Myung Gyoon Lee ( 李明均 )

Transcription

1 Myung Gyoon Lee ( 李明均 ) With Observational Cosmology Team Department of Physics & Astronomy Seoul National University, Korea Nov 1-4, 2011, The 3 rd Subaru Conference/The 1 st NAOJ Symposium, Galactic Archeology and Near-Field Cosmology, Shuzenji, Japan 1

2 In Through rugged ways to the stars by Harlow Shapley (1969). In 1907 Shapley entered Missouri University, majoring in Journalism. He opened the curriculum book for classes to take. The first course was a-r-c-h-a-e-o-l-g-y. I couldn t pronounce it. The second course was a-s-t-r-o-n-o-m-y. I could pronounce it and here I am. Here we are for a-r-c-h-a-e-o-l-g-y in astronomy, wandering through rugged ways to the galaxies. 2

3 Overview of recent findings on old globular clusters in the nearby universe (from the Local Group to the Virgo Cluster!), Providing only clues (not answers) on understanding early history of galaxies, Useful for big questions: Formation of dwarfs and GCs Formation of a halo (or dual halos), thin disk, thick disk, bar, and bulge in spirals Formation of ges 3

4 Old paradigm: GCs dsph, des, BCDs New paradigm: several kinds of GC-like objects GCs with multiple populations, Faint fuzzies, Extended SCs, Wandering GCs, UCD, & UFdSphs What are they? Some of them may be the first clusters? 4

5 Age, [Fe/H], [α/fe], kinematics & spatial distribution No luxury for details such as every element for EGCs, but can cover the entire GC system in a galaxy. Methods to derive age and [Fe/H]. CMDs of resolved stars: MSTO?? Only lower limits! Line index vs SSP models : common Spectral fitting, SED fitting: Color-Color diagrams vs SSP models: Color: minimum information 5

6 Age: All old for R GC <10kpc A large Spread : 7-14 Gyrs for 10< R GC <20kpc [Fe/H]: A large spread: Only low[fe/h] for R GC >60kpc Size (r h ): Larger for large R GC Only large ones for R GC >60kpc Data from Marin-Franch et al (2009), Dotter et al (2011), Carretta et al (2010) R GC [kpc] 6

7 Isolated dirr at d~500 kpc Hwang, Lee et al (2005, 2010) Discovered four new remote clusters using CFHT/Megacam. They are extended clusters, Old & metal-poor. SC4 SC3 SC2 SC1 7

8 A giant stellar halo in a dwarf galaxy (Lee et al 2005) SCs along the line? C1 is bound to NGC 6822 or is wandering in the Local Group? Poster035: Hwang etal 8

9 dirr at d~800 kpc Are starburst galaxies young? Old metal poor GCs in the halo say no. Subaru/MOIRCS, Suprime Cam Kim, M. et al (2009), Lim et al (2011) Poster 043: Lim & Lee HI: van de Hulst(2002) Young SCs: Tikhonov+(2009) GCs: Lim et al (2011) 9

10 A wide field survey of kilo globular clusters in M31 3d x 3 d imaging (KPNO 0.9m) with Washington filters & spectroscopy with WIYN/Hydra (Kim et al 2007, Lee et al 2008, 2010, 2011) Found ~110 new GCs! A master catalog of M31 GCs combining ours with previous ones: N(velocity)=633, N(old, Fe/H)=429, N(young, <3Gyr)=188 10

11 Lick index diagrams SSP model: Thomas et al 2004 Data:Puzia et al 2002, Lee et al 2011

12 Young GCs: ~220km/s strong rotation, thin disk Old metal-rich GCs: ~200km/s rotation + vel dispersion, bulge+thick disk! Old metal-poor GCs: ~100km/s rotation + vel dispersion, halo! Lee et al (2008, 2011) Young GCs Old Metal-rich GCs Old Metal-poor GCs Blue color map: number density of metal-poor GCs, Contours: number density of metal-rich GCs V[km/s]

13 Lee et al (2008, 2011) Bulge GCs are mainly metal-rich and old! Halo GCs are mostly metal-poor and old! Young Metal poor Medium Old Medium Metal rich

14 [Fe/H] gradient with a large dispersion both in GCs and stars! Remote clusters are metalpoor. [Fe/H](GC)<[Fe/H](stars) at the same Rp. GCs trace old history! M31GC:Lee et al (2011) red M31 dsphs: literature, green M31 stars: literature, blue MWGC: Harris 2010, black

15 M31 GCs show a broader age distribution than MW GCs M31 GCs are on average more metal-rich than MW GCs. merger in M31! MWG M31 15

16 d~9mpc Compact red GCs Faint fuzzies Maybe old, but [Fe/H] and ages are not yet known. Hwang & Lee et al (2008, 2010) NGC5195 NGC5194

17 M81: no particular feature. M82: Halo GCs are old & MP IGCs: IGC1 and 2 are ~40 kpc from M81 (intra-group?). They are old and metal-poor. M82: Lim et al (2011), Jang et al (2011) M81: Nantais & Huchra (2010) NGC 3077: Davidge (2004) 17

18 Two types of GCs in the Virgo cluster GCs in galaxies (galaxy GCs) GCs between galaxies (intracluster GCs=IGCs=wandering GCs) GCs in galaxies Metallicity and age Kinematics 18

19 Spectroscopic metallicity distribution: broad & bimodal! Metal-rich GCs are more dominant than metal-poor GCs in the inner region of a galaxy ( MW GCs). 19 [Fe/H] [Fe/H] (M87, M49:Cohen et al 1998, 2003, M60:Pierce 2006, NGC 4636: Park et al 2011, NGC 5128: Woodley et al 2010, NGC 1399: Forbes et al 2001, NGC 1407: Cenarro et al 2007, MW: Harris 2010)

20 Age distribution: broad ( MW GCs)! Metal-poor GCs are on average older than metal-rich GCs! (M60:Pierce 2006, NGC 4636: Park et al 2011 (Subaru), NGC 5128: Woodley et al 2010, NGC 1399: Forbes et al 2001, NGC 1407: Cenarro et al 2007, MW: Harris 2010) 20

21 ge GCs have a broader age distribution than MW GCs! Metal-poor GCs are on average a few Gyr older than metal-rich GCs! 21

22 M86, M84 (Virgo Center) NGC 4388 (M31?) 22

23 Substructures around massive galaxies Connecting structures Diffuse large scale structure-igcs (wandering GCs)!!! Lee, Park & Hwang (2010, Science): SDSS 23

24 Luminosity weighted galaxy number density map Correlation between GCs and Early type galaxies GC (E+S0+dE) (S+SB+Irr) 24

25 BGC: wider distribution than RGC IGCs are mostly blue GCs! (old & metal-poor?) 25

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27 *HST/ACS images: They are genuine GCs! -Williams et al (2007) 4 IGCs in Area 4 -Lee, Lim, et al (2011, in prep) several new IGCs 27

28 Dwarf galaxies! IGCs were formed originally in dwarf galaxies. IGCs were stripped off from dwarf galaxies due to massive galaxies. The first objects in the universe (Peebles & Dicke 1968)? 28

29 A mixture of rice, various vegetables with different colors, a few sauces including sesame oil and red pepper paste, and beef/egg (optional) Spiciness depends on the amount of red pepper paste Uniqueness: Diverse Inputs: many combinations of different elements (mechanisms: massive collapse, merger, accretion, heating etc) Uniform output: always intriguing, tasty, and healthy^_^ (Es, spirals, dwarfs, etc) - 29

30 1) Metal-poor GCs were formed mostly in dwarf galaxies, while metal-rich GCs were formed later with stars in massive galaxies or in dissipational merging galaxies. 2) Elliptical galaxies grow via dissipational or dissipationless merging of galaxies and via accretion of many dwarf galaxies. 3) The IGCs stripped off from dwarf galaxies are now being accreted locally to nearby massive galaxies, and globally to the galaxy center. 30

31 1) MWG is unique in the sense most GCs are old and it lacks of massive young GCs. 2) Most other galaxies have an extended cluster formation history in the early phase-merger!. 3) M31 halo is rotating! 4) [Fe/H] distributions in ges are bimodal. 5) Every galaxy has a different history! 6) Remote GCs (wandering GCs) may be old and metalpoor, but to be confirmed. 7) UCDs may be in the same boat as GCs. Need Giant Telescopes for better spectroscopy! 31