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Conference Introduction

Conference Introduction. Duncan Forbes Swinburne University. Conference Introduction. Thanks to Meghan, Frazer and Mike Preview the upcoming conference (ie I’ll give the least accurate talk) Personal and biased view (ie I’ll forget to mention your seminal paper on environment)

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Conference Introduction

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  1. Conference Introduction Duncan Forbes Swinburne University

  2. Conference Introduction Thanks to Meghan, Frazer and Mike Preview the upcoming conference (ie I’ll give the least accurate talk) Personal and biased view (ie I’ll forget to mention your seminal paper on environment) Lets have a clean and open discussion (no plutos)…

  3. Malaysia, March 2009 This conference aims to…disentangle the complex interplay between nature and nurture.

  4. SOC chair: Lourdes Verdes Montenegro

  5. Defining Environment Field, Group and Cluster • Projected local number density of nearby galaxies (volume density better) • Cluster-centric distance (which centric?)

  6. Defining Environment Halo, subhalo, satellite • Halo mass • 3D dark matter density

  7. Morphology-Density Relation With time, spirals are replaced by S0s - Dressler et al. 1997 Clusters Field Dressler 1980

  8. Morphology-SF-Density Relationfor Dwarf galaxies dI -> dE -> dSph Einasto et al. 1974 Mayer et al. 2006 Forbes et al. 2003

  9. What supresses star formation? Hopkins et al. 2004

  10. Environmental Madau plot Crain et al. 2009

  11. Supression at (group-like) densities • 2dFGRS (Lewis et al. 2002) and SDSS (Gomez et al. 2003) => pre-processing in Groups ? • The low density Field includes some quiescent galaxies (Gray et al. 2004) Gray et al. 2004

  12. What supresses star formation? Haines et al. 2007 Observation Lower density, less SF suppressed 100% star forming

  13. What supresses star formation? Haines et al. 2007 Observation Croton et al. 2006 Model

  14. Environmental Processes • Steady gas accretion • Ram pressure stripping (gas removal) • Strangulation (turnoff gas supply) • Interactions & Harassment (high ) • Mergers (low ) Review by Boselli & Gavazzi 2006

  15. High redshift gas accretion Stream-fed galaxies Dekel et al. 2009 Kacprzak et al. 2009

  16. Stripping in a Group Rasmussen et al. 2006

  17. Interactions and Mergers => Formation of dark-matter free Tidal Dwarf Galaxies ?

  18. Globular Cluster tidal stripping/accretion Bekki etal. 2003

  19. Environmental Processes • Ram pressure stripping (gas removal) • Strangulation (turnoff gas supply) • Steady gas accretion • Interactions & Harassment (high ) • Mergers (low ) Are their timescales and any feedback processes consistent with the observed Red sequence, green valley and blue cloud ?

  20. “The Dearth of Environment Dependence” Van den Bosch et al. 2008

  21. Van den Bosch etal. 2008

  22. Formation vs Assembly De Lucia 2007

  23. 50% NGC1400 MB = -20 E/S0 See poster by Foster et al. ~13 Gyrs old dissipative rapid burst Spolaor et al. 2008

  24. NGC 4649 Globular Clusters  Pierce et al. 2006

  25. Cluster-centric predictions Caution: global vs central values Caution: physical vs projected radii Caution: splashback De Lucia 2007

  26. Isolated Elliptical Galaxies A `control’ sample unaffected by the group/cluster environment • Reda, Forbes et al. (2004) • Early-type galaxy, V < 9,000 km/s, B < 14 No neighbours within: • 700 km/s • 0.67 Mpc in plane of the sky • 2 B mags (factor of 6 in mass) => 36 ellipticals

  27. Fundamental PlaneDeviant galaxies have young stellar populations and/or disturbed morphology Reda, Forbes & Hau 2005

  28. NGC 821 - the nearest isolated elliptical galaxy ?

  29. Radial Ages - NGC 821 Proctor,Forbes etal. 2005

  30. Galaxy Bimodality MV ~ -20, M~3x1010 Mo, Mhalo~6x1011Mo Luminosity function, Colour-magnitude, Star formation rates, bulge/disk ratio, X-ray emission, stellar age, AGN emission, M/L ratio Globular Cluster Specific Frequency Transition from hot accretion flows to cold accretion plus AGN/SN feedback (see Dekel, Keres, Croton etc)

  31. Relative GC numbers versus host galaxy stellar mass GC TN-parameter M* = galaxy stellar mass computed from 2MASS K-band mag Problem: Star formation histories vary Transition at M*~few x 1010 Msun (Forbes 2005)

  32. Galaxy Halo Mass Globular Cluster System Mass No clear environment trend Spitler & Forbes 2009

  33. Globular Clusters in Galaxy Clusters Where are the GCs in the Virgo galaxy cluster? 25% in M87 46% satellites 29%intracluster100% (Bekki et al. 2006) The GC mass of a cluster-sizedhalo should include these 3components.

  34. Galaxy Halo Mass Globular Cluster System Mass globular clusters are ~0.007% of a halo’s mass

  35. Potential method for determining Halo Masses… GC formation appears to be directly proportional to the host halo mass 0.007% of Halo Mass = (Globular Cluster System Mass)

  36. Conclusions • Massive isolated galaxies can be quiescent • Environment influences greater for dwarfs • Galaxy (and GC) properties are bimodal • Consider formation vs assembly times • Galaxies have (strong) mass trends • Some isolated galaxies show signs of a merger • Globular clusters provide an alternative probe of galaxy formation and assembly • And finally…

  37. …Not Nature vs Nurture but Nature AND Nurture Have a great conference…

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