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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