Feb/19/2008

A Demography of Galaxiesin Galaxy Clusters

with the Spectro-photometric Density Measurement.

Joo Heon Yoon 윤주헌 Sukyoung Yi 이석영

Yoon et al. 2008 ApJS in press

(astro-ph/0712.1054)

Dept. of Astronomy Yonsei Univ.

Environment Effect

Check individual clusters of galaxies.

Require homogeneous catalogue.

I. Motivation

II. Method

III. Result

J. H. Yoon

K. Schawinski

S. K. Yi

Incompleteness of SpectroscopyI. Motivation

II. Method

III. Result

1. Classical cluster catalogue (e.g. Abell) Based on eye-inspection. Projection effect, time-consuming…

2. Massive database (SDSS, 2dF, …) Systematic Search! Redshift – 3D distribution! (e.g. C4)

Fiber collision!!

Spectroscopy is incomplete!!

In a dense cluster,

fspec. ~ 65%

Incompleteness Problem!!

1. SDSS DR5 spectroscopic and photometric survey galaxies.

2. 0.05 < z < 0.1

3. Volume limited samples, r<17.77, Mr < -20.54

DataI. Motivation

II. Method

III. Result

How do we add galaxies missed by spectroscopic survey?

Galaxies in a cluster have Color-Magnitude Relation.

Cluster Member Selection via CMRI. Motivation

II. Method

III. Result

Cluster Finding with spec.+phot. data

Measure local density of galaxies

where 3σ=1Mpc, and σv = velocity dispersion

2

2

1 1( ) exp

22a

s

r

22

13 3a z

v

r r

For galaxies

with spectra.

For galaxies

without spectra.

Select red-sequence galaxies in CMR2

2

1 1( ) exp

22a

p

r

2

13ar

s p Finding the

Maximum Density Galaxy!!

Finding Galaxy Cluster!!

I. Motivation

II. Method

III. Result

spectro-photometric density

Cluster Finding with spec.+phot. data

From SDSS

I. Motivation

II. Method

III. Result

Yoon, Schawinski, Sheen, Ree, & Yi, 2008 ApJS in Press (astro-ph/0712.1054)

Efficiency of the New Measurement

From SDSS

I. Motivation

II. Method

III. Result

CTIO observation supports our method.

92% of completeness by CTIO obs.

New density

Spec. density

CTIO density

missing

A2670

Our new method.

Minimize the incompleteness.

Galaxy ClassificationI. Motivation

II. Method

III. Result

From SDSS

1. Consider spectroscopic members

2. Visual Inspection- SDSS optical combined images- Self-consistency- fracdev_r

3. Color Classification

4. Non-cluster Galaxies ρ = 0

Color & Luminosity vs. RadiusI. Motivation

II. Method

III. Result

From SDSS

Color & Luminosity

No clustocentric dependence.

I. Motivation

II. Method

III. Result

From SDSS

Color & Luminosity vs. Radius

Color & Morphology

Clustocentric dependence < R200

MDR is intrisic. The morphology-density relation

Stronger in Denser cluster

Why the Brightest Cluster Galaxy?I. Motivation

II. Method

III. Result

From SDSS

von der Linden et al. 2007 : BCG & non-BCG difference

Liu et al. 2007 : Different scaling relations. Quillen et al. 2007 : Star formation in BCGs.

Secondary of environmental effect?

BCGs in simulation Extremely huge Continuously growing BCGs are so special.

The BCGs vs. DensityI. Motivation

II. Method

III. Result

From SDSS

Denser Brighter BCGs

As well as 2nd BCGs & 3rd BCGs

No difference in their density dependence.

I. Motivation

II. Method

III. Result

From SDSS

BCGs, 2nd BCGs, & 3rd BCGs are redder

than Non-cluster galaxies.

They are different population.

The BCGs vs. NCGs

I. Motivation

II. Method

III. Result

From SDSS

CMR of ETGs

Cluster ETGs are optically red.

Non-cluster ETGs have a blue tail.

I. Motivation

II. Method

III. Result

From SDSS

Environmental Dependence

Gomez et al. 2003

I. Motivation

II. Method

III. Result

From SDSS

Environmental Dependence

I. Motivation

II. Method

III. Result

From SDSS

ρ vs. Rclustocentric

R/R200ρ

Red/B

lue

Red/B

lue

g -

r

g -

r

R/R200ρ

Galaxy position

in clusters

Local density effect

on galaxy colors>

Conclusion

New density measurement. minimize the incompleteness. A better tool for environment study.

New homogenous cluster catalogue. Color radial dependence Morphology-Density relation. Denser Environment Stronger MDR Denser Brighter BCGs Cluster Galaxies Redder than Non-cluster Galaxies. They are

different each other. BCGs and other cluster galaxies.

show the same Mr-density relation. Local galaxy density > Position in cluster

New density measurement. minimize the incompleteness. A better tool for environment study.

New homogenous cluster catalogue. Color radial dependence Morphology-Density relation. Denser Environment Stronger MDR Denser Brighter BCGs Cluster Galaxies Redder than Non-cluster Galaxies. They are

different each other. BCGs and other cluster galaxies.

show the same Mr-density relation. Local galaxy density > Position in cluster

All color logos

All color logos

All color logos

Measuring Density (Schawinski et al. 2006)

DEC

RA z

DEC

RA z

Line of Sight

1Mpc

I. Motivation

II. Method

III. Result

3 X σ v

A Demography of Cluster GalaxiesI. Motivation

II. Method

III. Result

From SDSS

Efficiency of the New Measurement

From SDSS

I. Motivation

II. Method

III. Result

BCGs are generally in centers.

BCG & MDG separation smaller, better.

Efficiency of the New Measurement

From SDSS

I. Motivation

II. Method

III. Result

CMR efficiency test with spectroscopic, early-type (fracdev_r > 0.95) member galaxies.

Completeness= Purity =

# of members in red-sequence100

# of all members

# of members in red-sequence100

# of all red-sequence

90% cover

15% contamination

Efficiency of the New Measurement

From SDSS

I. Motivation

II. Method

III. Result

Our new density parameter

Good tracer of cluster size and mass.

From SDSS

Spectrum analysis Line indices, SFR, etc. ― Clustocentric radius

SH’s SAM clusters with Khochfar’s semi-analytical model vs. Observed clusters Constrain SAM.

Future Study