Myung Gyoon Lee Department of Physics & Astronomy

Seoul National University, Korea

Next Generation CFHT workshop, Mar27-29, 2013, Hilo, Hawaii

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FOREVER ( FORmation & EVolution of clustERs

(of stars and galaxies) )!

Overview of current issues and limits of spectroscopic studies of extragalactic star clusters ◦ In Early Type Galaxies (ETGs)

◦ For Age, Metallicity, and Kinematics

What to do with ngCFHT

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One of the most shocking and intriguing findings: Color distribution of globular clusters in ETGs: Bimodal! (numerous references in Brodie & Strader 2006 ARAA)

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Globular Clusters in M49 (Geisler, Lee, & Kim 1996, AJ, Lee, Kim & Geisler 1998, AJ)

100 ETGs in Virgo (Cote+2004, Peng+2006,Jordan+2009)

Color distribution of globular clusters in bright ETGs: Bimodal!

5 Peng+2006 ACSVCS (Cote et al 2004)

What does color bimodality tell or what can we tell with it?

Two aspects for today 1) Halo Structure of ETGs & Dark Matter

2) How ETGs & GCs formed

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Massive ETGs have dual halos! A blue halo and a red halo.

Yin & Yang model?

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Lee+ (2012)

The blue halo (Metal-poor) ◦ Blue pops (GCs and faint stars)

◦ Metal-poor

◦ Rounder, Extended

◦ Non-rotating?

The red halo (Metal-rich) ◦ Red pops (GCs and bright stars)

◦ Main body of ETGs

◦ Metal-rich

◦ Flatter, Centrally concentrated

◦ Rotating?

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Globular Clusters in M49

(Lee, Kim & Geisler 1998 AJ)

Blue halo : Red halo

Metallicity and Age!

Kinematics!

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Last two decades: ◦ 4-10m telescopes with various spectrographs

◦ a history of agony and tantalizing clues!

Current status: ◦ Still difficult and challenging task for EGCs today

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Park, Lee, Arimoto et al. (2012, ApJ)

Re-analyzed line index data for GCs in 7 gEs in the literature ◦ M87, M49, M60, NGC 4636, NGC 5128, NC 1399, and NGC 1407

Derived [Fe/H] and age from a comparison of line indices with SSP model (Thomas+ 2003) for a combined sample of GCs in gEs (167 blue and 148 red GCs).

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(M87, M49:Cohen et al 1998, 2003, M60:Pierce 2006, NGC 4636: Park et al 2012,

NGC 5128: Woodley et al 2010, NGC 1399: Forbes et al 2001,

NGC 1407: Cenarro et al 2007, MW: Harris 2010)

Globular Clusters in

MWG (Puzia et al2002 )

NGC 5128 (Woodley et al 2010)

NGC 4636 (Park et al 2012 ),

Metallicity distribution is bimodal: ◦ Peaks at [Fe/H]=-1.25 and -0.42 : the MP halo & the MR halo

◦ (MW: [Fe/H] -1.52 and -0.52)

A larger fraction of high [Fe/H] than MW GCs

13 (Park, Lee et al. 2012, ApJ)

Young GCs:

◦ A broad range

◦ A larger fraction of high [Fe/H]

Old GCs:

◦ Both metal-poor & metal-rich!

◦ Low [Fe/H] GCs are major.

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A broad distribution: 1-15 Gyrs

Old GCs formed mostly early (>10 Gyr ago) !

Existence of young GCs with 1-10 Gyrs!!!

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Metal-poor GCs: The bulk formed at >10 Gyr ago.

◦ Some GCs with intermediate-age

Metal-rich GCs: ◦ Old GCs and young GCs

◦ A larger fraction of younger GCs.

Cosmic star formation history

(10 Gyr=z~2)

16 (Park, Lee et al. 2012, ApJ)

(current) A small N in a small region in a galaxy.

With ngCFHT, we can cover the entire GCS in each galaxy!

To study cluster formation history in a galaxy.

17 (Park, Lee et al. 2012, ApJ)

Lee et al (2010) Park et al (2012): Subaru + literature

Analysis of all velocity data in 7 gEs

Srader et al (2011): M87 MMT/Hectospec: 2hour(g<22, 1field), R=~5A (3700-9100A)

KEC/LRIS : 3hour(<g>=22.5, 4 mask), R=~4.0A (3300-5600A)

KEC/DEIMOS :3hour(I<23, 4mask)+0.6h(1mask), R=~1.5A (6500-8700A)

Pota et al (2013): (SLUGGS, 12 ETGs) KEC/DEIMOS: 1(M87)~2(N1407)hour : err(vel)~15km/s,

R=~1.5A

Park et al (2012, ApJ)

Obs(Park et al (2012) <-> Model(Bekki et al 2008)

Rotation/Velocity dispersion

Model(Bekki et al 2008)

Model(Bekki et al 2008)

Obs(Park et al (2012) <-> Model(Bekki et al 2005)

Rotation/velocity dispersion: Diversity!

A mixture (bibimbap) scenario for ETGs

(updated from Lee et al 2010b, ApJ).

** Every galaxy has a different formation history,

but massive galaxies have dual halos.

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Large aperture -> V<~23

Wide field of view: 1.6 square deg

R = 2000-6000, err(v)<~10

Kinematics, age, metallicity of star clusters

Targets: Virgo and (M31+M33, M81 Group, M106 Group, Leo I Group)

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Strader+(2011)

”M87 is not dynamically coupled to the Virgo cluster”

“W find no strong signatures of rotation, which was seen in the outer region previously (expected for a major merger).”

Why different from old results?

Strader et al (2011)

Cote et al (2001)

The most extensive case: M87 (Strader et al 2011)

What can ngCFHT do?

27 Lee, Park & Hwang (2010, Science): SDSS

Substructures around massive galaxies

Connecting structures

Diffuse large scale structure-IGCs (wandering GCs) !!!

Tips of icebergs!

See NGVS.

ngCFHT is an ideal tool for this!

The blue halos are much larger than the red halos!

IGCs are mostly blue GCs! (old & metal-poor?)

28 Lee, Park & Hwang (2010, Science): SDSS

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FOREVER ( FORmation & EVolution of clustERs

(of stars and galaxies) )!

With the power of ngCFHT,

a new era for extragalactic star clusters will be open.