 26 ~ September 6, 2009) ~ 4.7 arcmin 2

Bouwens et al. arXiv: Y-dropout selection Y-dropout selection Source detection Color selection J + H combined image >5.5σ in J band Y-J > 0.8 J-H < 0.5 J-H < ×(Y-J) no detection (<2σ) in B,V,i,z (those with 1.5~2σ detection in more than one optical band were rejected)

Bouwens et al. arXiv: selected z~8 candnoidates selected z~8 candnoidates 5 candidates blue J-H color (UV slope β<~-2.5) >5σ in J & >4σ in H All WFC3 data were obrained in 12days brown dwarfs are more bluer and rare Simulation with 24.5~26mag objects Possible contaminants  Not spurious objects  Not SNe  Not galactic stars  the expected number of, contaminants by photometric scatter is very small (<~0.2)

Bouwens et al. arXiv: selected z~8 candidates selected z~8 candidates 5 candidates blue J-H color (UV slope β<~-2.5) H~ mag half light radius ~ 0.15” (~0.7h -1 (~PSF)

Bouwens et al. arXiv: Number counts Number counts Expected number for no LF evolution (1+z) -1 size evolution from z~4 UV slope β=-2.5±0.4 are assumed. z~6 i-dropout LF  24 Y-dropouts z~7 z-dropout LF  11 Y-dropouts (~70% statistical error ~35% field-to-field variance) Observed number is lower (~1σ level)

Bouwens et al. arXiv: Evolution of UV LF Evolution of UV LF Extraoplation of UV LF at z<7 to z~8  M * UV ~-19.45, φ * ~0.0011Mpc -3, α~-1.74 good agreement with the observed results Fit M * UV with the observed data φ * ~0.0011Mpc -3, α~-1.74 are assumed M * UV = -19.3±0.3 M * UV = M * UV = Stepwise LF  weak evolution at -19~-18 mag  strong evolution of M* (?)

Bouwens et al. arXiv: SFR density at z~8 SFR density at z~8 Integrate the stepwise UV LF  UV luminosity density unobscured SFR density (and dust correction with those estimated at z~5-6 )

z~6-9 galaxy search with HUDF HST/WFC3 z~6-9 galaxy search with HUDF HST/WFC3 McLure et al. arXiv: HST/WFC3 HST/ACS Spizter/IRAC HST/ACS z-band image HST/NICMOS J&H-bands HST/WFC3 Y, J, H-bands VLT/ISAAC Magellan/PANIC Ks-band McLure et al. Bouwens et al. と同じデータを独立に処理 PSF FWHM ~ 0.15”(Y), 0.16”(J), 0.18”(H) 5σ diameter ~29ABmag 5σ diameter ~29mag (~28mag for z-band) 5σ limit ~25.9(3.6μm) 25.5(4.5μm) 23.3(5.8μm) 22.9(8.0μm)

Sample selection Sample selection McLure et al. arXiv: Source detection Photometric redshift detection in at least one of YJH-bands No detection (2σ) in i-band  300 objects BVizYJH-bands & 4.5μm upper limit χ 2 distribution  z>5.9 candidates Charlot & Bruzal 2007 templates + empirical U-dropout spectra  49 candidates 〇 : z>7 candidates

Sample selection Sample selection McLure et al. arXiv: Photometric redshift Charlot & Bruzual 2007 templates + empirical U-dropout spectra τ=0.1~10Gyr Calzetti extinction Av=0~2mag 1 solar metallicity Salpeter IMF example χ 2 distribution  z>5.9 candidates  49 candidates zYJH

Sample selection Sample selection McLure et al. arXiv: SED magnitude χ 2 distribution  visual check spurious artifact Transient object The brightest candidate  SN or other transient soruce Contamination by T dwarfs  ~0.5 down to z=29ABmag in 4.5arcmin 2 WFC3 field (not detected at all in NICMOS images)

Selected sample Selected sample McLure et al. arXiv: z>6 candidates No detection in i-band  incomplete at 5.9<z<6.25 including 15 out of 16 z-dropouts in Oesch et al. all 5 Y-dropouts in Bouwens et al. The faintest z-dropout candidate in Oesch et al. + additional 15 z>6.25 candidates

extremely high-z sample extremely high-z sample McLure et al. arXiv: z>7 candidates 8 z>7.5 candidates 3 z>8 candidates 〇 : z>7 candidates Including 5 Y-dropouts in Bouwens et al. these 5 have acceptable secondary peak at z~1.6 4 z>7.8 candidates occur in two pairs J~28-29mag

extremely high-z sample extremely high-z sample McLure et al. arXiv: z>7 candidates 8 z>7.5 candidates 3 z>8 candidates Including 5 Y-dropouts in Bouwens et al. these 5 have acceptable secondary peak at z~1.6 4 z>7.8 candidates occur in two pairs J~28-29mag

extremely high-z sample extremely high-z sample McLure et al. arXiv: z>7 candidates 8 z>7.5 candidates 3 z>8 candidates Including 5 Y-dropouts in Bouwens et al. these 5 have acceptable secondary peak at z~1.6 4 z>7.8 candidates occur in two pairs For the faintest candidates (J, H ~29), no detection in optical ACS images is not sufficient to pick up Lyman break exclusively. J~28-29mag

UV luminosity function UV luminosity function McLure et al. arXiv: redshift probability distribution + 1/Vmax method 6.5<z< <z<8.5 z~7 UVLF z~8 UVLF M * 1500 ~ Φ * ~ Mpc -3 α ~ similar shape with z~6 UVLF number density evolution of a factor of ~2.5 from z~6 cannot constrain the shape of UVLF Number density at M1500~-19.5 is a factor of ~2 smaller than at z~7

Castellano et al. arXiv: z-dropout search in GOODS-S with HAWK-I z-dropout search in GOODS-S with HAWK-I Great Observatories Origins Deep Survey - South deep HST/ACS optical images deep Spizter/IRAC MIR images deep VLT/ISAAC NIR images Chandra Spitzer/MIPS

Castellano et al. arXiv: VLT/HAWK-I data VLT/HAWK-I data HAWK-I 7.5’ x 7.5’ F.O.V 0.106”/pix Y-band 2 pointings Science Verification & ESO Large Program GOODS hour 0.514” FWHM GOODS hour 0.489” FWHM ~89.7arcmin 2 ~100% complete at Y~26.2 ~30%compete at Y~26.8 spurious source negligible at Y<26.5 ~10% at Y~26.8 VLT/VIMOS U, R-bands (29.1, 29.5) HST/ACS B, V, i, z-bands(29.0, 29.1,28.6,28.2) VLT/ISAAC J, H, K-bands (26.6,26.2,26.2) 1σ limit Multi-wavelength data

Castellano et al. arXiv: sample selection sample selection Y-selected Y<26.7 Y-J>1.0 ACS z-band HAWK-I Y-band detect z>6.5 Lyα break

Castellano et al. arXiv: sample selection sample selection Y-selected Y<26.7 Y-J>1.0 Y-J<1.5 & Y-K<2.0 detect z>6.5 Lyα break reject old/dusty galaxies at z~1-4

Castellano et al. arXiv: sample selection sample selection Y-selected Y<26.7 Y-J>1.0 Y-J<1.5 & Y-K<2.0 No detection in optical detect z>6.5 Lyα break reject old/dusty galaxies at z~1-4 One of interlopers with z-Y>1 <2σ in all UBVRI-bands <1σ in at least four of UBVRI-bands 139  9 candidates

Castellano et al. arXiv: Simulation for sample selection Simulation for sample selection add artificial objects with Y= at z=5.5-8 (assuming size and LF of z~5.5-6 LBGs)

Castellano et al. arXiv: Selected candidates Selected candidates 9 z~7 candidates 1 known cool dwarf is rejected (relatively red Y-J color) expected contamination  ~3.4 cool dwarfs for 2 HAWK-I F.O.V. another one which is not detected in the deep NICMOS H-band (Y-H<-1) is rejected  7 candidates

Castellano et al. arXiv: B+V+izYJ+H+KF110WF160W3.6μm

Castellano et al. arXiv: Selected candidates Selected candidates stacking of 7 candidates  z phot =6.80

Castellano et al. arXiv: Number Counts Number Counts Observed number counts of z~6.8 LBGs are smaller than predictions from z~6 LFs. (No evolution for UV LF between z~6 and z~6.8)  UV LF seems to evolve between z~6 and z~6.8

Castellano et al. arXiv: UV luminosity function UV luminosity function Assumed UV Luminosity function simulation (source detection, color selection) Expected z-dropout number counts Observed number counts Maximum likelihood Φ* = ×10 -3 Mpc -3 M*(1500 Å ) = ±0.45 assuming α=-1.71

Castellano et al. arXiv: Evolution of UV LF Evolution of UV LF d(logΦ*)/dz = -0.59±0.25 dM*/dz = 0.13±0.51 Evolution between z~6 and z~6.8 Φ* = ×10 -3 Mpc -3 M*(1500 Å ) = ±0.45 assuming α=-1.71 ρ UV = ×10 25 erg/s/Hz/Mpc 3 UV luminosity density  a factor of ~3.5 lower than at z~6 rule out no evolution between z~6 and z~6.8 at 99% confidence level

Ouchi et al. arXiv: z-dropout search in SDF & GOODS-N with Subaru/S-Cam z-dropout search in SDF & GOODS-N with Subaru/S-Cam GOODS-North Subaru Deep Field

Ouchi et al. arXiv: Suprime-Cam data Suprime-Cam data y (z R )-band 2 fields arcmin 2 Subaru Deep Field 26 hours 810 arcmin 2 GOODS-North 33 hours 758 arcmin 2 3σ 1.8” diameter SDF 26.4 ABmag GOODS-N 26.2 ABmag Other bands SDF BVR + z’ GOODS-N UBVR + z’ z-band 3σ limit SDF 27.7 mag GOODS-N 26.9 mag

Ouchi et al. arXiv: Sample selection Sample selection y-selected samaple >4σ limit SDF y<26.1 GOODS-N y<25.9 z’-y > 1.5 no detection in UBVR-bands (<2σ) selection for z>6.5 galaxies possible contamination by cool dwarfs (no selection by Y-J color) <2σ limit SDF 29.4(B), 28.6(V), 28.8(R) GOODS-N 27.3(U), 28.0(B), 26.7(V), 27.0(R)

Ouchi et al. arXiv: Selected candidates Selected candidates GOODS-NSDF 15+7=22 candidates all candidates have y>25.4mag 1 (brightest) candidate  z spec =6.96

Ouchi et al. arXiv: Selected candidates Selected candidates detection completeness

Ouchi et al. arXiv: UV luminosity fobunction UV luminosity fobunction 22 candidates Expected contamination ~1 spurious source ~0.1 transient object ~1 lower-z galaxies with photometric error ~8 L/T-type dwarfs redshift selection function UV luminosity function signifincantly decreases from z~6 at bright magnitude

Ouchi et al. arXiv: UV luminosity function UV luminosity function Subaru/Scam + HST/NICMOS Φ* = ×10 -3 Mpc -3 M* = -19.9±0.7 α = -1.66±1.32 Evolution between z~6 and z~7 at >2σ level The decrease of L* is dominant factor ?

Ouchi et al. arXiv: UV luminosity density UV luminosity density integrating UV LF ×10 26 erg/s/Hz/Mpc ×10 -3 M ◎ /yr/Mpc 3 SFR density evolution of a factor of >10 between z~2-3 and z~7 SFRD decreases even from z~6 to z~7.

Ouchi et al. arXiv: Spatial distribution Spatial distribution strong clustering of z~7 LBGs especially for UV bright LBGs

Summary RedshiftFieldTelescope/ Instrument Area (arcmin 2 ) Limit mag (AB) Number of candidates Y-dropout (z~8) HUDFHST/WFC3~4.7H<29.2~5 z-dropout (z~7) HUDFHST/WFC3~4.7J<29~15 GOODS-SHST/WFC3~20Y<27~6 GOODS-SVLT/HAWK-I~90Y<26.7~7 GOODS-N&SDFSubaru/SCam~1568Y<26~22 (~12) UV luminosity density (LBG number density) z~6 (i-dropout) z~7 (z-dropout) z~8 (Y-dropout) factor of 2~3.5 decrease factor of 2~3 decrease

おまけ

Oesch et al. arXiv: Size evolution Surface SFR density

Labbe et al. arXiv: Stacking analysis with IRAC data Stellar mass of z&Y-dropouts Evolution of stellar mass density