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A Globular Cluster View of Massive Galaxy Formation

A Globular Cluster View of Massive Galaxy Formation . 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.

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A Globular Cluster View of Massive Galaxy Formation

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  1. A Globular Cluster View of Massive Galaxy Formation MyungGyoon Lee With Hong SooPark & 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

  2. Knowns for Massive Galaxies • Multi-wavelength surveys lead to remarkable advances in understanding offormation 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!

  3. Unknowns for Massive Galaxies • 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?

  4. How to Study Stellar Halos? • 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)

  5. Globular Clusters in a Massive E Galaxy in Virgo • 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). • GlobularClusters in M49 • (Geisler, Lee, & Kim 1996, AJ, Lee et al1998, AJ) • color

  6. Maps of Blue GCs and Red GCs: M59 • Data: homogeneous set of gz photometry of GCs in 100 Virgo ETGs in HST/ACSVCS (Cote+2004, Jordan+2009) – gray map • 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)

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

  8. Ellipticity (GC System) vsMv(galaxy) • Red GC systems show a strong correlation with Mv: fainter galaxies have more elongated red GC systems. • Blue GC systems show little correlation with Mv.

  9. Ellipticity (GC system) vs Rotation (galaxy) • 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. e(GCS-star) ellipticity (GCS) Rotational parameter (star)[ATLAS 3D]

  10. Structure of ETGs: a new view • Massive ETGs have dual halos! • A blue halo anda red halo. • Yin& Yang model? • Old view • New view

  11. Dual Halos in ETGs • GlobularClusters in M49 • (Lee,Kim & Geisler 1998 AJ) • 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? • Blue halo : Red halo

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

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

  14. What about Stellar Halos?

  15. Resolved Stars in Es • 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 andRed (metal-rich) RGBs! • Stars in M105(E1) • Blue: Red RGB • Lee & Jang (2014, in prep)

  16. Metallicity Distributions of Stars in M105 • Two components • Inner region(3-7 Reff): red RGB dominates • Outer region(10-13Reff): lueRGB gets stronger, while the peak metallicity of thbered RGB remains constant. • Inner region • Outer region • Blue: Red RGB • Showing two stellar halos: blueand red. • Metallicity, [M/H] • Lee & Jang (2014, in prep)

  17. Formation of Massive ETGs • 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. Summary • 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

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