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Galaxy Formation in a Protocluster at z=3.1
Toru Yamada Tohoku University
Yuichi Matsuda (NAOJ), Tomoki Hayashino (Tohoku) Mariko Kubo (Tohoku) and SSA22 S-Cam/MOIRCS colleagues
a brief general introduction to “protoclusters”
~80-90% are E/S0 galaxies
Coma cluster
● Very old stellar population ● Little star formation now Stars in Galaxies formed at high redshift (z>2-3) - epoch of star formation - epoch of mass assembly
Clusters of Galaxies at present
200Mpc (comoving)
a protocluster
Large-scale distribution of Lyα Emitters
Redshift 3.1
Depth 60Mpc
My talk today
De Lapparent et al. 1988
Void
Coma Cluster
Filaments and walls
Density fluctuation is detected at the epoch of cosmic recombination
WMAP Seven Years Map
http://map.gsfc.nasa.gov/media/101080/index.html
δT / T =O(10-5)
Sloan Digital Sky Survey
CfA Survey depth
Zehavi et al. (2002)
Large Scale Small Scale
500Mpc 30Mpc 1pc =3.26 light years
Z=18.3 13.5 Gyr ago
Z=5.7 12.7 Gyr ago
Z=1.4 9 Gyr ago
~Present 0.1 Gyr ago
Millenium Simulation http://www.mpa-garching.mpg.de/millennium/
Galaxies are “biased” population (biased from the “mass” distribution)
Linear (r.m.s.) bias parameter
14 Mpc
simulation
Weinberg et al. (2004)
b~1 for L* (typical) galaxies at z=0
Mass Galaxies
σ : dispersion of density fluctuation
Cold Dark Matter universe - The early density fluctuation has Gaussian property (any non-Gaussianity??) - Random Phase
Wave Numbers k Scale dependence of the dispersion Power Spectrum (in Fourier space) Power spectrum of
the present-day galaxies
Small scale
Large scale
BAO 0 δ
ρ
ρ’ λ
For a scale λ=2π/k
σ
overdensity
Dark Matter (Mass) Galaxies
Most-massive objects
z=3
z=1
“Bias” at different redshift SPH simulation by Weinberg et al. (2004)
Galaxies
Dark Matter (Mass)
What are the expected consequence of Biased galaxy formation?
● High-redshift galaxies show the clustering as strong as the present-day galaxies ● Statistically, galaxies in the dense region (cluster) are older, more massive galaxies are older ● Clustering strength of galaxies represent typical DMH mass associated with the galaxies (assuming “halo occupation” of the galaxies) ● Galaxy formation preferentially occur in the high-redshift high-density region
Kajisawa, ,TY, et al. 2010 Subaru MOIRCS Deep Survey
Evolution of the Stellar Mass Density Evolution In the Universe
high-z protocluster ○ Overdensity of Lyman Break galaxies、Lyman α emitters z=2-6 e.g., Adelberger et al. 1998 ○ Overdensity around powerful radio galaxies z=2-4 e.g., Venemans et al. 2006, Kodama et al. 2007, Tanaka et al. 2011, Mahalo-Subaru, etc. ○ X-ray selected clusters z
Galaxy Formation in a Protocluster at z=3.1
Hayashino et al. 2004, AJ, 129, 2073 Matsuda et al. 2004, AJ, 128, 569 Geach et al. 2005, MNRAS, 363, 1398 Matsuda et al. 2005, ApJ, 63, L125 Matsuda et al. 2006, ApJ, 640, L123 Matsuda et al. 2007, ApJ, 667, 667 Uchimoto et al. 2008, PASJ, 60, 683 Webb et al. 2009, ApJ, 692, 1561 Lehmer et al. 2009, ApJ, 691, 687 Yamada 2009, New Astronomy, 53, 54 Matsuda et al. 2011, MNRAS, 410,L13 Yamada et al. 2012, AJ, 143, 79 Uchimoto et al. 2012 ApJ, 750,116 Yamada et al. 2012b, ApJ, 751,29 Matsuda et al. 2012, MN, 425, 878 Kubo et al. 2013, ApJ, in press Yamada et al. 2012c, in preparation Kubo et al. 2013, in preparation Otsuka et al. 2014, in preparation
1. “Superstructure” around the SSA22 protocluster traced by the Lyα Emitters
SSA22 region (22h16m, 0d15m) ● Discovered as a rdshift peak of Lyman Break Galaxies at z=3.1 6x number density of the average in ~20x15x21Mpc3 (comoving) (Steidel et al. 1998; Adelberger et al. 1998; Steidel et al. 2000; 2003) ● one of the most prominent structure at z~3 discovered so far
z=3.1 redshift peak
LBG redshift distribution in 6 obserrved fields Redshift z
10’x15’
Lyman Break Galaxies = UV bright galaxies
Color “drop out” caused by the attenuation by neutral hydrogen (HI) in Intergalactic medium (IGM)
B V
NB497
LAE: Lyman α Emitters
Star-forming galaxies
BV
Observing Lyα Emitters by Narrow-Band Imaging
中村 2007、修論
LAE, LAA, LAB
Y.Nakamura, master thesis
Narrow-band Search for Lyα Emitters
静止系(放射)波長 [μm]
相対的光度
相対的光度
近傍銀河のスペクトル(比較のため)
楕円銀河
Scd 円盤銀河
マゼラン型 不規則銀河
Sbc 円盤銀河
楕円銀河
Scd 円盤銀河
マゼラン型 不規則銀河
Sbc 円盤銀河
Spectra of High-redshift galaxies
flux
wavelength
Lyman Break galaxies
Distant Red Galaxies
主鏡口径8.2m 単一鏡 世界最大級
Subaru Telescope 昴望遠鏡 (国立天文台)
建設 9年 (1992-2000 年) ハワイ島 マウナケア山頂 標高4200m
Early results (2004): Subaru/Suprime Cam 1Field of View
LAE average local density
Hayashino et al. 2004 Steidel et al. 2000
LAB2 LAB1
NB width ~60 Mpc
● Lyα Emitters (LAE) ● Lyα Absorbers (LAA)
25” or 190 kpc at z = 3.1
35 Lyα Blobs at z=3.1 in SSA22-Sb1 (Matsuda et al. 2004)
First large (>10) sample of LABs
Prototypical Giant Lyα Blobs d~30-150kpc, L~10+42-44 erg/s, δv ~ 500-2000 km/s
25” = 190 kpc @ z=3.1
Steidel et al. 2000 SSA22 Blob1 Keel et al. 1999 53W002 field No.18
SCUBA source Obscured AGN (narrow-line, low excitation)
10” = 80 kpc @ z=2.4
Both Subaru Images (Matsuda+04,07, Mawatari et al. 2012, in preparation)
Sub-mm emission was reported, but not confirmed No sign of AGN
Seven Suprime Cam Fields (to the similar depth)
+ 5 General Fields (GOODSN, SDF, SXDS-N,-C,-S) with same quality
200Mpc (comoving)
Highest contour =5.5xaverage
Large-scale distribution of ~1500 Lyα Emitters NB width ~60 Mpc
De Lapparent et al. 1988
Void
Coma Cluster
Filaments and walls
(control) general fields to be compared
SXDS / UDS
GOODS-N
SDF
Overdensity of SSA22 High Density Region
Yamada et al. 2012
Average density in General Fields = 0.20/arcmin2
Sb1 34’x27’ ~60Mpc 0.43 /arcmin2
Q. How significant is the overdensity?
200Mpc (comoving)
Large-scale distribution of ~1500 Lyα Emitters
Sb1
peak
Comparison with CDM linear theory
If LAEs trace mass with the (linear) bias b ~ 2 (Gawiser et al. 2007)
still it corresponds to ~5 σLAE (Gaussian probability ~10-6 ) ~O(1) such structure is expected within ~100Gpc3
δ(LAE) = δN/N0 (LAE) ~ δρ/ρ (LAE)
~60x40x60Mpc (comoving)
10x σmass
Expected from CDM
The overdensity at SSA22 Sb1 3.6-4.5 σ(LAE) @ ~60Mpc comoving scale
No equivalently high-density region is found In the Millennium Simulation
700arcmin2~Sb1 100arcmin2 ~density peak
Comparison with Millennium Simulation ‘false LAE’ samples
● Clear identification of the protocluster and surrounding structure with filaments and voids ● Very large density enhancement in large scale Sb1 ~5σLAE (CDM+b=2), ~3.5-4.5σLAE(Millennium) whole Sb1-Sb7 ~2.5σLAE a proto-Great Wall ● Very rare in Gaussian probability distribution ● More than ‘simple halo bias’ for Lyα Emitters Emission Line Bias (Origin of emission lines?)
2. Mass assembly and galaxy formation in the SSA22 protocluster
200Mpc (comoving)
Stellar Massive galaxies
Protocluster “Core”
Subaru/MOIRCS NIR Observations K < 24 (AB) Photo-z 2.6-3.6
The area observed with MOIRCS
Surface Number Density excess of the SSA22 MOIRCS survey field
SSA22 whole MOIRCS field
GOODS
overdensity at the “peak”
GOODS
K
静止系(放射)波長 [μm]
相対的光度
相対的光度
近傍銀河のスペクトル(比較のため)
楕円銀河
Scd 円盤銀河
マゼラン型 不規則銀河
Sbc 円盤銀河
楕円銀河
Scd 円盤銀河
マゼラン型 不規則銀河
Sbc 円盤銀河
Spectra of High-redshift galaxies
flux
wavelength
Lyman Break galaxies
Distant Red Galaxies
Distribution of Massive (>1011Msun) Galaxies
Protocluster Core
Little overlap with LBG/LAE
Spectroscopy of the K-band selected galaxies w/MOIRCS (complementary with Lyman Break Galaxies)
Comparison with Coma Cluster Stellar Mass Function
2013/10/24
Properties of the K-band (K
2013/10/25 Protocluster Core Field
Colors of LBGs
Colors of “quiescent” (no star formation) galaxies
Dust Reddening
2013/10/24
For M(stellar) > 1011Msun quiescent galaxies ● ~ 50% of the cluster member are quiescent (i.e., their intensive star formation is halted) ● no counterparts in GOODS-N(MODS) ● clustered at around the peak of LAEs
F160W KMOIRCS
F160W KMOIRCS Two examples of the quiescent galaxies They are compact! (re~2kpc)
F814W F125W
I F125W
2013/10/24
Concentration of “Quiescent” galaxies in the z=3.1 protocluster
LAE peak
2013/10/24
For M(stellar) > 1011Msun dusty red galaxies ● > 20% of the cluster member are dusty startburst (1.8 times surface overdensity) ● diffused morphology
F814W F125W F160W KMOIRCS
F814W F125W F160W KMOIRCS
2013/10/25
Distributions of “Spitzer 24um detected sample” “Chandra X-ray detected sample”
(whole field) 1.9 times of GOODS-N (whole field) 2.5 times of GOODS-N (whole field) 1.9 times of GOODS-N
2013/10/24
Multiple Merging Systems
200Mpc (comoving)
Stellar Massive galaxies
2013/10/24
From Mariko Kubo, TY (2013)
Multiple Merging Galaxies at the protocluster outskirt
20”
2013/10/24
Multiple Merging Galaxies at the protocluster outskirt
From Mariko Kubo, TY, et al.
20”
Origins of the stellar mass that accreted to the galaxies
Massive Galaxies (3x1011)
Less Massive Galaxies (5x1010)
Low mass
intermediate
Massive
Stars formed outside the virial radius accreted
age and radius
Oser et al. 2010 Two-Phase Galaxy Formation
No feedback
Age
Log R/Rvir
Rvir
Summary (1)
Using Subaru Telescope and its instruments (Suprime Cam, MOIRCS), we revealed the population of galaxies in the well characterized very rich Protocluster at z=3.1 (11.5 Gyr ago). ● New ~2deg2 narrow-band Lyα Survey z=3.1 SSA22 protocluster ● Characterizing the significance of the cluster Very high significance 4-5σLAE@50Mpc scale Large overdensity over large scale
Summary (2) ● Mass assembly in the protocluster: witnessing massive galaxy formation in cluster ● A significant fraction (50% for Mstr>10^11Msun) of quiescent galaxies ● another significant fraction (>20%) are extremely dusty red galaxies with intense star formation ● Multiple Merging Systems: site of massive GF
If I have more time…..
● Lyα Equivalent Width Distribution ● Diffuse Lyα Halos ● Lyα Blobs
Lyα Equivalent Width
flux
equal area
Equivalent width
For Lyα, If photoionization; Ionizing UV photons
Non-ionizing UV photons
Malhotra et sl. 2002; Charlot and Fall 1993
Case of Photoionization:Lyα EW and IMF
Continuous Constant SFR 1/20 metallicity Model A Salpeter IMF x=2.35 Model B Top heavy IMF x=0.5 Ml=1 Msun Mu=120 Msun
~240Å
EW0 > 240 Å POPIII ? If constant continuous SFH
Lyα (rest Frame, mean-IGM corrected) Cumulative Equivalent Width Distribution
EW Lower limit
Lyα (rest Frame, mean-IGM corrected) Equivalent Width Distribution ● Large number of large EW > 200Åobjects (> 30% if EW is measured in NB Kron aperture) Large EW Young, Metal poor population for the photoionization models Other process (heating by outflow, or cold stream) ● Large fraction of large EW objects in SSA22 high-density region if the high density region is more biased to the aged population, large EW is not due to the young/metal-poor population
Lyα EW and local surface density
SSA22 fields
General Fields
High
Medium
Low
EW does not depend on local surface density
σ=1.5’ Gaussian Kernel smoothing
● Lyα Emitters ○ Lyα Blobs ● Lyα Absorbers
Lyα Blobs in the new survey
Comparison of the number density of LABs
c.f. Overdensity in entire LAEs at SSA22 protoCluster (Sb1) δρ/ρ(LAEs) [Sb1] ~ 1.5
>100kpc LAB (Matsuda et al. 2011)
More ‘filamentary’ LABs In LAE low density regions cold Accretion ?
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