The Build-up of the Red Sequence at z

The Build-up of the Red Sequence at z<1.3

Masayuki Tanaka (ESO, not STScI)

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Taddy Kodama (NAOJ)

galaxies come in two flavours...red

blue

bright faint

Conclusion

• The bright end of the red sequence appears first and it extends to fainter mags., and the build-up of the red sequence is ‘delayed’ in low density environments.

• Galaxy-galaxy interactions may be a primary driver of this build-up.E

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Outline of this talk

0 – Introduction

1 – PISCES project

2 – Large-scale structures around distant clusters

3 – Build-up of the red sequence at z<1.3

4 – Spectral Diagnostics

5 – Summary

large-scale structure in the local

universe

0 – Introduction

outline

0 – introduction

1 – pisces prject

2 – large-scale structures in the distant

universe

3 – the build-up of the colour-magnitude

relation

4 – spectral diagnostics

5 – summary

Galaxies in low-density

environments...

NGC5668

Galaxies in high-density

environments...

Coma

cluster

Clusters at higher redshifts

CL0016 at z=0.55 taken with WFPC2 on

HST

?

?

?

?

?

Clusters at higher redshifts

CL0016 at z=0.55 taken with WFPC2 on

HST

Cluster outskirts and surrounding

clumps/filaments remain unexplored.

Also, faint galaxies at high redshifts have not

been extensively examined yet.

We carried out a wide and deep cluster

survey.

1 – PISCES projectoutline

1 – pisces project

2 – large-scale structures around distant

clusters

3 – the build-up of the red sequence

4 – spectral diagnostics

5 – summary

Pi·sces   [pahy-seez, pis-eez]

-n.   1. A constellation in the equatorial region of the Northern Hemisphere

near Aries and Pegasus. Also called Fishes.

2. a. The 12th sign of the zodiac in astrology. Also called Fishes.

b. pl. Pisces One who is born under this sign.

3. A deep, wide-field survey of galaxy clusters at 0.4<z<1.3.

PISCES project (in A&A abstract format)

For details, see Kodama+ 2005 PASJ, 57, 309

Aims:

Methods:

Results:

Conclusions:

Our goal is to quantify galaxy properties as functions of

environment, mass, and time and understand how and when the

environmental dependence of galaxy properties is established.

We carry out a systematic, deep (~M*+4), wide-field (30’x30’),

optical-nearIR imaging + spectroscopic survey of distant clusters.

Some of our recent results are presented in this talk.

Our survey is not finished yet, so…..we will see.

ACS/

HST

CL0016+16 at z=0.55

BVRiz photometry + 150 spec. objects

RXJ1716 at z=0.81

VRizK, H photometry + AKARI IR photometry

RXJ0152-13 at z=0.83

VRizK photometry + 200 spec. objects

RDCSJ0910 at z=1.1

VRizK photometry + some spec. objects

RDCSJ1252 at z=1.24

VRizK photometry + some spec. objects

2 – Large-scale structures

around distant clusters

outline

1 – pisces project

2 – large-scale structures around distant

clusters

3 – the build-up of the red sequence

4 – spectral diagnostics

5 – summary

Large-scale structure in the local Universe

~70,700 objects~3,600 objects

0.48<zphot<0.60

Large-Scale Structures at z=0.55

CL0016 at z=0.55 (Tanaka+ MNRAS, 2007, 379, 1546)

~3,600 objects

0.48<zphot<0.60

Large-Scale Structures at z=0.55cluster redshift

CL0016 at z=0.55 (Tanaka+ MNRAS, 2007, 379, 1546)

Large-Scale Structures at z=0.83

RXJ0153 at z=0.83Tanaka+ 2006 MNRAS, 365, 13920.76<zphot<0.88

red galaxies

blue galaxies

Redshift distribution of spec. galaxies

0.76<zphot<0.88

cluster redshift

RXJ0153 at z=0.83Tanaka+ 2006 MNRAS, 365, 1392

RXJ0153 at z=0.83

Large-Scale Structures at z=0.83

z=0.844

z=0.842

z=0.745z=0.782

z=0.835

z=0.837

z=0.839

z=0.844

spec. objects at

0.82<z<0.85

0.76<zphot<0.88

Large-Scale Structures at z=1.1

RDCSJ0910 at z=1.1

RDCSJ1252 at z=1.24

Tanaka+ 2007a MNRAS, 377, 1206

Large-Scale Structures at z=1.2

1.17<zphot<1.31

Close-up views of the clumps

3 – Build-up of the red sequenceoutline

1 – pisces project

2 – large-scale structures around distant

clusters

3 – the build-up of the red sequence

4 – spectral diagnostics

5 – summary

galaxies come in two flavours...red

blue

bright faint

Cluster / Group / Field Environments

For details of the definition, refer to Tanaka+2005 MNRAS

Colour-Magnitude Diagrams at z<0.83

blue

red

faintbright

Tanaka+ 2005 MNRAS, 362, 268

Evolution of Fraction of red galaxies

Color-Magnitude Diagrams at z=0.81

RXJ1716 cluster surrounding field

Koyama et al. 2007 MNRAS submitted.

Colour-Magnitude Diagrams at z=1.1 (preliminary!)

RDCSJ0910 at z=1.1

Colour-Magnitude Diagrams at z=1.2

Main Cluster

Lidman et al. 2004 A&A

Composite Group

Tanaka et al. 2007a MNRAS

18 20 22 24 26

Ks

18 20 22 24

Ks

RDCSJ1252 at z=1.24

Colour-Magnitude Diagrams at z=1.2

Main Cluster

Lidman et al. 2004 A&A

Composite Clump

Tanaka et al. 2007a MNRAS

1 – The bright-end of the red sequence appears first

and the faint end appears later.

2 – The build-up of the red sequence is ‘delayed’

in low-density environments.

4 – Spectral Diagnosticsoutline

1 – pisces project

2 – large-scale structures around distant

clusters

3 – the build-up of the red sequence

4 – spectral diagnostics

5 – summary

z=1.24

z=1.1

z=0.83

z=0.81

z=0.55

z=0

: RDCSJ1252

: RDCSJ0910

: RXJ0152

: RXJ1716

: CL0016

: Sloan Survey

composite spectra of red galaxies at z~0.8

composite spectra of red galaxies at z~0.5

composite spectra of red galaxies at z=0

Spectral Diagnostics

...for details see Tanaka+07 MNRAS, 379, 1546

Spectral Diagnostics

Redshift Field Group Cluster z~0.8

z~0.5

z~0

No clear CMR CMR at bright end Tight CMR

CMR at bright end Tight CMR Tight CMR

Red galaxies are consistent with passive evolution

no [OII], no strong Hd

EW[OII]=14A EW[OII]=4A No [OII]

EW[OII]=4A No [OII] No [OII]

No strong Hd Strong Hd No strong Hd

Strong Hd No strong Hd No strong Hd

The strong Hd is suggestive of a sharp decline in star formation rates.

Fast Facts of Environmental Mechanisms

galaxy-galaxy interactions <<1Gyr field/group

harassment ? cluster

ram-pressure stripping <<1Gyr cluster

strangulation ~1Gyr group/cluster

mechanisms star formation effective env.

Fast Facts of Environmental Mechanisms

galaxy-galaxy interactions <<1Gyr field/group

harassment ? cluster

ram-pressure stripping <<1Gyr cluster

strangulation ~1Gyr group/cluster

mechanisms star formation effective env.

For more detailed discussions, see Tanaka+ 2007 MNRAS, 379, 1546

5 – Summaryoutline

1 – pisces project

2 – large-scale structures around distant

clusters

3 – the build-up of the red sequence

4 – spectral diagnostics

5 – summary

Ein Prosit, ein Prosit der Gemütlichkeit!

Ein Prosit, ein Prosit der Gemütlichkeit!

Summary

Galaxies follow the 'environment-dependent down-sizing' evolution.

Galaxy-galaxy interactions may be the driving process of this

evolution.E

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