1. Myung Gyoon Lee With Hong Soo Park & In Sung Jang Seoul National University, Korea Multiwavelength surveys: Formation and Evolution of Galaxies from the Early Universe to Today, May 11-16, 2014, Dubrovnik, Croatia 1

2.  Multi-wavelength surveys lead to remarkable advances in understanding of formation and evolution of massive galaxies. However, most methods are based on integrated stellar light! (Limits) 1) Observing only the inner regions of galaxies, seeing only a tip of an iceberg! 2) Difficult to distinguish multiple populations! 2

3.  Stellar Halos! Not dark, but very faint! 1) Do massive galaxies have a single halo or multiple halos? 2) What about their structure, metallicity, kinematics? 3) How different are halos in E galaxies from bulges in disk galaxies? 4) How did these halos form? 3

4.  Note that stellar halos occupy not only the outer region but also the inner region of a galaxy! (Two powerful probes) 1) Globular clusters (GCs), tracing halos. 2) Resolved stars, showing directly stellar halos!  Working better for early-type galaxies (ETGs) 4

5.  Color distribution of GCs is bimodal, showing that there are two types: blue (metal-poor) GCs and red (metal-rich) GCs.  Both may be older than 10 Gyr (corresponding to z>2). 5 Globular Clusters in M49 (Geisler, Lee, & Kim 1996, AJ, Lee et al 1998, AJ) color

6.  An example: M59 (E5) (Shapes of the GC systems) The red GC system is more elongated than the blue GC system.  Estimation of Ellipticity(e) of the GC systems in 23 bright E/S0 galaxies. (Park & Lee 2013, ApJL, 773,27) 6  Data: homogeneous set of gz photometry of GCs in 100 Virgo ETGs in HST/ACSVCS (Cote+2004, Jordan+2009) – gray map

7.  The ellipticity of the red GC systems show a tight correlation with galaxy stellar light, while the blue GC systems do much less.  7 Ellipticity (GC system) Ellipticity (galaxy stellar light)

8.  Red GC systems show a strong correlation with M v : fainter galaxies have more elongated red GC systems.  Blue GC systems show little correlation with M v. 8

9.  Ellipticity of the red GC systems shows a strong correlation with rotation of their host galaxy: the faster galaxies rotate, the more elongated their red GCSs are. In contrast, the blue GC systems do little. 9 Rotational parameter (star)[ATLAS 3D]  e(GCS-star) ellipticity (GCS)

10.  Massive ETGs have dual halos!  A blue halo and a red halo.  Yin & Yang model? 10 Old viewNew view

11.  Lee+ (2013)  The blue halo (metal-poor) ◦ Rounder, More extended ◦ Non-rotating?  The red halo (metal-rich) ◦ Main body of ETGs ◦ Strong correlation with stars ◦ Elongated, Compacter ◦ Rotating? 11 Globular Clusters in M49 (Lee, Kim & Geisler 1998 AJ) Blue halo : Red halo

12. 12 Lee, Park & Hwang (2010, Science): SDSS  Number density maps of GCs  Substructures around massive galaxies  Diffuse large scale structure- Intracluster GCs (wandering GCs) !!!

13.  The blue halos are much larger than the red halos!  (radial density profiles are flatter).  Intracluster GCs are mostly blue GCs! (old & metal- poor) 13 Lee, Park & Hwang (2010, Science): SDSS Blue GCs : Red GCs

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15.  M105, a standard E1 galaxy, at 10 Mpc in Leo. (Harris+ 2007, Lee & Jang 2014)  Resolved stars show two RGB pops:  Blue (metal-poor) RGB and Red (metal-rich) RGBs! 15 Lee & Jang (2014, in prep) Stars in M105(E1) Blue: Red RGB

16.  Two components  Inner region(3-7 R eff ): red RGB dominates  Outer region(10-13R eff ): lue RGB gets stronger, while the peak metallicity of thbe red RGB remains constant. 16 Metallicity, [M/H]  Showing two stellar halos: blue and red. Inner region Outer region Blue: Red RGB Lee & Jang (2014, in prep)

17. 17  Two mode formation! 1) Red halo mode ◦ In situ formation via dissipative collapse/merger ◦ Mostly metal-rich stars ◦ Starting from a or more massive progenitors with rotation 2) Blue halo mode ◦ Dissipationless merger/accretion ◦ Mostly metal-poor stars ◦ Mostly from dwarf galaxies  To be tested with simulations.

18. 18  Massive galaxies have dual halos!  We are seeing mostly the red halos embedded in much larger blue halos!  Massive galaxies formed in red and blue modes. New view